**3.1.5 Mucilage gums**

Mucilage gums are very viscous polysaccharides extracted from seeds or soft stems of plants; examples are psyllium (from *Plantago* species), yellow mustard (from *Sinapis alba*), and flax mucilage (from *Linum usitatissimum*). All of them are acidic polysaccharides with structures somewhat related to some of the exudate gums. Their utilization in certain food products is increasing due to their functional properties (viscosity, gelation, water binding) as well as to their bio-active role in prevention and/or treatment of certain diseases (Cui, 2005).

#### **3.1.5.1 Psyllium gum**

Psyllium gum can be extracted from seeds of the *Plantago* species. The gum is deposited in the seed coat; it is, therefore, advantageous to mechanically separate the outer layers from the rest of the seed before extraction. Psyllium gum can be extracted with hot water or mild alkaline solutions. The molecular structure of the gum is a highly branched acidic arabinoxylan. D-Glucuronic acid residues have also been found in this gum. Psyllium gum has a very high molecular weight (~1500 kDa) and does not completely dissolve in water. When dispersed in water, it swells and forms a mucilageous dispersion with gel-like properties. It is used primarily as a laxative and dietary fiber supplement in pharmaceutical and food industries.

#### **3.1.5.2 Yellow mustard mucilage**

Yellow mustard mucilage can be extracted from whole mustard seeds or from the bran. The mucilage contains a mixture of a neutral polysaccharide, composed mainly of glucose, and an acidic polysaccharide, containing galacturonic and glucuronic acids, galactose, and rhamnose residues. Detailed analysis of the neutral fraction of yellow mustard mucilage showed that it contains mainly (1→4)-linked -D-glucose residues. The *O*-2, *O*-3, and *O*-6 atoms of the (1→4)--D-glucan backbone may carry ether groups (ethyl or propyl). Depending on the polymer concentration, yellow mustard mucilage can form either viscous solution of weak gels. When it is mixed with locust bean gum, however, the gel rigidity can

(1→4)-linked α-D-galacturonopyranosyl backbone chain with randomly substituted xylosyl branches linked at the 3 position of the galacturonic acid residues. In spite of the availability of alternative materials, the continued use of the gum is the result of its unique functional

Gum karaya, also known as sterculia gum, is a branched acidic polysaccharide obtained from the exudates of the *Sterculia urens* tree of the Sterculiaceae family grown in India. The backbone chain is a rhamnogalacturonan consisting of α-(1→4)-linked D-galacturonic acid and α-(1→2)-linked-L-rhamnosyl residues. The side chain is made of (1→3)-linked β-Dglucuronic acid, or (1→2)-linked β-D-galactose on the galacturonic acid unit where one half

Gum ghatti is an amorphous translucent exudate of the *Anogeissus latifolia* tree of the Combretaceae family grown in India. The monosaccharide constituents of gum ghatti are Larabinose, D-galactose, D-mannose, D-xylose, and D-glucuronic acid in the ratio of

Mucilage gums are very viscous polysaccharides extracted from seeds or soft stems of plants; examples are psyllium (from *Plantago* species), yellow mustard (from *Sinapis alba*), and flax mucilage (from *Linum usitatissimum*). All of them are acidic polysaccharides with structures somewhat related to some of the exudate gums. Their utilization in certain food products is increasing due to their functional properties (viscosity, gelation, water binding) as well as to their bio-active role in prevention and/or treatment of certain diseases (Cui,

Psyllium gum can be extracted from seeds of the *Plantago* species. The gum is deposited in the seed coat; it is, therefore, advantageous to mechanically separate the outer layers from the rest of the seed before extraction. Psyllium gum can be extracted with hot water or mild alkaline solutions. The molecular structure of the gum is a highly branched acidic arabinoxylan. D-Glucuronic acid residues have also been found in this gum. Psyllium gum has a very high molecular weight (~1500 kDa) and does not completely dissolve in water. When dispersed in water, it swells and forms a mucilageous dispersion with gel-like properties. It is used primarily as a laxative and dietary fiber supplement in pharmaceutical

Yellow mustard mucilage can be extracted from whole mustard seeds or from the bran. The mucilage contains a mixture of a neutral polysaccharide, composed mainly of glucose, and an acidic polysaccharide, containing galacturonic and glucuronic acids, galactose, and rhamnose residues. Detailed analysis of the neutral fraction of yellow mustard mucilage showed that it contains mainly (1→4)-linked -D-glucose residues. The *O*-2, *O*-3, and *O*-6 atoms of the (1→4)--D-glucan backbone may carry ether groups (ethyl or propyl). Depending on the polymer concentration, yellow mustard mucilage can form either viscous solution of weak gels. When it is mixed with locust bean gum, however, the gel rigidity can

properties combined with a high degree of stability in a range of conditions.

of the rhamnose is substituted by (1→4) linked β-D-galactose.

**3.1.4.3 Gum karaya** 

**3.1.4.4 Gum ghatti** 

**3.1.5 Mucilage gums** 

**3.1.5.1 Psyllium gum** 

and food industries.

**3.1.5.2 Yellow mustard mucilage** 

2005).

10:6:2:1:2, with traces of 6-deoxyhexose.

be increased substantially. It has been shown that the neutral (1→4)--D-glucan fraction of yellow mustard mucilage synergistically interacts with galactomannans. Yellow mustard is used in processed meat formulations and salad dressing as a stabilizer and bulking agent.

#### **3.1.5.3 Flaxseed mucilage**

Flaxseed mucilage can be easily extracted from the seeds by soaking them in warm water. The mucilage constitutes the secondary wall material in the outermost layer of the seed. Upon hydration of the seeds, it expands, breaks the mucilage cells, and exudes on the surface of the seeds. Flaxseed mucilage contains 50 to 80% carbohydrates and 4 to 20% proteins and ash. Flaxseed mucilage contains a mixture of neutral polysaccharides, composed mainly of xylose, arabinose and galactose residues, and acidic polysaccharides, containing galactose, rhamnose, and galacturonic acid residues. The neutral fraction of flaxseed mucilage has a backbone of (1→4)-linked β-D-xylopyranosyl residues, to which arabinose and galactosecontaining side chains are linked at *O*-2 and/or *O*-3.

The acidic fraction of flaxseed mucilage has a rhamnogalacturonan backbone with (1→4) linked α-D-galacturonopyranosyl and (1→2)-linked α-L-rhamnopyranosyl residues. The ratio of neutral to acidic polysaccharides in flaxseed may vary substantially with their origin. Unfractionated flaxseed mucilage forms a viscous solution, but it is the neutral fraction that mainly contributes to the high viscosity and weak gel-like properties of this gum. Flaxseed mucilage has not yet been widely utilized mostly because of limited information about the structure and functional properties of this gum. Similar to other gums, flaxseed mucilage can be used as a thickener, stabilizer, and water-holding agent.

#### **3.1.6 Fructans**

Fructans are reserve polysaccharides in certain plants, either complementing or replacing starch. They can also be produced by certain species of bacteria. A main kind of fructans is inulin. Inulins are found in roots or tubers of the family of plants known as Compositae, including dandelions, chicory, lettuce, and Jerusalem artichoke. They can also be extracted from the Liliacae family, including lily bulbs, onion, tulips, and hyacinth. Inulin is a low molecular weight polysaccharide containing (2→1) linked β-D-Fru*p* residues.

