*2.1.1 Chemical composition and structure of polyphenols*

Dietary polyphenols has been a most exotic topic in modern food chemistry not only as structural diversity and major plant secondary metabolites, but also as compounds that express a wide range of applications in various aspects of commercial as well as general public interests [27]. The importance of their molecular structure lies in the fact that the molecular size, the parent structure, degree of polymerization or glycosylation, solubility, hydrophobicity, isomer configuration and conjugation with other phenolics [5, 34, 60, 69, 70] have a strong impact on their bio-accessibility and bioavailability. Most of the polyphenols, especially those containing adjacent dihydroxyl groups (e.g. catechins and procyanidins) are especially prone to polymerization and loss through oxidation [71]. Relatively, simple phenolic derivatives such as phenolic acids (e.g., gallic acid, caffeic acid, vanillin, and coumaric acid) and flavonoids including isoflavones are readily absorbed through the gut tract that are followed by catechins, flavanones, and quercetin glucosides [34]. On the contrary, proanthocyanindins which are compounds of high molecular weight are very poorly absorbed as well as galloylated tea catechins and the anthocyanins [34, 60]. Among the various poly-phenol compounds, reported bioavailability is so highly variable that the highest bioavailability has been reported for isoflavones, followed by flavanols, flavanones and flavonol glycosides, while the proanthocyanidins, flavanol gallates and anthocyanidins are the most poorly absorbed [34, 49, 51, 61, 72].

#### *2.1.2 Food matrix*

*Bioactive Compounds - Biosynthesis, Characterization and Applications*

the real biologic potential effect it is crucial to know the quantity of polyphenols properly released from food matrix during gastrointestinal digestion, which is the potential absorption of polyphenols to be available for subsequent metabolic pathways. This parameter is known as bio-accessibility, which can be defined as: "the fraction of a bioactive compound within the food matrix where it is contained, that has the potential to be bio-available and reach systemic circulation; this means that it has been released from the food matrix by the action of digestive enzymes [46, 52, 56, 57]. Potentially, bioavailability refers to the fraction of the bioaccessible ingested nutrient, either parent compound or active metabolite that reaches the systemic circulation and becomes available at the site of the action where it can exert biologic effects [46, 52, 58, 59]; in the case of polyphenols, this is the amount of polyphenols which can be absorbed and exert effects on specific tissues. As per this principle, bioavailability is a process that depends on the intrinsic and extrinsic factors of the host; this means that, the process depends on the food matrix ingested and the gastrointestinal conditions within the individual. Investigations have revealed which the bioavailability of polyphenols contains seven main digestive processes: (1) the release of polyphenols from food matrix (bio-accessible polyphenols); (2) changes in polyphenols during gastric and small intestine digestion conditions; (3) the cellular uptake of aglycones and conjugated forms of polyphenols; (4) microbial metabolism conjugated non-bio-accessible fraction polyphenols by the colonic micro-biota; (5) phase I (oxidation, reduction and hydrolysis) and particularly phase II (conjugation) bio-transformations in the enterocytes and then the hepatocytes, followed by generating methyl, glucuronide and sulfate derivatives; (6) transit to systemic circulation and tissue distribution; (7) urinary excretion or excretion back into the gut via bile and pancreatic juices [52, 57, 60]. Numerous studies have pointed out that the bioavailability of polyphenols is rather low and the magnitude of the relative urinary excretion of the intake fluctuates from 0.3% for anthocyanins to 43% for isoflavones that demonstrates the great variability in the bioavailability from one poly-phenol to another and the most abundant dietary poly-phenol was not necessarily the one leading to the highest levels of active metabolites in plasma [34, 51, 61]. Consequently, to explore and to determine the mechanisms of action of dietary polyphenols and their role in disease prevention, it is crucial to understand the factors that constrain bio-accessibility and bioavailability of polyphenols, some related to the food (e.g., chemical structure of the compound, food matrix, food processing and dose) while others depend on the individual (e.g., gastric emptying, intestinal transit time, composition of the micro-biota) [58, 62, 63]. However, the discussion of factors influencing the bio-accessibility and bioavailability of polyphenols will focus on food related factors such as the polyphenols' chemical structure, the nature of the food matrix and food processing, since these are the first hurdles that polyphenols face prior to

The interested reader may consult some of the accounts of the concentration and bio-accessibility of poly-phenol compounds with potential antioxidant activity as affected by simulated *in vitro* digestion; for a more detailed description, see the

Dietary polyphenols to exert their health-promoting effect need to endure the food processing conditions; second, could be released from the food matrix and become bio-accessible in the gastrointestinal tract, and then undergo metabolism and reach the target tissue of interest. As a result, chemical structure of polyphenols, nature of food matrix as well as interaction with other food constituents in

**2.1 Factors leading to degradation of polyphenols and low bioavailability**

**178**

absorption.

references [64–68].