#### **3.2 Seaweed hydrocolloids**

#### **3.2.1 Alginates**

Alginates constitute the primary structural polysaccharides of brown seaweeds (*Phaeophyceae*). The alginate molecules provide both flexibility and strength to the plants and these properties are adapted as necessary for growth conditions in the sea. The major species of seaweeds that produce alginates are *Macrocystis pyrifera,* grown primarily along the California coast of the USA*,* south- and north-western coasts of South America, and coasts of Australia and New Zealand. Other good sources of alginates are *Laminaria hyperborea*, *Laminaria digitata*, and *Laminaria japonica*, grown along the north Atlantic coast of the USA, Canada, France, and Norway. Alginates can also be synthesized by bacteria, *Pseudomonas aeruginosa* and *Azobacter vinelandii*. Alginates are unbranched copolymers of (1→4)-linked β-D-mannuronic acid (M) and α-L-guluronic acid (G) residues. If the uronic acid groups are in the acid form (–COOH), the polysaccharide, called alginic acid, is water insoluble. The sodium salts of alginic acid (–COONa), sodium alginates, are water soluble. The sequence of mannuronic and guluronic residues significantly affects the physicochemical properties of alginates. The ratio of β-D-mannuronic acid to α-L-guluronic

Hydrocolloids in Food Industry 29

3,6-anhydro-α-L-galactose residues, forms three-fold left-handed helices. These lefthanded threefold helices are stabilized by the presence of water molecules bound inside the double helical cavity (Labropoulos *et al.*, 2002) and exterior hydroxyl groups allow aggregation of up to 10 000 of these helices to form microdomains of spherical microgels

The agar helix is more compact due to the smaller amount of sulphate groups. Agar is a well known thermo-reversible gelling polysaccharide, which sets at 30 to 40°C. Being less sulphated than furcellaran, and κ- and ι-carrageenans, agar can form strong gels, which are, subject to pronounced syneresis, attributed to strong aggregation of double helices (not weakened by the sulphate groups). The ability to form reversible gels by simply cooling hot, aqueous solutions is the most important property of agar. Gelation depends exclusively on the formation of hydrogen bonds, where the random coils associate to form single helices

Xanthan gum is an extracellular polysaccharide produced by the bacterium *Xanthomonas campestris*. The primary structure of xanthan gum consists of a cellulosic backbone of *β*- (1→4) linked D-glucose units substituted on alternate glucose residues with a trisaccharide side chain. The trisaccharide side chain is composed of two mannose units separated by a glucuronic acid (Melton *et al.*, 1976). Approximately half the terminal mannose units are linked to a pyruvate group and the non-terminal residue usually carries an acetyl group. The carboxyl groups on the side chains render the gum molecules anionic. The pyruvic acid content of xanthan can vary substantially depending on the strain of *X. campestris*, resulting

Molecular modelling studies suggest that xanthan gum can assume a helical structure, with the side branches positioned almost parallel to the helix axis and stabilizing the structure. Xanthan gum forms very viscous solutions, and, at sufficiently high polymer concentration, it exhibits weak gel-like properties. It can form thermo-reversible gels when mixed with certain galactomannans (e.g., locust bean gum) or konjac glucomannan. Xanthan is widely used in foods because of its good solubility in either hot or cold solutions, high viscosity

Pullulan is an extracellular homopolysaccharide of glucose produced by many species of the fungus *Aureobasidium*, specifically *A. pullulans*. Pullulan contains (1→4) and (1→6)-linked α-D-glucopyranosyl residues. The ratio of (1→4) to (1→6) linkages is 2:1. Pullulan is generally built up of maltotriose units linked by (1→6) with much smaller amount of maltotetraose units. The presence of (1→6) glycosidic linkages increases flexibility of pullulan chains and resulted in their good solubility in water compared with other linear polysaccharides (e.g., amylose) (Cui, 2005). Pullulan easily dissolves in cold or hot water to form a stable, viscous solution that does not gel. A pullulan solution is stable over a wide range of pH and is also

Gellan gum is a fermentation polysaccharide produced by the microorganism *Sphingomonas elodea* (previously identified as *Pseudomonas elodea,* but later reclassified). Gellan gum is now

(Foord & Atkins, 1989) and double helices (Rees & Welsh, 1977).

even at very low concentrations, and excellent thermal stability.

(Boral *et al.,* 2008).

**3.3 Microbial hydrocolloids** 

in different viscosities of xanthan solutions.

relatively stable to heat (Imenson, 2010).

**3.3.1 Xanthan gum** 

**3.3.2 Pullulan** 

**3.3.3 Gellan gum** 

acid residues is usually 2:1, although it may vary with the algal species, the age of the plant as well as the type of tissue the alginates are extracted from (Cui, 2005). The main advantage of alginate as a gel former is its ability to form heat-stable gels which can set at room temperatures. In food applications, it is primarily gel formation with calcium ions which is of interest.

#### **3.2.2 Carrageenans**

Carrageenans are structural polysaccharides of marine red algae of the Rhodophyceae class. They are extracted mainly from *Chondrus crispus*, *Euchema cottoni*, *Euchema spinosum*, *Gigartina skottsbergi*, and *Iradaea laminarioides*. These red seaweeds grow mostly along the Atlantic coasts of North America, Europe, and the western Pacific coasts of Korea and Japan. Carrageenan extracted from seaweed is not assimilated by the human body, providing only fibre with no nutritional value, but it does provide unique functional characteristics that can be used to gel, thicken and stabilise food products and food systems. κ-carrageenans, ιcarrageenans, and furcellarans are linear polysaccharides whose backbone structure is based on a repeating disaccharide sequence of sulphate esters of (1→3) linked β-D-galactose and (1→4) linked 3,6-anhydro-α-D-galactose. They differ from each other in the number and position of sulphate groups. κ-carrageenans have one sulphate group per repeating disaccharide unit, positioned at C-4 of the β-D-galactopyranosyl residue, whereas ιcarrageenans have two sulphate groups, positioned at C-4 of the β-D-galactopyranosyl residue and C-2 of the 3,6-anhydro-α-D-galactopyranosyl residue. Furcellaran has a similar structure to κ-carrageenan, but it is less sulphated; only 40% of the β-D-galactopyranosyl residues carry the sulphate group at C-4. These two types of monosaccharide conformations, along with the presence of axial and equatorial glycosidic linkages, allow κ- and ιcarrageenans to assume a helical conformation. In solution, in the presence of some cations (K+, Rb+, Ca++), the double helices of furcellaran, κ- and ι-carrageenans can aggregate and form gel. κ-carrageenan and ι-carrageenan form thermally reversible gels, which range in texture from firm and brittle to soft and elastic.

The functional properties of carrageenan gels, such as rigidity, turbidity, and tendency to syneresis (separation of water from gel upon aging), generally decrease with the increasing degree of sulphation in these polymers. λ-carrageenans constitute another group of the red seaweed polysaccharides. The repeating disacharide unit in λ-carrageenans consists of β-Dgalactopyranosyl residue sulphated at C-2 (instead of C-4 as in ι- and κ-carrageenans) and 2, 6-di-*O*-sulfato-α-D-galactopyranosyl units (instead of 3, 6-anhydro-α-D-galactopyranosyl residue). λ-carrageenans are nongelling polysaccharides used as cold soluble thickeners in syrups, fruit drinks, pizza sauces, and salad dressings.

#### **3.2.3 Agar**

Agar constitutes another group of polysaccharides from red-purple algae of the *Rhodophyceae* class. The agar-yielding species of *Gracilaria* and *Gelidium* grow in the waters along the coast of Japan, New Zealand, South Africa, Southern California, Mexico, Chile, Morocco, and Portugal. Agar is a linear polysaccharide built up of the repeating disaccharide unit of (1→3)-linked β-D-galactose and (1→4)-linked 3,6-anhydro-α-Lgalactose residues. In contrast to carrageenans, agar is only lightly sulphated and may contain methyl groups. Methyl groups, when present, occur at C-6 of the (1→3)-linked β-D-galactose or C-2 of (1→4)-linked 3, 6-anhydro-α-L-galactose residues. Agar, containing

acid residues is usually 2:1, although it may vary with the algal species, the age of the plant as well as the type of tissue the alginates are extracted from (Cui, 2005). The main advantage of alginate as a gel former is its ability to form heat-stable gels which can set at room temperatures. In food applications, it is primarily gel formation with calcium ions which is

Carrageenans are structural polysaccharides of marine red algae of the Rhodophyceae class. They are extracted mainly from *Chondrus crispus*, *Euchema cottoni*, *Euchema spinosum*, *Gigartina skottsbergi*, and *Iradaea laminarioides*. These red seaweeds grow mostly along the Atlantic coasts of North America, Europe, and the western Pacific coasts of Korea and Japan. Carrageenan extracted from seaweed is not assimilated by the human body, providing only fibre with no nutritional value, but it does provide unique functional characteristics that can be used to gel, thicken and stabilise food products and food systems. κ-carrageenans, ιcarrageenans, and furcellarans are linear polysaccharides whose backbone structure is based on a repeating disaccharide sequence of sulphate esters of (1→3) linked β-D-galactose and (1→4) linked 3,6-anhydro-α-D-galactose. They differ from each other in the number and position of sulphate groups. κ-carrageenans have one sulphate group per repeating disaccharide unit, positioned at C-4 of the β-D-galactopyranosyl residue, whereas ιcarrageenans have two sulphate groups, positioned at C-4 of the β-D-galactopyranosyl residue and C-2 of the 3,6-anhydro-α-D-galactopyranosyl residue. Furcellaran has a similar structure to κ-carrageenan, but it is less sulphated; only 40% of the β-D-galactopyranosyl residues carry the sulphate group at C-4. These two types of monosaccharide conformations, along with the presence of axial and equatorial glycosidic linkages, allow κ- and ιcarrageenans to assume a helical conformation. In solution, in the presence of some cations (K+, Rb+, Ca++), the double helices of furcellaran, κ- and ι-carrageenans can aggregate and form gel. κ-carrageenan and ι-carrageenan form thermally reversible gels, which range in