Food products fortified with dietary poly-phenol rich extracts may lead to changes in the nutritional, chemical and rheological properties of the fortified food. Apart from potential biologic activities related to health-promoting properties, when included in a food product depending on the type of extract, the poly-phenol compounds may impart an astringent and/or bitter taste, or introduce a degree of brown coloring [5, 21, 53, 73, 74]. Concerning taste, PAs resulting from oxidative reactions are mostly responsible for some unpleasant organoleptic properties such as astringency and bitterness [51, 70, 71]. "*Astringency is a tactile sensation defined as dryness, tightening and puckering sensations perceived in the oral cavity during the ingestion of astringent molecules, mainly tannins, alums and some metal ions*" [74]. Concerning color, it is worth to note that anthocyanins are one of the most important natural pigments though they represent a problem owing to their high instability [74].

Polyphenols possess the ability to interact, both with food matrix constituents in particular carbohydrates, lipids and proteins, as well as with biologic compounds, namely proteins. All these interactions can affect the accessibility and availability both of polyphenols and other compounds as well as organoleptic properties of fortified food products and consumer acceptance. Polyphenols interact mostly to components of food matrix through non-covalent hydrophobic interactions but in the cases of interactions between polyphenols and proteins or/and carbohydrates, hydrogen bonds also contribute significantly. Nonetheless, some covalent bonds may also occur under certain food processing conditions [74]. Polyphenols form complexes with proteins that can be occurred by non-covalent interaction

(reversible), primarily driven by hydrogen bonds and hydrophobic interactions and covalent interaction (mostly irreversible) after poly-phenol activation either by oxidation, i.e. as quinones, or as carbocations resulting from proanthocyanidin cleavage under hot acidic conditions [38]. As a whole, polyphenols with elevated molecular weight and a more abundance of hydroxyl group, which provide more than one site for interaction reveal a higher affinity to interact with proteins [19, 75]. However, tannins are polyphenols capable of precipitating proteins from aqueous solutions, which are synthesized via the shikimic acid pathway [4]. In terms of non-covalent associations, amino acids (e.g., alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, tryptophan, cysteine and glycine) may react to tannins through hydrophobic interactions and hydrogen bonds. From a mechanistic point of view, the hydrogen bindings with the carboxyl group of proteins are associated with capability of the hydroxyl groups of polyphenols to donate a hydrogen atom to the nitrogen or oxygen molecule of amino acids (e.g., lysine, arginine, histidine, asparagine, glutamine, serine, threonine, aspartic acid, glutamic acid, tyrosine, cysteine and tryptophan) [19, 38]. In terms of covalent interactions, polyphenols namely tannins can be oxidized under alkaline conditions and reactive oxygen species through enzymatic and non-enzymatic oxidation reactions causing the generation of highly reactive quinone radicals. Following the oxidation step, resultant quinone radical reacts to another quinone radical that is named condensation reaction to form a dimer; a high molecular weight brown color brown color pigment named as tannin that can further interact with amino acids in a polypeptide chain through covalent binding. At the end, these dimers remain highly reactive, in turn they are re-oxidized and cross linked to another polypeptide chain [19, 73]. In this sense, research studies carried-out by Rodríguez-Roque et al., assessed impact of food matrix (water-, milk- and soymilk-fruit juice beverages) on the *in vitro* bio-accessibility of phenolic compounds and hydrophilic antioxidant activity from fruit juice-based beverages and observed that the combination of a blended fruit juice with milk or soymilk could decrease the bio-accessibility of dietary polyphenols due to the formation of complexes among these compounds and proteins of milk and soymilk though the protein precipitation could mask the poly-phenol astringent or bitter taste [67, 68, 76].

Similar to polyphenols strongly associated with proteins, evidence reveals that polyphenols can also form complexes with Carbohydrates (digestible and nondigestible) that are, highly dependent on the molecular weights of the polyphenols, the hydrophilicity of the poly-phenol, and the structure of the carbohydrate (high molecular weight, low solubility, and conformational flexibility) [75, 77]. The associations between carbohydrates and polyphenols can also affect the organoleptic properties [78] but depending on the compounds, these interactions could have positive and negative effects [74]. Besides influencing astringency perception by tannins-proteins interactions, PAs-carbohydrates associations also can lead to an astringency taste and bitterness modulation into fortified foods while tannins have less affinity to carbohydrates than to proteins due to the strong hydrogen bond formation with protein's carboxyl group. Apart from tannins, anthocyanins have the capability to interact with carbohydrates [78], in turn the association with carbohydrates could lead for, on one hand, to a lower extraction yield, and therefore lower color intensity on the final product, and on the other hand to stabilization and enhancement of anthocyanins color [74]. Interestingly, some studies reported that bioavailability of polyphenols could be reduced due to the interaction with polysaccharides [46, 52, 63, 79] while other studies revealed that polysaccharides from human diet could enhance the polyphenols' uptake [78]; however, polyphenols interactions with dietary fibers (non-digestible) are of particularly significant since non-digestible polysaccharides may play role of "ploy-phenol carrier" as an

**181**

*Electro-Spinning and Electro-Spraying as Innovative Approaches in Developing of a Suitable…*

"essential physiologic function" of polysaccharides contributing to the overall

Concerning polyphenols interactions with lipids, only a few studies have investigated the effect of dietary lipid–poly-phenol interactions on taste that have not been of special importance, except in case of plant oils—primarily the one made from olives [46, 74, 78]. In contrary, it should be highlighted that polyphenols can decrease the synthesis of fats and fatty acids in the liver, or delay their absorption in intestines [74, 78]. As reviewed, dietary polyphenols are known to form complexes with macromolecules and to affect on antioxidant values and bio-accessibility that

Apart from interactions between polyphenols and macromolecules, polyphenols are also known for their strong metal-chelating capabilities. A number of polyphenols (e.g., phenolic acids, flavonoids [79] and also tannins [80]) efficiently chelate

reactions and possess the ability to produce reactive radicals such as superoxide anion radical and nitric oxide in biologic systems [83]. This action attributed to the galloyl and catechol groups of poly-phenol compounds results in the diminution

Processing of plant foods and fortified foods with polyphenols-based functional ingredients exert a main impact on bio-accessibility of polyphenols and consequently bioavailability as well as their content and potential antioxidant activity, which depends on the type poly-phenol-rich food, the nature and location of poly-phenol compounds in the food matrix, the intensity and duration of treatment, as well as presence of components that affect absorption efficiency [46, 48, 49, 63, 69, 76, 84–88]. In overall, the bioavailability of polyphenols is determined by their bio-accessibility [89]; this means that the availability as well as accessibility of polyphenols is likely to be affected by the processing methods since food processing brings about changes in chemical composition and structure of polyphenols and in molecular interactions that have an influence on the capacity of a given compound to be extracted during digestion [69] and thus, it may also increase or diminish the bioaccessibility of such health-promoting components [76, 90] that these components may be those that are added to functional foods or are found naturally in foods such as dietary polyphenols. In other words, food processing can give rise to the degradation of polyphenols; thus, reducing their bio-accessible and non-bio-accessible fractions as well can result to chemical or physical modifications in food in such a way that fosters the release and absorption of polyphenols during digestion [69, 70]. This could be explained different effects found according to the intensity and duration of treatment depict two different scenarios including; (1) increase in the bio-accessible and non-bio-accessible contents but no effects on compounds bio-accessibility; (2) decrease in the bio-accessible and non-bio-accessible contents but a modified (increased or decreased) bio-accessibility [69, 70, 76, 90, 91]. In this sense, precise discernment of the concentration of dietary polyphenols reaching the bio-accessible fraction is much more important than the concentration of these compounds in the corresponding food products [70, 76]. Research study carried-out by Rodríguez-Roque et al. [76], assessed impact of processing [high-intensity pulsed electric fields (HIPEF); high-pressure processing (HPP); and thermal treatment (TT)] on the *in vitro* bio-accessibility of phenolic compounds and hydrophilic antioxidant activity from fruit juice-based beverages and observed an improvement up to 38% in the bio-accessibility of individual polyphenols (caffeic and p-coumaric acids from both water-fruit juice beverage (WB) and milk-fruit juice beverage (MB); chlorogenic

[26, 81, 82] that undergo redox cycling

can impair bioavailability of both polyphenols and macromolecules.

intestinal absorption of minerals and trace elements [79, 80].