The functional properties of carrageenan gels, such as rigidity, turbidity, and tendency to syneresis (separation of water from gel upon aging), generally decrease with the increasing degree of sulphation in these polymers. λ-carrageenans constitute another group of the red seaweed polysaccharides. The repeating disacharide unit in λ-carrageenans consists of β-Dgalactopyranosyl residue sulphated at C-2 (instead of C-4 as in ι- and κ-carrageenans) and 2, 6-di-*O*-sulfato-α-D-galactopyranosyl units (instead of 3, 6-anhydro-α-D-galactopyranosyl residue). λ-carrageenans are nongelling polysaccharides used as cold soluble thickeners in

Agar constitutes another group of polysaccharides from red-purple algae of the *Rhodophyceae* class. The agar-yielding species of *Gracilaria* and *Gelidium* grow in the waters along the coast of Japan, New Zealand, South Africa, Southern California, Mexico, Chile, Morocco, and Portugal. Agar is a linear polysaccharide built up of the repeating disaccharide unit of (1→3)-linked β-D-galactose and (1→4)-linked 3,6-anhydro-α-Lgalactose residues. In contrast to carrageenans, agar is only lightly sulphated and may contain methyl groups. Methyl groups, when present, occur at C-6 of the (1→3)-linked β-D-galactose or C-2 of (1→4)-linked 3, 6-anhydro-α-L-galactose residues. Agar, containing

of interest.

**3.2.3 Agar** 

**3.2.2 Carrageenans** 

texture from firm and brittle to soft and elastic.

syrups, fruit drinks, pizza sauces, and salad dressings.

3,6-anhydro-α-L-galactose residues, forms three-fold left-handed helices. These lefthanded threefold helices are stabilized by the presence of water molecules bound inside the double helical cavity (Labropoulos *et al.*, 2002) and exterior hydroxyl groups allow aggregation of up to 10 000 of these helices to form microdomains of spherical microgels (Boral *et al.,* 2008).

The agar helix is more compact due to the smaller amount of sulphate groups. Agar is a well known thermo-reversible gelling polysaccharide, which sets at 30 to 40°C. Being less sulphated than furcellaran, and κ- and ι-carrageenans, agar can form strong gels, which are, subject to pronounced syneresis, attributed to strong aggregation of double helices (not weakened by the sulphate groups). The ability to form reversible gels by simply cooling hot, aqueous solutions is the most important property of agar. Gelation depends exclusively on the formation of hydrogen bonds, where the random coils associate to form single helices (Foord & Atkins, 1989) and double helices (Rees & Welsh, 1977).

#### **3.3 Microbial hydrocolloids**

#### **3.3.1 Xanthan gum**

Xanthan gum is an extracellular polysaccharide produced by the bacterium *Xanthomonas campestris*. The primary structure of xanthan gum consists of a cellulosic backbone of *β*- (1→4) linked D-glucose units substituted on alternate glucose residues with a trisaccharide side chain. The trisaccharide side chain is composed of two mannose units separated by a glucuronic acid (Melton *et al.*, 1976). Approximately half the terminal mannose units are linked to a pyruvate group and the non-terminal residue usually carries an acetyl group. The carboxyl groups on the side chains render the gum molecules anionic. The pyruvic acid content of xanthan can vary substantially depending on the strain of *X. campestris*, resulting in different viscosities of xanthan solutions.

Molecular modelling studies suggest that xanthan gum can assume a helical structure, with the side branches positioned almost parallel to the helix axis and stabilizing the structure. Xanthan gum forms very viscous solutions, and, at sufficiently high polymer concentration, it exhibits weak gel-like properties. It can form thermo-reversible gels when mixed with certain galactomannans (e.g., locust bean gum) or konjac glucomannan. Xanthan is widely used in foods because of its good solubility in either hot or cold solutions, high viscosity even at very low concentrations, and excellent thermal stability.

#### **3.3.2 Pullulan**

Pullulan is an extracellular homopolysaccharide of glucose produced by many species of the fungus *Aureobasidium*, specifically *A. pullulans*. Pullulan contains (1→4) and (1→6)-linked α-D-glucopyranosyl residues. The ratio of (1→4) to (1→6) linkages is 2:1. Pullulan is generally built up of maltotriose units linked by (1→6) with much smaller amount of maltotetraose units. The presence of (1→6) glycosidic linkages increases flexibility of pullulan chains and resulted in their good solubility in water compared with other linear polysaccharides (e.g., amylose) (Cui, 2005). Pullulan easily dissolves in cold or hot water to form a stable, viscous solution that does not gel. A pullulan solution is stable over a wide range of pH and is also relatively stable to heat (Imenson, 2010).

#### **3.3.3 Gellan gum**

Gellan gum is a fermentation polysaccharide produced by the microorganism *Sphingomonas elodea* (previously identified as *Pseudomonas elodea,* but later reclassified). Gellan gum is now

Hydrocolloids in Food Industry 31

Thus, while sodium alginate is quite soluble, it does not have good stability at low pHs. By treating alginates with propylene oxide to form propylene glycol alginate ester, a modified

In a similar fashion, while normal guar gum is quite soluble in cold water, solubility can be greatly increased by forming the hydroxypropyl guar derivative, while simultaneously

Pure cellulose is completely in soluble in water as well as being poorly absorptive in its native form. By chemical treatment to form cellulose ether compounds, such as methyl cellulose and hydroxypropyl cellulose, water solubility can be imparted, thus making a

Liquid foods, as well as instant (soluble) coffee and other food powders, can be conveniently contained in a gelatin capsule (Maddox, 1971). The interior of the capsule contains a suitable instant food which dissolves or disperses promptly upon addition of water. The capsule is maintained in a dry form in a suitable enclosure, such as a hermetically sealed bottle, blisterpack packaging or the like, until use. Soft gelatin capsules are commonly used in food supplements. Gelatin is the basic capsule shell component and it is formulated with suitable ingredients to encapsulate a wide variety of materials. Gelatin's special properties are of particular interest in foods since it acts as a barrier and protects liquid capsule contents from the outside environment. On the one hand, gelatin acts as a physical barrier to bacteria, yeasts and molds. On the other, it provides a low-permeability membrane to gases. The gelatin shell is transparent, can be formed in a wide range of sizes and shapes and dissolves quickly in hot water, releasing its encapsulated liquid. The advantages of encapsulation are: portion control, easy use and storage, extended shelf-life, improved aesthetic appeal, the variety of sizes available, disposability and edibility, improved product aromatics versus time, and biodegradability. A wide range of filler materials can be encapsulated within these capsules, such as most vegetable oils, essential oils and fish oils, as well as suspensions of crystalline materials milled with oils. A few food applications are: real chicken broth capsules which retain and deliver flavor more effectively than the powder system, encapsulated lemon oil for meringue pie mix, mint essence capsules for the tinned goods

Liquid-core hydrocolloid capsules are liquids encapsulated in a spherical polymer membrane (Vergnaud, 1992). Production of these capsules included suspending cells in a sodium alginate solution, forming small spherical calcium alginate beads by cross-linking with calcium salt, and reacting with polylysine to create a polylysine alginate membrane around the bead. In the final stage, the bead's core, composed of calcium alginate gel, was solubilized, thus forming a liquid-core micro-capsule containing cells (Lim & Sun, 1980). With this procedure, cells could also be found in the membrane matrix, leading to the proposal of an approach to eliminate this possibility (Wong & Chang, 1991). In the latter approach, cells were entrapped in alginate-gel micro-spheres, which in turn were contained within larger beads, resulting in a greater distance between the cells and the surface of the larger alginate bead. Similar to (Lim and Sun's 1980) procedure, the surface of the larger

soluble alginate is formed that has exceptional stability under acidic conditions.

useful series of water soluble functional hydrocolloid polymers.

**4. Hydrocolloids in the production of special products** 

giving a greatly increased viscosity.

market (Moorhouse & Grundon, 1994).

**4.2 Liquid-core capsules** 

**4.1 Soft gelatin capsules** 

approved for food use in many countries including Australia, Canada, United States, Mexico, Chile, Japan, South Korea, and Philippines.

The molecular structure of gellan gum is a straight chain based on repeating glucose, rhamnose and glucuronic acid units. In its native or high-acyl form, two acyl substituents – acetate and glycerate – are present. Both substituents are located on the same glucose residue and, on average, there is one glycerate per repeat and one acetate per every two repeating unit (Kuo et al., 1986). In low-acyl gellan gum, the acyl groups are absent. Upon cooling of gellan solutions, the polysaccharide chains can assume double helices, which aggregate into weak gel structures (supported by van der Waals attractions). In the presence of appropriate cations (Na+ or Ca++), the double helices form cation-mediated aggregates, which leads to formation of strong gel networks. Acyl substituents present in native gellan interfere with the aggregation process, giving much weaker gels. In the branched variants of gellan, the side chains also interfere with the cation-induced aggregation, allowing only 'weak gel' formation.

#### **3.4 Animal hydrocolloids 3.4.1 Chitin and chitosan**

Chitin is a structural polysaccharide that replaces cellulose in many species of lower plants, e.g., fungi, yeast, green, brown, and red algae. It is also the main component of the exoskeleton of insects and shells of crustaceans (shrimp, lobster, and crab). The molecular structure of chitin is similar to that of cellulose, except that the hydroxyl groups at *O*-2 of the β-D-Glc*p* residues are substituted with *N*-acetylamino groups. Chitin forms a highly ordered, crystalline structure, stabilized by numerous intermolecular H-bonds. It is insoluble in water. However, when chitin is treated with strong alkali, the *N*-acetyl groups are removed and replaced by amino groups. This new water-soluble polysaccharide, called chitosan, contains, therefore, (1→4)-linked 2-amino-2-deoxy-β-D-glucopyranosyl residues. Chitosan is the only polysaccharide carrying a positive charge. It is not digested by humans and can be used as a dietary fiber.

#### **3.4.2 Gelatin**

Gelatin is a proteinaceous material obtained from animal connective tissue (collagen) using hydrolysis in acidic (type A) or basic (type B) solution followed by hot water extraction. Commercially, skins or bones of different animal species, such as beef, pork, fish and poultry, form the main raw material for gelatin production. The extracted gelatin is a group of molecules of different molecular weight (Imenson, 2010). The molecular weight profile depends on the process. The amino acid profile determines hydrogen bond formation and reactivity via side groups such as amine, imidazole, alcohol, amide and carboxylic acid. It hydrates readily in warm or hot water to give low-viscosity solutions that have good whipping and foaming properties. After cooling, the network of polypeptide chains associates slowly to form clear, elastic gels that are syneresis free.

#### **3.5 Chemically modified hydrocolloids**

Although all natural gums have inherently useful and uniquely functional properties, they also have inherent limitations and deficiencies which restrict their overall utilization. In many cases, these limitations can be removed by selective chemical modification and derivatization of the gum. In other cases, the overall functional properties can be improved by the chemical modification of the natural hydrocolloid.

approved for food use in many countries including Australia, Canada, United States,

The molecular structure of gellan gum is a straight chain based on repeating glucose, rhamnose and glucuronic acid units. In its native or high-acyl form, two acyl substituents – acetate and glycerate – are present. Both substituents are located on the same glucose residue and, on average, there is one glycerate per repeat and one acetate per every two repeating unit (Kuo et al., 1986). In low-acyl gellan gum, the acyl groups are absent. Upon cooling of gellan solutions, the polysaccharide chains can assume double helices, which aggregate into weak gel structures (supported by van der Waals attractions). In the presence of appropriate cations (Na+ or Ca++), the double helices form cation-mediated aggregates, which leads to formation of strong gel networks. Acyl substituents present in native gellan interfere with the aggregation process, giving much weaker gels. In the branched variants of gellan, the side chains also interfere with the cation-induced aggregation, allowing only

Chitin is a structural polysaccharide that replaces cellulose in many species of lower plants, e.g., fungi, yeast, green, brown, and red algae. It is also the main component of the exoskeleton of insects and shells of crustaceans (shrimp, lobster, and crab). The molecular structure of chitin is similar to that of cellulose, except that the hydroxyl groups at *O*-2 of the β-D-Glc*p* residues are substituted with *N*-acetylamino groups. Chitin forms a highly ordered, crystalline structure, stabilized by numerous intermolecular H-bonds. It is insoluble in water. However, when chitin is treated with strong alkali, the *N*-acetyl groups are removed and replaced by amino groups. This new water-soluble polysaccharide, called chitosan, contains, therefore, (1→4)-linked 2-amino-2-deoxy-β-D-glucopyranosyl residues. Chitosan is the only polysaccharide carrying a positive charge. It is not digested by humans

Gelatin is a proteinaceous material obtained from animal connective tissue (collagen) using hydrolysis in acidic (type A) or basic (type B) solution followed by hot water extraction. Commercially, skins or bones of different animal species, such as beef, pork, fish and poultry, form the main raw material for gelatin production. The extracted gelatin is a group of molecules of different molecular weight (Imenson, 2010). The molecular weight profile depends on the process. The amino acid profile determines hydrogen bond formation and reactivity via side groups such as amine, imidazole, alcohol, amide and carboxylic acid. It hydrates readily in warm or hot water to give low-viscosity solutions that have good whipping and foaming properties. After cooling, the network of polypeptide chains

Although all natural gums have inherently useful and uniquely functional properties, they also have inherent limitations and deficiencies which restrict their overall utilization. In many cases, these limitations can be removed by selective chemical modification and derivatization of the gum. In other cases, the overall functional properties can be improved

associates slowly to form clear, elastic gels that are syneresis free.

by the chemical modification of the natural hydrocolloid.

Mexico, Chile, Japan, South Korea, and Philippines.

'weak gel' formation.

**3.4 Animal hydrocolloids 3.4.1 Chitin and chitosan** 

and can be used as a dietary fiber.

**3.5 Chemically modified hydrocolloids** 

**3.4.2 Gelatin** 

Thus, while sodium alginate is quite soluble, it does not have good stability at low pHs. By treating alginates with propylene oxide to form propylene glycol alginate ester, a modified soluble alginate is formed that has exceptional stability under acidic conditions.

In a similar fashion, while normal guar gum is quite soluble in cold water, solubility can be greatly increased by forming the hydroxypropyl guar derivative, while simultaneously giving a greatly increased viscosity.

Pure cellulose is completely in soluble in water as well as being poorly absorptive in its native form. By chemical treatment to form cellulose ether compounds, such as methyl cellulose and hydroxypropyl cellulose, water solubility can be imparted, thus making a useful series of water soluble functional hydrocolloid polymers.

#### **4. Hydrocolloids in the production of special products**

#### **4.1 Soft gelatin capsules**

Liquid foods, as well as instant (soluble) coffee and other food powders, can be conveniently contained in a gelatin capsule (Maddox, 1971). The interior of the capsule contains a suitable instant food which dissolves or disperses promptly upon addition of water. The capsule is maintained in a dry form in a suitable enclosure, such as a hermetically sealed bottle, blisterpack packaging or the like, until use. Soft gelatin capsules are commonly used in food supplements. Gelatin is the basic capsule shell component and it is formulated with suitable ingredients to encapsulate a wide variety of materials. Gelatin's special properties are of particular interest in foods since it acts as a barrier and protects liquid capsule contents from the outside environment. On the one hand, gelatin acts as a physical barrier to bacteria, yeasts and molds. On the other, it provides a low-permeability membrane to gases. The gelatin shell is transparent, can be formed in a wide range of sizes and shapes and dissolves quickly in hot water, releasing its encapsulated liquid. The advantages of encapsulation are: portion control, easy use and storage, extended shelf-life, improved aesthetic appeal, the variety of sizes available, disposability and edibility, improved product aromatics versus time, and biodegradability. A wide range of filler materials can be encapsulated within these capsules, such as most vegetable oils, essential oils and fish oils, as well as suspensions of crystalline materials milled with oils. A few food applications are: real chicken broth capsules which retain and deliver flavor more effectively than the powder system, encapsulated lemon oil for meringue pie mix, mint essence capsules for the tinned goods market (Moorhouse & Grundon, 1994).