*DOI: http://dx.doi.org/10.5772/intechopen.98626*

health effects of fiber-rich diets [38, 78].

trace metal ions, such as Al3+, Fe3+, and Cu+

*2.1.3 Food processing*

#### *Electro-Spinning and Electro-Spraying as Innovative Approaches in Developing of a Suitable… DOI: http://dx.doi.org/10.5772/intechopen.98626*

"essential physiologic function" of polysaccharides contributing to the overall health effects of fiber-rich diets [38, 78].

Concerning polyphenols interactions with lipids, only a few studies have investigated the effect of dietary lipid–poly-phenol interactions on taste that have not been of special importance, except in case of plant oils—primarily the one made from olives [46, 74, 78]. In contrary, it should be highlighted that polyphenols can decrease the synthesis of fats and fatty acids in the liver, or delay their absorption in intestines [74, 78]. As reviewed, dietary polyphenols are known to form complexes with macromolecules and to affect on antioxidant values and bio-accessibility that can impair bioavailability of both polyphenols and macromolecules.

Apart from interactions between polyphenols and macromolecules, polyphenols are also known for their strong metal-chelating capabilities. A number of polyphenols (e.g., phenolic acids, flavonoids [79] and also tannins [80]) efficiently chelate trace metal ions, such as Al3+, Fe3+, and Cu+ [26, 81, 82] that undergo redox cycling reactions and possess the ability to produce reactive radicals such as superoxide anion radical and nitric oxide in biologic systems [83]. This action attributed to the galloyl and catechol groups of poly-phenol compounds results in the diminution intestinal absorption of minerals and trace elements [79, 80].

#### *2.1.3 Food processing*

*Bioactive Compounds - Biosynthesis, Characterization and Applications*

poly-phenol astringent or bitter taste [67, 68, 76].

Similar to polyphenols strongly associated with proteins, evidence reveals that polyphenols can also form complexes with Carbohydrates (digestible and nondigestible) that are, highly dependent on the molecular weights of the polyphenols, the hydrophilicity of the poly-phenol, and the structure of the carbohydrate (high molecular weight, low solubility, and conformational flexibility) [75, 77]. The associations between carbohydrates and polyphenols can also affect the organoleptic properties [78] but depending on the compounds, these interactions could have positive and negative effects [74]. Besides influencing astringency perception by tannins-proteins interactions, PAs-carbohydrates associations also can lead to an astringency taste and bitterness modulation into fortified foods while tannins have less affinity to carbohydrates than to proteins due to the strong hydrogen bond formation with protein's carboxyl group. Apart from tannins, anthocyanins have the capability to interact with carbohydrates [78], in turn the association with carbohydrates could lead for, on one hand, to a lower extraction yield, and therefore lower color intensity on the final product, and on the other hand to stabilization and enhancement of anthocyanins color [74]. Interestingly, some studies reported that bioavailability of polyphenols could be reduced due to the interaction with polysaccharides [46, 52, 63, 79] while other studies revealed that polysaccharides from human diet could enhance the polyphenols' uptake [78]; however, polyphenols interactions with dietary fibers (non-digestible) are of particularly significant since non-digestible polysaccharides may play role of "ploy-phenol carrier" as an

(reversible), primarily driven by hydrogen bonds and hydrophobic interactions and covalent interaction (mostly irreversible) after poly-phenol activation either by oxidation, i.e. as quinones, or as carbocations resulting from proanthocyanidin cleavage under hot acidic conditions [38]. As a whole, polyphenols with elevated molecular weight and a more abundance of hydroxyl group, which provide more than one site for interaction reveal a higher affinity to interact with proteins [19, 75]. However, tannins are polyphenols capable of precipitating proteins from aqueous solutions, which are synthesized via the shikimic acid pathway [4]. In terms of non-covalent associations, amino acids (e.g., alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, tryptophan, cysteine and glycine) may react to tannins through hydrophobic interactions and hydrogen bonds. From a mechanistic point of view, the hydrogen bindings with the carboxyl group of proteins are associated with capability of the hydroxyl groups of polyphenols to donate a hydrogen atom to the nitrogen or oxygen molecule of amino acids (e.g., lysine, arginine, histidine, asparagine, glutamine, serine, threonine, aspartic acid, glutamic acid, tyrosine, cysteine and tryptophan) [19, 38]. In terms of covalent interactions, polyphenols namely tannins can be oxidized under alkaline conditions and reactive oxygen species through enzymatic and non-enzymatic oxidation reactions causing the generation of highly reactive quinone radicals. Following the oxidation step, resultant quinone radical reacts to another quinone radical that is named condensation reaction to form a dimer; a high molecular weight brown color brown color pigment named as tannin that can further interact with amino acids in a polypeptide chain through covalent binding. At the end, these dimers remain highly reactive, in turn they are re-oxidized and cross linked to another polypeptide chain [19, 73]. In this sense, research studies carried-out by Rodríguez-Roque et al., assessed impact of food matrix (water-, milk- and soymilk-fruit juice beverages) on the *in vitro* bio-accessibility of phenolic compounds and hydrophilic antioxidant activity from fruit juice-based beverages and observed that the combination of a blended fruit juice with milk or soymilk could decrease the bio-accessibility of dietary polyphenols due to the formation of complexes among these compounds and proteins of milk and soymilk though the protein precipitation could mask the

**180**

Processing of plant foods and fortified foods with polyphenols-based functional ingredients exert a main impact on bio-accessibility of polyphenols and consequently bioavailability as well as their content and potential antioxidant activity, which depends on the type poly-phenol-rich food, the nature and location of poly-phenol compounds in the food matrix, the intensity and duration of treatment, as well as presence of components that affect absorption efficiency [46, 48, 49, 63, 69, 76, 84–88]. In overall, the bioavailability of polyphenols is determined by their bio-accessibility [89]; this means that the availability as well as accessibility of polyphenols is likely to be affected by the processing methods since food processing brings about changes in chemical composition and structure of polyphenols and in molecular interactions that have an influence on the capacity of a given compound to be extracted during digestion [69] and thus, it may also increase or diminish the bioaccessibility of such health-promoting components [76, 90] that these components may be those that are added to functional foods or are found naturally in foods such as dietary polyphenols. In other words, food processing can give rise to the degradation of polyphenols; thus, reducing their bio-accessible and non-bio-accessible fractions as well can result to chemical or physical modifications in food in such a way that fosters the release and absorption of polyphenols during digestion [69, 70]. This could be explained different effects found according to the intensity and duration of treatment depict two different scenarios including; (1) increase in the bio-accessible and non-bio-accessible contents but no effects on compounds bio-accessibility; (2) decrease in the bio-accessible and non-bio-accessible contents but a modified (increased or decreased) bio-accessibility [69, 70, 76, 90, 91]. In this sense, precise discernment of the concentration of dietary polyphenols reaching the bio-accessible fraction is much more important than the concentration of these compounds in the corresponding food products [70, 76]. Research study carried-out by Rodríguez-Roque et al. [76], assessed impact of processing [high-intensity pulsed electric fields (HIPEF); high-pressure processing (HPP); and thermal treatment (TT)] on the *in vitro* bio-accessibility of phenolic compounds and hydrophilic antioxidant activity from fruit juice-based beverages and observed an improvement up to 38% in the bio-accessibility of individual polyphenols (caffeic and p-coumaric acids from both water-fruit juice beverage (WB) and milk-fruit juice beverage (MB); chlorogenic

and ferulic acids from MB; hesperidin and rutin from all beverages after treatments), mainly by non-thermal methods (HIPEF and HPP). On the contrary, all treatments did not change the bio-accessibility of caffeic and chlorogenic acids from soymilk-fruit juice beverage (SB), as well as naringenin from both WB and MB but diminished the bio-accessibility of ferulic acid from WB. Besides, bio-accessibility of chlorogenic and p-hydroxybenzoic acids from WB were also significantly reduced by HIPEF (between 10 and 11%) and TT (between 11 and 24%) [76]. In another research study by Ribas-Agustí et al., results clearly showed the overall decrease in bio-accessible polyphenols after pulsed electric fields treatments (1.8 and 7.3 kJ kg−1) can be linked to decreased contents in undigested apple, which was probably consequence of their degradation due to process-induced oxidative reactions [91].