#### **4.2 Liquid-core capsules**

Liquid-core hydrocolloid capsules are liquids encapsulated in a spherical polymer membrane (Vergnaud, 1992). Production of these capsules included suspending cells in a sodium alginate solution, forming small spherical calcium alginate beads by cross-linking with calcium salt, and reacting with polylysine to create a polylysine alginate membrane around the bead. In the final stage, the bead's core, composed of calcium alginate gel, was solubilized, thus forming a liquid-core micro-capsule containing cells (Lim & Sun, 1980). With this procedure, cells could also be found in the membrane matrix, leading to the proposal of an approach to eliminate this possibility (Wong & Chang, 1991). In the latter approach, cells were entrapped in alginate-gel micro-spheres, which in turn were contained within larger beads, resulting in a greater distance between the cells and the surface of the larger alginate bead. Similar to (Lim and Sun's 1980) procedure, the surface of the larger

Hydrocolloids in Food Industry 33

LBG can be used successfully for ice pop stabilization. Karaya, as well as carrageenan, can be used as a binder and emulsifying agent in quantities of less than ~1%. The binders are used to absorb the water resulting from the ice during chopping. LBG is used in the food industry for its ability to bind and immobilize large amounts of water. This property helps inhibit ice crystal formation in frozen products, produce viscosity, modify texture and stabilize product consistency in the face of temperature changes (Glicksman, 1969). Sodium CMC in its highest purified form is used in many food applications. In frozen desserts (such as ice cream), cellulose gum inhibits the formation of ice crystals (Davidson, 1980). Gum arabic, because of its water-absorbing properties, gum inclusion inhibits the formation and growth of ice crystals. Other stabilizers, such as carrageenan and LBG, can be used for the same purposes (Glicksman, 1969). Guar gum is used in the food industry for its ability to bond and immobilize large amounts of water. This property contributes to inhibition of ice crystal formation, product texture, stabilization of product consistency to changes in

Freezing often causes undesirable changes in foods, and hydrocolloids are used to improve their quality. To produce a high-quality ice cream, a blend of guar gum or CMC with a smaller amount of carrageenan may be used. If xanthan and guar gum are used instead, viscosity is lower and faster processing is obtained. Karaya gum has been used in the past as a stabilizer for frozen desserts, but has been replaced almost completely by other gums. Carrageenan, guar gum and CMC have also been used as stabilizers in other frozen products. In foods containing starch as the main ingredient, there is a tendency for water to exude from the gel. Thus starch-based products curdle and undergo syneresis (loss of water) after freezing and thawing. Modified starches have been developed to deal with the

Frozen doughs are widely used in industrial bakeries to make baking more profitable. However, loaf volumes are usually smaller and quality poorer for breads baked from frozen doughs, especially in those with low fat content (Williams & Philips, 1998). Addition of hydrocolloids such as CMC, alginate, and different blends in quantities of up to 1.5% yielded higher total dough water content without changing baking properties. There were

Candies are popular products among children and adults and their versatility is visually alluring as well as pleasing to the consumer. The confectionery industry uses gum arabic to a great extent, for crystallization prevention, as an emulsification agent of fat and as a glaze in candies, chewing gum. Gum arabic serves to coat the center of sugar-coated tablets. It is the main ingredient in gumdrops (regular and dietetic) and other chewy-type gums, where pectin or modified starches can also play a major role (Davidson, 1980). The incorporation of sorbitol, mannitol and gum arabic can produce dietetic candies. The higher the gum arabic

Using fish, meat, fruit or vegetables as main ingredients within a matrix, which is usually produced from a gum, can create fabricated foods. Gums were incorporated into meat products to achieve better control of their texture, improve sliceability and increase yield. In some meat products, hydrocolloids are responsible for the undesirable broad dark striations (called tiger stripping), running parallel to the meat fibers (Williams & Philips, 1998). The swelling ability of the type of carrageenan used influences its activity within the product.

no obvious differences between analyzed samples or added hydrocolloid levels.

temperature, and viscosity (Davidson, 1980).

problem (Nussinovitch, 1997).

content, the softer and chewier the candy.

**4.6 Candies** 

**4.7 Fabricated foods** 

micro-sphere was reacted with poly-L-lysine and then with alginate to form a coating membrane. The contents of the micro-capsule were then liquefied with sodium citrate to remove the calcium from the array. The cells in the smaller entrapped gel micro-sphere were released and allowed to float freely in the liquid core of the resultant beads (Wong & Chang, 1991).

The contents of the capsule were either distilled water or sucrose solutions (2.5 and 30%, w/w), although other viscous liquids can be used. Beads with 0, 2 and 5% sucrose were produced by diffusion of sucrose out of liquid-core capsules containing 30% sucrose. The spherical shape of the capsule was retained after diffusion. Capsules with a higher hydrocolloid concentration within their membrane displayed more stress at failure (strength) and less brittleness than those with lesser solid membrane content. Following diffusion, capsules with 2 and 5% sucrose were weak compared to those with 30% sucrose; however, no membrane rupture was observed after incubation.

#### **4.3 Jelly-like foods**

Natural gums are used in the confectionary industry. At one time, guar was used for production of jellies (candies) and marshmallows, and gum arabic was used gum drops. The gum within the formulation served to form *jelly*, but an additional function was to prevent sugar crystallization and to emulsify fat, keeping it evenly distributed within the product (Furia, 1980). The gum powder swells and gels when added to water and heated. Its gels are thermally irreversible and unaffected by further addition of water and can be produced over a pH range of 2.0-9.5 in the presence of many food additives. The gels may be used to make novel food products consisting of a jelly-like skin with a liquid core, and canned jellies. The concentration of the polysaccharide in water must be greater than 1.5% for gel stability and less than 0.6% for taste acceptability. The gels are freeze-thaw stable and may be used to make an ice confection contained in an elastic gel skin (Anon, 1977).

#### **4.4 Fruit products**

A combination of compression and shearing forces is used to extract juice from fruits or vegetables. For pulp production, and in the case of grapes, tomatoes or other soft fruits, are heated, if necessary, to soften their tissues and pulp is forced through the perforations of the pulping equipment's screen, the size of which determines the consistency of the resultant product (Fellows, 2000). Unique uses of such fruit products (i.e. juice, pulp or puree) for production of soft viscous, fruit-based, membrane-coated items by a membrane were described decades ago. For example fruit juice, pulp or puree containing soluble Ca salt is extruded to form drops which are coated with a thin skin of alginate or pectate sol. The coated drops are exposed to an aqueous setting bath containing a soluble Ca salt (Sneath, 1975). Drops of aqueous fruit material are coated with an aqueous alginate or pectate solution and applied in a solution containing Ca or Al ions to gel the surface.

#### **4.5 Frozen product**

Frozen desserts are mixtures of ice crystals in flavored liquid syrup. The most common frozen dessert is ice cream. During the last 50 years, a huge change in the texture of icecream products has occurred.

Gum karaya can be used as a stabilizer in ice cream, ice milk, mellorine and related products. In ice pops and sherbets, formation of large ice crystals and syneresis can be prevented by including 0.2-0.4% gum karaya. Combinations of 0.15% gum karaya and 0.15%

micro-sphere was reacted with poly-L-lysine and then with alginate to form a coating membrane. The contents of the micro-capsule were then liquefied with sodium citrate to remove the calcium from the array. The cells in the smaller entrapped gel micro-sphere were released and allowed to float freely in the liquid core of the resultant beads (Wong & Chang,

The contents of the capsule were either distilled water or sucrose solutions (2.5 and 30%, w/w), although other viscous liquids can be used. Beads with 0, 2 and 5% sucrose were produced by diffusion of sucrose out of liquid-core capsules containing 30% sucrose. The spherical shape of the capsule was retained after diffusion. Capsules with a higher hydrocolloid concentration within their membrane displayed more stress at failure (strength) and less brittleness than those with lesser solid membrane content. Following diffusion, capsules with 2 and 5% sucrose were weak compared to those with 30% sucrose;

Natural gums are used in the confectionary industry. At one time, guar was used for production of jellies (candies) and marshmallows, and gum arabic was used gum drops. The gum within the formulation served to form *jelly*, but an additional function was to prevent sugar crystallization and to emulsify fat, keeping it evenly distributed within the product (Furia, 1980). The gum powder swells and gels when added to water and heated. Its gels are thermally irreversible and unaffected by further addition of water and can be produced over a pH range of 2.0-9.5 in the presence of many food additives. The gels may be used to make novel food products consisting of a jelly-like skin with a liquid core, and canned jellies. The concentration of the polysaccharide in water must be greater than 1.5% for gel stability and less than 0.6% for taste acceptability. The gels are freeze-thaw stable and may be used to