Apart from bio-accessibility, polyphenols may lose their antioxidant activities or bioactivity during processing since they are oxidized easily when exposed to high temperature, oxygen and enzymes [46, 92–96], which should be taken into account when processing poly-phenol-rich food matrixes [54, 97, 98]. Dietary polyphenols are degraded at high temperature; thus, thermal treatments diminish the poly-phenol content in polyphenols-rich fortified food and jeopardize the amount of bio-available polyphenols (referring to bio-accessible fraction) due to the loss of thermo-labile phenols or their polymerization [99–101]; however, it has been shown that based on thermal processing technique used, high temperature also gives rise to other modifications turning into positive for the dietary polyphenols bioavailability such as degradation or modification of cell wall polysaccharides, proteins and other matrix factors that may lead to compounds more accessible to absorption [69, 70, 92, 95, 102, 103]. In these cases, the effect of processing can be accounted for by multiplying raw food poly-phenol content by a retention factor (RF), which describes the change in poly-phenol content for a given food due to a given process and was then calculated from the poly-phenol contents of corresponding raw and processed foods and the yield factor value [97, 104]. RFs are calculated according to Eqs. (1) and (2) as follows:

$$\text{Retention factor} \left(RF\right) = \frac{\text{concentration of polymerol in processed food}}{\text{Concentration of polymerol in raw food}} \times \text{Yield Factor}$$

(1)

**183**

**Poly-phenol components**

Hesperetin

Orange juice Orange juice Orange juice Orange juice Orange juice Orange juice Strawberry juice

Strawberry juice

Myricetin Kaempferol Ferulic acid

Milk- fruit juice

beverage

Milk- fruit juice

beverage

Milk- fruit juice

beverage

Soymilk- fruit

juice beverage

Soymilk- fruit

juice beverage

Soymilk- fruit

juice beverage

Strawberry juice

Strawberry juice

Naringenin

Orange pure juice, pasteurized 70°C,30 s

Orange pure juice, high-pressure proccessed (400 MPa/40°C/1 min)

Orange pure juice, high intensity pulsed electric fields (35 kV cm-1/750 μs)

Orange pure juice, pasteurized 70°C,30 s

Orange pure juice, high-pressure processed (400 MPa/40°C/1 min)

Orange pure juice, high intensity pulsed electric fields (35 kV cm-1750 μs)

Strawberry pure juice, pasteurized 90°C, 30 & 60 s

Strawbery pure juice, high-intensity pulsed electric fields(35 kV/cm for

1700 μs)

Strawberry pure juice, pasteurized 90°C, 30 & 60 s

Strawbery pure juice, high-intensity pulsed electric fields (35 kV/cm for

1700 μs)

Milk-fruit juice beverage, high-intensity pulsed electric fields

(35 kV cm-1800 μs)

Milk-fruit juice beverage, high-pressure processed (400 MPa/40°C/5 min)

Milk-fruit juice beverage, pasteurized 90°C,60 s

Soymilk-fruit juice beverage, high-intensity pulsed electric fields fields

(35 kV cm-1800 μs)

Soymilk-fruit juice beverage, high-pressure processed (400 MPa/40°C/5 min)

Soymilk-fruit juice beverage, pasteurized 90°C,60 s

0.66

0.66

0.66

0.00

1

[76]

0.81

0.81

0.81

0.00

1

[76]

0.81 0.82

0.82

0.82

0.00

1

[76]

0.81

0.81

0.00

1

[76]

0.89

0.89

0.89

0.00

1

[76]

1.03 1.05 0.89

0.89

0.89

0.00

1

[76]

1.05

1.05

0.00

1

[112]

1.01

1.05

0.02

2

[112]

0.9 0.93 1.00

1.00

1.00

0

1

[112]

0.90

0.95

0.03

2

[112]

0.87

0.93

0.03

2

[110, 111]

1.16

1.13

1.20

0.03

2

[110, 111]

1.00 0.91

0.84

0.99

0.07

2

[110, 111]

0.96

1.04

0.04

2

1.27

1.16

1.39

0.11

2

[110, 111]

1.03

1.00

1.07

0.03

2

[110, 111]

**Food before processing**

**Food after processing**

**Retention Factors**

**Mean RF Value**

**Min**

**Max**

**SD**

**N**

**Ref**

*Electro-Spinning and Electro-Spraying as Innovative Approaches in Developing of a Suitable…*

*DOI: http://dx.doi.org/10.5772/intechopen.98626*

[110, 111]

$$\text{Yield Factor} = \frac{weight \text{ of food after processing}}{weight \text{ of food before processing}} \tag{2}$$