A combination of compression and shearing forces is used to extract juice from fruits or vegetables. For pulp production, and in the case of grapes, tomatoes or other soft fruits, are heated, if necessary, to soften their tissues and pulp is forced through the perforations of the pulping equipment's screen, the size of which determines the consistency of the resultant product (Fellows, 2000). Unique uses of such fruit products (i.e. juice, pulp or puree) for production of soft viscous, fruit-based, membrane-coated items by a membrane were described decades ago. For example fruit juice, pulp or puree containing soluble Ca salt is extruded to form drops which are coated with a thin skin of alginate or pectate sol. The coated drops are exposed to an aqueous setting bath containing a soluble Ca salt (Sneath, 1975). Drops of aqueous fruit material are coated with an aqueous alginate or pectate

Frozen desserts are mixtures of ice crystals in flavored liquid syrup. The most common frozen dessert is ice cream. During the last 50 years, a huge change in the texture of ice-

Gum karaya can be used as a stabilizer in ice cream, ice milk, mellorine and related products. In ice pops and sherbets, formation of large ice crystals and syneresis can be prevented by including 0.2-0.4% gum karaya. Combinations of 0.15% gum karaya and 0.15%

however, no membrane rupture was observed after incubation.

make an ice confection contained in an elastic gel skin (Anon, 1977).

solution and applied in a solution containing Ca or Al ions to gel the surface.

1991).

**4.3 Jelly-like foods** 

**4.4 Fruit products** 

**4.5 Frozen product** 

cream products has occurred.

LBG can be used successfully for ice pop stabilization. Karaya, as well as carrageenan, can be used as a binder and emulsifying agent in quantities of less than ~1%. The binders are used to absorb the water resulting from the ice during chopping. LBG is used in the food industry for its ability to bind and immobilize large amounts of water. This property helps inhibit ice crystal formation in frozen products, produce viscosity, modify texture and stabilize product consistency in the face of temperature changes (Glicksman, 1969). Sodium CMC in its highest purified form is used in many food applications. In frozen desserts (such as ice cream), cellulose gum inhibits the formation of ice crystals (Davidson, 1980). Gum arabic, because of its water-absorbing properties, gum inclusion inhibits the formation and growth of ice crystals. Other stabilizers, such as carrageenan and LBG, can be used for the same purposes (Glicksman, 1969). Guar gum is used in the food industry for its ability to bond and immobilize large amounts of water. This property contributes to inhibition of ice crystal formation, product texture, stabilization of product consistency to changes in temperature, and viscosity (Davidson, 1980).

Freezing often causes undesirable changes in foods, and hydrocolloids are used to improve their quality. To produce a high-quality ice cream, a blend of guar gum or CMC with a smaller amount of carrageenan may be used. If xanthan and guar gum are used instead, viscosity is lower and faster processing is obtained. Karaya gum has been used in the past as a stabilizer for frozen desserts, but has been replaced almost completely by other gums. Carrageenan, guar gum and CMC have also been used as stabilizers in other frozen products. In foods containing starch as the main ingredient, there is a tendency for water to exude from the gel. Thus starch-based products curdle and undergo syneresis (loss of water) after freezing and thawing. Modified starches have been developed to deal with the problem (Nussinovitch, 1997).

Frozen doughs are widely used in industrial bakeries to make baking more profitable. However, loaf volumes are usually smaller and quality poorer for breads baked from frozen doughs, especially in those with low fat content (Williams & Philips, 1998). Addition of hydrocolloids such as CMC, alginate, and different blends in quantities of up to 1.5% yielded higher total dough water content without changing baking properties. There were no obvious differences between analyzed samples or added hydrocolloid levels.

#### **4.6 Candies**

Candies are popular products among children and adults and their versatility is visually alluring as well as pleasing to the consumer. The confectionery industry uses gum arabic to a great extent, for crystallization prevention, as an emulsification agent of fat and as a glaze in candies, chewing gum. Gum arabic serves to coat the center of sugar-coated tablets. It is the main ingredient in gumdrops (regular and dietetic) and other chewy-type gums, where pectin or modified starches can also play a major role (Davidson, 1980). The incorporation of sorbitol, mannitol and gum arabic can produce dietetic candies. The higher the gum arabic content, the softer and chewier the candy.

#### **4.7 Fabricated foods**

Using fish, meat, fruit or vegetables as main ingredients within a matrix, which is usually produced from a gum, can create fabricated foods. Gums were incorporated into meat products to achieve better control of their texture, improve sliceability and increase yield. In some meat products, hydrocolloids are responsible for the undesirable broad dark striations (called tiger stripping), running parallel to the meat fibers (Williams & Philips, 1998). The swelling ability of the type of carrageenan used influences its activity within the product.

Hydrocolloids in Food Industry 35

a 6-week washout period, a control cereal. Consumption of psyllium gave a 7% reduction in

Many human studies on guar effect on lipid metabolism have been conducted. The dose of guar gum was 10 g and it was taken three times a day for 6 weeks. In comparison with a placebo, the guar gum decreased the blood cholesterol and triglyceride levels and blood pressure significantly (Landin et al., 1992). The effect of guar gum on LDL metabolism seemed to be related to an increased LDL a polipoprotein B fractional catabolism. Modified guar gum has also been studied, and in one study partially depolymerized guar gum decreased the total cholesterol levels by 10%, which is a reduction similar to that found earlier for high molecular weight guar gum (Blake et al., 1997). The effects of solid or liquid guar gum and preparations with high or medium viscosity on lipid metabolism were followed in hypercholesterolemic subjects (Superko et al., 1988). Both solid and liquid guar gum preparations lowered the total and LDL cholesterol, but the high-viscosity preparation

gave a larger reduction in blood lipid levels than the medium-viscosity preparation.

with increasing degree of methylation more bile acids were excreted with the feces.

Pectin can be included in the diet as a supplement, but also as fruits, which often contain much pectin. In a study, subjects with hypertension were given guava fruits before meals during 12 weeks, and the effect on the blood lipids and blood pressure was followed (Singh et al., 1992). In comparison with a group that was not given guava, the total cholesterol, HDL cholesterol, triglycerides, and blood pressure decreased significantly. Several studies have also been done with different kinds of pectins. Dongowski & Lorentz (2004) gave diets containing pectin with different degrees of methylation (34.5, 70.8, and 92.6%) to rats for 3 weeks. The concentration of bile acids in the plasma decreased when pectin was given, and

It has been reported that dietary soluble fiber such as β-glucan, psyllium, and guar gum decreases glucose and insulin responses to carbohydrates if taken in sufficient amounts. A study comparing the effects over 6 months of barley bread, high in β-glucan, to white bread found that barley bread improved glycemic control compared with white wheat bread in 11 men with type 2 diabetes.97 Insulin responses were increased, which hypothetically could reflect recovered β-cell function. In men with diabetes and hypercholesterolemia participating in a crossover trial, 8 weeks of psyllium (15 g/day) decreased hemoglobin A1c 6.1% (absolute change, 0.8%), with similar 6% decreases in fasting postprandial glucose (Anderson et al., 1999). Improved fasting and postprandial glycemic control was found in 11 type 2 diabetic patients taking 21 g/day of guar gum or placebo in a randomized doubleblinded crossover trial (Aro et al., 1981). Small improvements in overall glycemic control and sizable improvements in postprandial glycemia after 4 weeks of treatment in a randomized controlled crossover trial were reported by Fuessl et al. (1987) Guar gum decreased fasting blood glucose from 11.4 to 9.5 mmol/l in 19 obese patients with type 2 diabetes who were enrolled in a randomized double-blind crossover trial (Lalor et al., 1990). Guar gum (15 g/day) has also improved long-term glycemic control and postprandial glucose tolerance in 15 type 2 diabetic patients treated with guar gum over an 8-week period (Groop et al., 1993). Viscosity is an important determinant of soluble hydrocolloid in

The laxative activity of bulk forming substances has been known since the time of Hippocrates. Hydrocolloid fractions of psyllium and ispaghula are common bulk forming

LDL cholesterol compared with the control cereal.

**5.2 Hydrocolloids and type 2 diabetes** 

retarding glycemic responses (Wood et al., 2000).