Thus, the calculated values of RF < 1 indicate a reduced poly-phenol content in the processed food whereas RF = 1 and RF > 1 indicate full retention or an increase, respectively [97]. Most studies evaluating the impact of thermal and non-thermal processing on poly-phenol compounds in terms of quantity and availability have focused on traditional processing technologies such as heat-related thermal treatment (TT) and on novel emerging non-thermal techniques such as HPP, HIPEF and have used to preserve manufactured food or cooking, as well as during the food preparation, i.e. pretreatments on raw material to obtain food. Some interesting studies evaluating the effect of thermal and non-thermal treatments on retention of polyphenols and their antioxidant capacity as well as bio-availability have been conducted [84, 87, 92, 94, 98, 105–108]. The main finding concerning the impact of thermal and non-thermal processing on retention of individual polyphenols is summarized below and in **Table 1**.


#### *Electro-Spinning and Electro-Spraying as Innovative Approaches in Developing of a Suitable… DOI: http://dx.doi.org/10.5772/intechopen.98626*

*Bioactive Compounds - Biosynthesis, Characterization and Applications*

and ferulic acids from MB; hesperidin and rutin from all beverages after treatments), mainly by non-thermal methods (HIPEF and HPP). On the contrary, all treatments did not change the bio-accessibility of caffeic and chlorogenic acids from soymilk-fruit juice beverage (SB), as well as naringenin from both WB and MB but diminished the bio-accessibility of ferulic acid from WB. Besides, bio-accessibility of chlorogenic and p-hydroxybenzoic acids from WB were also significantly reduced by HIPEF (between 10 and 11%) and TT (between 11 and 24%) [76]. In another research study by Ribas-Agustí et al., results clearly showed the overall decrease in bio-accessible polyphenols after pulsed electric fields treatments (1.8 and 7.3 kJ kg−1) can be linked to decreased contents in undigested apple, which was probably conse-

quence of their degradation due to process-induced oxidative reactions [91].

Apart from bio-accessibility, polyphenols may lose their antioxidant activities or bioactivity during processing since they are oxidized easily when exposed to high temperature, oxygen and enzymes [46, 92–96], which should be taken into account when processing poly-phenol-rich food matrixes [54, 97, 98]. Dietary polyphenols are degraded at high temperature; thus, thermal treatments diminish the poly-phenol content in polyphenols-rich fortified food and jeopardize the amount of bio-available polyphenols (referring to bio-accessible fraction) due to the loss of thermo-labile phenols or their polymerization [99–101]; however, it has been shown that based on thermal processing technique used, high temperature also gives rise to other modifications turning into positive for the dietary polyphenols bioavailability such as degradation or modification of cell wall polysaccharides, proteins and other matrix factors that may lead to compounds more accessible to absorption [69, 70, 92, 95, 102, 103]. In these cases, the effect of processing can be accounted for by multiplying raw food poly-phenol content by a retention factor (RF), which describes the change in poly-phenol content for a given food due to a given process and was then calculated from the poly-phenol contents of corresponding raw and processed foods and the yield factor value [97, 104]. RFs are calculated according to Eqs. (1) and (2) as follows:

( ) Retention factor Yield Factor <sup>=</sup> <sup>×</sup> *concentration of polyphenol in processed food RF*

Thus, the calculated values of RF < 1 indicate a reduced poly-phenol content in the processed food whereas RF = 1 and RF > 1 indicate full retention or an increase, respectively [97]. Most studies evaluating the impact of thermal and non-thermal processing on poly-phenol compounds in terms of quantity and availability have focused on traditional processing technologies such as heat-related thermal treatment (TT) and on novel emerging non-thermal techniques such as HPP, HIPEF and have used to preserve manufactured food or cooking, as well as during the food preparation, i.e. pretreatments on raw material to obtain food. Some interesting studies evaluating the effect of thermal and non-thermal treatments on retention of polyphenols and their antioxidant capacity as well as bio-availability have been conducted [84, 87, 92, 94, 98, 105–108]. The main finding concerning the impact of thermal and non-thermal processing on retention of individual polyphenols is

*Concentration of polyphenol in raw food*

*weight of food after processing wieght of food before processing* Yield Factor <sup>=</sup> (2)

(1)

**182**

summarized below and in **Table 1**.