**5.3 Hydrocolloids as laxative and antidiarrhea** 

Semi-refined carrageenan (less swelling) improved performance in injected poultry by reducing the incidence of tiger stripping without reducing purge controls (Williams & Philips, 1998).

Fabricated fruit is easily manufactured with alginates. A gel is readily formed when a soluble calcium salt is added to a sodium alginate solution. This gel is stable over a wide range of temperatures, has excellent syneresis control, and is irreversible to heat. Possible uses for this fabrication concept include imitation cocktail cherries; imitation glazed fruit pieces for cakes, breads, cookies, ice cream and candy products; icing; and gelled products containing pureed fruit. Other hydrocolloids - carrageenan, gelatin (and recently gellan), and combinations of gums such as carrageenan and locust bean gum (LBG) - have been used to fabricate food products. Examples include reconstituted pimento strips (based on alginate and gum arabic), the aforementioned imitation caviar, and restructured fish and shellfish (Nussinovitch, 1997).

Use of sodium carboxymethyl cellulose (CMC) in food applications is on the rise, especially in developed countries where the popularity and convenience of fabricated foods has grown rapidly since the early 1950s. Hydroxypropylcellulose can also be used in fabricated foods to a large extent. Its useful properties are its ability to form solvent-soluble films and its surface-active stabilization (Davidson, 1980).

#### **5. Health benefits of hydrocolloids**

#### **5.1 Hydrocolloid and the risk of cardiovascular disease (CVD)**

Dietary fiber was briefly mentioned in the WHO report to reduce total and LDL cholesterol, and probably also to decrease the risk for cardiovascular diseases. Several studies have dealt with the association between dietary fiber intake and risk for cardiovascular disease. The main interest has been focused on effects of soluble fibers, such as different hydrocolloids, and thus on foods rich in soluble fibers. Both mixture of hydrocolloids and only one hydrocolloid were investigated. In one study, subjects with increased plasma cholesterol values were given a daily supplement of 15 g of psyllium, pectin, guar gum, and locust bean gum during 6 months (Jensen et al., 1997). The fibers were mixed in water and consumed with each of three major daily meals. In comparison with the control group given acacia gum, the total and LDL cholesterol values were significantly lower in the test group. After 8 weeks, the reductions in comparison with baseline were 6.4 and 10.5%, respectively, and about the same reductions were found at weeks 16 and 24. In another study, a combination of soluble fibers from psyllium, oats, and barley was given to men with hypercholesterolemia (Roberts et al., 1994). They consumed the fibers as a breakfast cereal (50 g containing 12 g of soluble fiber) for 6 weeks. In comparison with a control group given a breakfast cereal based on wheat, the total cholesterol and LDL cholesterol levels fell significantly in the test group, with 3.2 and 4.4%, respectively.

Psyllium has been extensively investigated in relation to its effects on CVD. As in the study of Anderson et al. (2000), the fiber preparations were mixed in water and taken before regular meals three times per day. A dose–response study was made by Davidson et al. (1998) using psyllium seed husk given in daily doses of 0, 3.4, 6.8, or 10.2 g for 24 weeks. The fibers were included in different foods like ready-to-eat cereals, bread, pasta, and snack bars. A change in LDL cholesterol (–5.3% in comparison to control) after 24 weeks consumption was only shown for the group that took the highest dose of psyllium husk-10.2 g/day. The reduction in LDL cholesterol was more pronounced in the beginning of the intervention (week 4) for all groups. Davidson et al. (1998) also investigated the lipid-lowering effect of psyllium in hypercholesterolemic children (6 to 18 years). They were given psyllium for 6 weeks and, after

Semi-refined carrageenan (less swelling) improved performance in injected poultry by reducing the incidence of tiger stripping without reducing purge controls (Williams &

Fabricated fruit is easily manufactured with alginates. A gel is readily formed when a soluble calcium salt is added to a sodium alginate solution. This gel is stable over a wide range of temperatures, has excellent syneresis control, and is irreversible to heat. Possible uses for this fabrication concept include imitation cocktail cherries; imitation glazed fruit pieces for cakes, breads, cookies, ice cream and candy products; icing; and gelled products containing pureed fruit. Other hydrocolloids - carrageenan, gelatin (and recently gellan), and combinations of gums such as carrageenan and locust bean gum (LBG) - have been used to fabricate food products. Examples include reconstituted pimento strips (based on alginate and gum arabic), the aforementioned imitation caviar, and restructured fish and shellfish (Nussinovitch, 1997). Use of sodium carboxymethyl cellulose (CMC) in food applications is on the rise, especially in developed countries where the popularity and convenience of fabricated foods has grown rapidly since the early 1950s. Hydroxypropylcellulose can also be used in fabricated foods to a large extent. Its useful properties are its ability to form solvent-soluble films and its

Dietary fiber was briefly mentioned in the WHO report to reduce total and LDL cholesterol, and probably also to decrease the risk for cardiovascular diseases. Several studies have dealt with the association between dietary fiber intake and risk for cardiovascular disease. The main interest has been focused on effects of soluble fibers, such as different hydrocolloids, and thus on foods rich in soluble fibers. Both mixture of hydrocolloids and only one hydrocolloid were investigated. In one study, subjects with increased plasma cholesterol values were given a daily supplement of 15 g of psyllium, pectin, guar gum, and locust bean gum during 6 months (Jensen et al., 1997). The fibers were mixed in water and consumed with each of three major daily meals. In comparison with the control group given acacia gum, the total and LDL cholesterol values were significantly lower in the test group. After 8 weeks, the reductions in comparison with baseline were 6.4 and 10.5%, respectively, and about the same reductions were found at weeks 16 and 24. In another study, a combination of soluble fibers from psyllium, oats, and barley was given to men with hypercholesterolemia (Roberts et al., 1994). They consumed the fibers as a breakfast cereal (50 g containing 12 g of soluble fiber) for 6 weeks. In comparison with a control group given a breakfast cereal based on wheat, the total cholesterol and LDL cholesterol levels fell

Psyllium has been extensively investigated in relation to its effects on CVD. As in the study of Anderson et al. (2000), the fiber preparations were mixed in water and taken before regular meals three times per day. A dose–response study was made by Davidson et al. (1998) using psyllium seed husk given in daily doses of 0, 3.4, 6.8, or 10.2 g for 24 weeks. The fibers were included in different foods like ready-to-eat cereals, bread, pasta, and snack bars. A change in LDL cholesterol (–5.3% in comparison to control) after 24 weeks consumption was only shown for the group that took the highest dose of psyllium husk-10.2 g/day. The reduction in LDL cholesterol was more pronounced in the beginning of the intervention (week 4) for all groups. Davidson et al. (1998) also investigated the lipid-lowering effect of psyllium in hypercholesterolemic children (6 to 18 years). They were given psyllium for 6 weeks and, after

Philips, 1998).

surface-active stabilization (Davidson, 1980).

**5.1 Hydrocolloid and the risk of cardiovascular disease (CVD)** 

significantly in the test group, with 3.2 and 4.4%, respectively.

**5. Health benefits of hydrocolloids** 

a 6-week washout period, a control cereal. Consumption of psyllium gave a 7% reduction in LDL cholesterol compared with the control cereal.

Many human studies on guar effect on lipid metabolism have been conducted. The dose of guar gum was 10 g and it was taken three times a day for 6 weeks. In comparison with a placebo, the guar gum decreased the blood cholesterol and triglyceride levels and blood pressure significantly (Landin et al., 1992). The effect of guar gum on LDL metabolism seemed to be related to an increased LDL a polipoprotein B fractional catabolism. Modified guar gum has also been studied, and in one study partially depolymerized guar gum decreased the total cholesterol levels by 10%, which is a reduction similar to that found earlier for high molecular weight guar gum (Blake et al., 1997). The effects of solid or liquid guar gum and preparations with high or medium viscosity on lipid metabolism were followed in hypercholesterolemic subjects (Superko et al., 1988). Both solid and liquid guar gum preparations lowered the total and LDL cholesterol, but the high-viscosity preparation gave a larger reduction in blood lipid levels than the medium-viscosity preparation.