**185**

**Poly-phenol components** Clorogenic acid

Apple, Whole

apple, high-intensity pulsed electric fields fields (0.4 kV cm−1, 5 pulses

(0.01 kJ kg−1, 20 μs total treatment time)

Apple, high-intensity pulsed electric fields fields (2.0 kV cm−1, 35 pulses

(1.8 kJ kg−1, 140 μs total treatment time)

Apple, high-intensity pulsed electric fields fields (3.0 kV cm−1, 65 pulses

(7.3 kJ kg−1, 260 μs total treatment time)

*Showing retention factors for individual polyphenols in foods and beverages with the processing technologies as following: Pasteurization, High-intensity pulsed electric fields and high-pressure processed- Analysis by chromatography after hydrolysis [56] & Yield factor values collected based on USDA National Nutrient Database for Standard Reference, Release 23 [109].*

unpeeled

Apple, Whole

unpeeled

Apple, Whole

unpeeled

**Table 1.**

**Food before processing**

**Food after processing**

**Retention Factors**

**Mean RF Value**

0.88 0.58 0.33

0.33

0.33

0.00

1

[114]

0.58

0.58

0.00

1

[114]

0.75

1.02

0.13

2

[92, 114]

**Min**

**Max**

**SD**

**N**

**Ref**

*Electro-Spinning and Electro-Spraying as Innovative Approaches in Developing of a Suitable…*

*DOI: http://dx.doi.org/10.5772/intechopen.98626*


*Bioactive Compounds - Biosynthesis, Characterization and Applications*

**184**

**Poly-phenol** 

**Food before** 

**Food after processing**

**Retention Factors**

**Mean** 

**Min**

**Max**

**SD**

**N**

**RF** 

**Value**

0.87

0.87

0.87

0.00

1

[76]

**Ref**

**processing**

**components**

p-coumaric acid

Water-fruit juice

Water-fruit juice beverage, high-intensity pulsed electric fields fields

(35 kV cm-1800 μs)

Water-fruit juice beverage, high-pressure processed(400 MPa/40°C/5 min)

Water-fruit juice beverage, pasteurized 90°C,60 s

Water-fruit juice beverage, high-intensity pulsed electric fields fields

(35 kV cm-1800 μs)

Water-fruit juice beverage, high-pressure processed(400 MPa/40°C/5 min)

Water-fruit juice beverage, pasteurized 90°C,60 s

Fruit juice-soymilk beverage, high-intensity pulsed electric fields fields (35 kV cm-800 & 1400 μs)

Fruit juice-soymilk beverage,, pasteurized 90°C,60 s

Fruit juice-soymilk beverage, high-intensity pulsed electric fields fields (35 kV cm-800 & 1400 μs)

Fruit juice-soymilk beverage,, pasteurized 90°C,60 s

Fruit juice-soymilk beverage,, pasteurized 90°C,60 s

Fruit juice-soymilk beverage, high-intensity pulsed electric fields fields (35 kV cm-800 & 1400 μs)

Fruit juice-soymilk beverage,, pasteurized 90°C,60 s

0.69

0.69

0.69

0.00

1

[113]

0.97 0.89

0.79

1.00

0.1

2

[113]

0.97

0.97

0.00

1

[113]

0.87

0.87

0.87

0.00

1

[113]

0.81 0.99

0.99

1.00

0.00

2

[113]

0.81

0.81

0.00

1

[113]

0.64 0.91

0.85

0.98

0.06

2

[113]

0.64

0.64

0.00

1

[76]

0.82

0.82

0.82

0.00

1

[76]

0.78 0.69

0.69

0.69

0.00

1

[76]

0.78

0.78

0.00

1

[76]

0.91

0.91

0.91

0.00

1

[76]

beverage

Water-fruit juice

beverage

Water-fruit juice

beverage

Water-fruit juice

beverage

Water-fruit juice

beverage

Water-fruit juice

beverage

Chlorogenic acid

Fruit juicesoymilk beverage

Fruit juicesoymilk beverage

Fruit juicesoymilk beverage

Fruit juicesoymilk beverage

Fruit juicesoymilk beverage

Fruit juicesoymilk beverage

Fruit juicesoymilk beverage

Coumaric acid

Apigenin

Sinapic acid

p-hydroxybenzoic

acid

*Showing retention factors for individual polyphenols in foods and beverages with the processing technologies as following: Pasteurization, High-intensity pulsed electric fields and high-pressure processed- Analysis by chromatography after hydrolysis [56] & Yield factor values collected based on USDA National Nutrient Database for Standard Reference, Release 23 [109].*

### *Electro-Spinning and Electro-Spraying as Innovative Approaches in Developing of a Suitable… DOI: http://dx.doi.org/10.5772/intechopen.98626*