Pectin can be included in the diet as a supplement, but also as fruits, which often contain much pectin. In a study, subjects with hypertension were given guava fruits before meals during 12 weeks, and the effect on the blood lipids and blood pressure was followed (Singh et al., 1992). In comparison with a group that was not given guava, the total cholesterol, HDL cholesterol, triglycerides, and blood pressure decreased significantly. Several studies have also been done with different kinds of pectins. Dongowski & Lorentz (2004) gave diets containing pectin with different degrees of methylation (34.5, 70.8, and 92.6%) to rats for 3 weeks. The concentration of bile acids in the plasma decreased when pectin was given, and with increasing degree of methylation more bile acids were excreted with the feces.

#### **5.2 Hydrocolloids and type 2 diabetes**

It has been reported that dietary soluble fiber such as β-glucan, psyllium, and guar gum decreases glucose and insulin responses to carbohydrates if taken in sufficient amounts. A study comparing the effects over 6 months of barley bread, high in β-glucan, to white bread found that barley bread improved glycemic control compared with white wheat bread in 11 men with type 2 diabetes.97 Insulin responses were increased, which hypothetically could reflect recovered β-cell function. In men with diabetes and hypercholesterolemia participating in a crossover trial, 8 weeks of psyllium (15 g/day) decreased hemoglobin A1c 6.1% (absolute change, 0.8%), with similar 6% decreases in fasting postprandial glucose (Anderson et al., 1999). Improved fasting and postprandial glycemic control was found in 11 type 2 diabetic patients taking 21 g/day of guar gum or placebo in a randomized doubleblinded crossover trial (Aro et al., 1981). Small improvements in overall glycemic control and sizable improvements in postprandial glycemia after 4 weeks of treatment in a randomized controlled crossover trial were reported by Fuessl et al. (1987) Guar gum decreased fasting blood glucose from 11.4 to 9.5 mmol/l in 19 obese patients with type 2 diabetes who were enrolled in a randomized double-blind crossover trial (Lalor et al., 1990). Guar gum (15 g/day) has also improved long-term glycemic control and postprandial glucose tolerance in 15 type 2 diabetic patients treated with guar gum over an 8-week period (Groop et al., 1993). Viscosity is an important determinant of soluble hydrocolloid in retarding glycemic responses (Wood et al., 2000).

#### **5.3 Hydrocolloids as laxative and antidiarrhea**

The laxative activity of bulk forming substances has been known since the time of Hippocrates. Hydrocolloid fractions of psyllium and ispaghula are common bulk forming

Hydrocolloids in Food Industry 37

Dongowski, G. & Lorentz, A. (2004). Intestinal steroids in rats are influenced by the structural parameters of pectin, *Journal of Nutritional Biochemistry*, vol. 15, No. 4, pp. 196-205 Fellows, P. (2000). *Food processing technology: principles and practice*, CRC press. Boca Raton,

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Foord, S.A. & Atkins, E.D.T. (1989). New x-ray diffraction result from agarose: extended single

Fuessl, H.S., Williams, G., Adrian, T.E. & Bloom, S.R. (1987). Guar sprinkled on food: effect on

Furia, T.E. (Ed.). (1980). *Handbook of food additives*, CRC press, ISBN 0849305438, Boca Raton,

Glicksman, M. (1969). *Gum Technology in the Food and Other Industries*, Academic Press, ISBN

Groop, P.H., Aro, A., Stenman, S. & Groop, L. (1993). Long-term effects of guar gum in subjects

Hollingworth, C. S. (ed.). (2010). Food Hydrocolloids: Characteristics, Properties and Structures. Nova Science Publishers, ISBN 978-1-60876-222-4, New York Holloway, W.D., Tamsan-Joens, C. & Bell, E. (1980). The hemicelluloses component of dietary

Imeson, A. (2010). *Food stabilisers, thickeners and gelling agents,* Blackwell Publishing Ltd, ISBN

Jensen, C.D., Haskell, W. & Whittam, J.H. (1997). Long-term effects of water-soluble dietary

Kuo, M.-S., Mort, A.J. & Dell, A. (1986). Identification and location of l-glycerate, an unusual acyl substituent in gellan gum. *Carbohydrate Research*, vol. 156, pp. 173–187 Labropoulos, K.C., Niesz, D.E., Danforth, S.C. & Kevrekidis, P.G. (2002). Dynamic rheology of

Landin, K., Holm, G., Tengborn, L. & Smith, U. (1992). Guar gum improves insulin sensitivity,

Lim, F. & Sun, A.M (1980). Microencapsuled islets as bioartificial endocrine pancreas. *Science*,

Melton, L.D., Mindt, L., Rees, D.A. & Sanderson G.R. (1976). Covalent structure of the

fiber in the management of hypercholesterolemia in healthy men and women.

agar gels: theory and experiment. Part II. gelation behavior of agar sols and fitting of a theoretical rheological model. *Carbohydrate Polymeres,* vol. 50, No 4, pp. 407–415 Lalor, B.C, Bhatnagar, D., Winocour, P.H., Ishola, M., Arrol, S., Brading, M. & Durrington, P.N.

(1990). Placebo-controlled trial of the effects of guar gum and metformin on fasting blood glucose and serum lipids in obese, type 2 diabetic patients. *Diabetic Medicine*,

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laxative (Fingal & Feston, 1979). The fiber from foods, such as carrots, cabbage, apple, and bran compared to guar, produces very different responses in colon function 104. Fecal weight is increased more by a bran supplement than by guar supplement. The results from a study of digestion of hemicelluloses in humans suggest that arabinoxylan is not digested and perhaps may be the active component in laxation (Holloway et al., 1980). One hypothesis for judging the value of a bulk former as a laxative concerns its ability to hold water. However, some new evidence appears to contradict this. Since the greater the water holding capacity of a fiber source, the less the effect on fecal bulk (Stephen & Cummings, 1979).

### **6. References**


laxative (Fingal & Feston, 1979). The fiber from foods, such as carrots, cabbage, apple, and bran compared to guar, produces very different responses in colon function 104. Fecal weight is increased more by a bran supplement than by guar supplement. The results from a study of digestion of hemicelluloses in humans suggest that arabinoxylan is not digested and perhaps may be the active component in laxation (Holloway et al., 1980). One hypothesis for judging the value of a bulk former as a laxative concerns its ability to hold water. However, some new evidence appears to contradict this. Since the greater the water holding capacity of a fiber

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**6. References** 


**3** 

*1,2Argentina 3Germany* 

**Different Sources** 

D. M. Cabezas1, R. Madoery2, B. W. K. Diehl3 and M. C. Tomás1

**Emulsifying Properties of Hydrolized** 

*3Spectral Service GmbH Laboratorium für Auftragsanalytik, Cologne* 

*Plata – CONICET - Facultad de Ciencias Exactas (FCE), Universidad Nacional de La Plata (FCE - UNLP), La Plata 2Cátedra de Química Orgánica – Facultad de Ciencias Agrarias, Universidad Nacional de Córdoba (FCA - UNC), Córdoba* 

 **Sunflower Lecithins by Phospholipases A2 of** 

*1Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA) – CCT La* 

Lecithins are a mixture of acetone insoluble phospholipids, containing mainly phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), minor compounds such as phosphatidic acid (PA), and other minor substances such as carbohydrates and triglycerides (Schneider, 1989). The production of sunflower oil, in Argentina, is of utmost importance from an economic point of view (Franco, 2008). In this country, sunflower lecithin might represent an alternative to soybean lecithin because it is considered a non-GMO product, which is in accordance with the preference of some

The introduction of changes in the original concentration of these phospholipids, by chemical or enzymatic modification of their structure can lead to obtain lecithins with different physicochemical and functional properties, with respect to native lecithin (van Nieuwenhuyzen & Tomás, 2008). The modification processes usually applied on native lecithins are the fractionation with ethanol (Sosada, 1993; Wu & Wang, 2004; Cabezas et al., 2009a, 2009b) and the enzymatic hydrolysis (Schmitt & Heirman, 2007; Cabezas et al., 2011a). Native and modified lecithins are used in a wide range of industrial applications: nutritional, pharmaceutical applications, food, cosmetics, etc. (Prosise, 1985; Wendel, 2000). In the food industry, lecithin represents a multifunctional additive in the manufacture of chocolate, bakery and instant products, margarines, and mayonnaise, due to the

In particular, enzymatic hydrolyzed lecithin may present technological and commercial advantages over native lecithins: (1) enhanced O/W emulsifying property; (2) increased emulsion stability under acid conditions and in the coexistence with salts; (3) improved

characteristics of its phospholipids (van Nieuwenhuyzen, 1981).

**1. Introduction** 

consumers.

