**4.2 Collagen applications**

due to religious objections. Porcine collagen type I is extracted from pig hides, and in the medical field. Porcine collagen sheet material has proven to be useful as an

There are many collagen-producing companies in around the world. However,

Gelita is the world's leading supplier of hydrolysed collagen proteins for the food, health and pharmaceutical industries. Gelita is based in numerous locations around the world with its headquarters in Germany [35]. However, the collagen Gelita produces is not 100% native collagen but hydrolysed collagen, in other terms it is gelatine.

Based in Napier New Zealand, Southern Lights Biomaterials was founded in 2003. They provide high-quality processed and semi-processed biomaterials to medical device manufacturers across the globe. One of their flagships processed products is polymeric collagen, which is delivered to contracted customers [36]. The polymeric collagen produced by Southern Lights Biomaterials is type I collagen derived from bovine tendon and is naturally cross-linked [36]. They do not

take advantage of using cattle hides or face-pieces. Their collagen is sold to

ogy for the industrial production of nano-fibre. This technology is called

Revolution Fibres produce and market nano-fibre and nano-fibre products. Based in Auckland New Zealand, Revolution Fibres has developed its own technol-

electrospinning [37]. Revolution Fibres manufacture biodegradable air filters from nano-particle sized fibres that are 'electro-spun' from collagen extracted from Hoki fish skins. They have launched a skincare range using collagen fibres to deliver plant

Waitaki Biosciences based in Christchurch New Zealand manufactures speciality

nutritional supplement ingredients from natural, biological sources. Waitaki

independent contractors without further processing.

not all of them produce 100% pure collagen but rather gelatine (hydrolysed collagen). These companies lack further innovation with the collagen, thus distributing the collagen in powder or liquid form to pharmaceutical and research industries. Therefore, extracting collagen from bovine hides and using this collagen to investigate high value applications would possibly generate huge economic

Collagen plays an important role both in the mammalian and the nonmammalian body and in its extracted form. Due to collagen's high mechanical strength, it finds applications in several different industries, ranging from

implant for reconstructive surgery [34].

*Biotechnological Applications of Biomass*

**4.1 Collagen industries**

biomedical to the food industries.

*4.1.2 Southern lights biomaterials*

*4.1.3 Revolution fibres*

extracts into the skin [38].

*4.1.4 Waitaki biosciences*

**214**

*4.1.1 Gelita*

**4. Collagen market and its applications**

potential for a product that is derived of waste materials.

Collagen has been widely used in a range of applications in cosmetic, biomedical, pharmaceutical, film industries, tissue engineering and recently in 3D/bio-printing.

#### *4.2.1 Biomedical uses of collagen*

i. Collagen sponges

The collagen sponges act as a biological absorbance material. They have been useful in the treatment of severe burns and as a dressing for pressure sores, leg ulcers and donor sites. Collagen sponges can absorb large quantities of tissue exudate, smooth adherence to the wet wound bed with preservation of low moist climate as well as shielding against mechanical harm and bacterial infection [41].

Collagen sponges have also been found to be effective as drug delivery systems. For example, the collagen sponges were found to be suitable for short term delivery of antibiotics, such as gentamicin [42].

ii. Collagen shields

Originally, collagen shields were designed for bandage contact lenses. However, it's mostly used as a delivery device and has led to the development of drug delivery systems for ophthalmic applications [43]. For example, the collagen corneal shield is produced from porcine sclera tissue that closely resembles collagen molecules of the human eye. The collagen corneal shield promotes epithelial healing after corneal transplantation [44].

iii. Collagen mini pellets

A mini pellet made from collagen is usually a rod with a diameter and length of 1 mm and 1 cm respectively. These are very useful as a drug delivery device. This is because the mini pellet (rod) is small enough to be injected into the subcutaneous space through a syringe needle and still spacious enough to contain large molecular weight protein drugs, such as interferon [42].

iv. Skin replacement

Collagen has been widely used as vehicles for transportation of cultured skin cells or drug carrier for skin replacement and burn wounds [45]. Type I collagen is suitable for skin replacement and burn wounds due to their mechanical strength and biocompatibility [7].

gelatine and many other natural renewable polymers [53, 54]. Due to rising environmental concerns, biodegradable films have attracted considerable attention especially from the food and drug packaging industries as they in constitution with other natural polymers can potentially replace plastic films which are derived from

Due to collagen being a biodegradable, biocompatible and a non-toxic polymer it

One of the main applications of collagen films in the biomedical industry is as a

Edible films and coatings are a category of packaging materials. They differ from other bio-based packaging materials, and conventional packaging, by being formed from edible ingredients. These films and coatings may be used to reduce the amount of synthetic packaging used in a product or allow conversion from a multi-layer, multi-component packaging material to a single component material. The purpose of edible films and coatings may be to inhibit migration of moisture, oxygen, carbon dioxide and or to improve the mechanical integrity or handling characteristics of the food. Edible films may also be used to separate different components in multicomponent foods, thereby improving the quality of the product. Edible films may also help to maintain food quality by preventing moisture and aroma uptake or loss

The use of natural polymers such as collagen for film preparation has many advantages over synthetic and petroleum-based polymers. Biopolymer films for the purpose of packaging materials have the advantages of biodegradability, renewability, and environmental compatibility. Collagen also has good film-forming properties, high tensile strength, good thermal stability, and the fact that the collagen is derived from waste hide off-cuttings presents a sustainable solution. One drawback of collagen-based films is the inflexibility of films. However, this can be overcome by the addition of plasticizers to improve the flexibility and elongation (%) properties of the films. The use of plasticizers has been shown to provide improvement of films in terms of flexibility and elongation; however, this is generally at the expense of strength and stiffness. The effect of plasticiser concentration should, therefore, be investigated to identify best concentration results in the opti-

Biopolymer films made for the food industry as coatings or packaging needs to be transparent, have desirable tensile strength and elongation, it should be edible and possibly have a high resistance to transmission of liquids, gases and fats and oils. However, the above criteria will vary depending on the food industry

Sionkowska et al. [57] prepared biopolymer films based on blends of collagen and silk fibroin. Films were prepared by method solution casting and characterised for their mechanical properties and structure. Film blends of collagen and silk fibroin showed better mechanical properties than for pure silk fibroin films. Sionkowska et al. [57] concluded that the better mechanical properties of the blend films were due to molecular interactions between collagen and silk fibroin. No plasticizing agent was added in the preparation of collagen and silk fibroin blend films. This would result in a very brittle and stiff film due to interactions between protein chains through hydrogen bonding, electrostatic forces and hydrophobic

has been used in the meat industry to form edible films and coatings through extrusion [56]. Collagen-based films in constitution with other biodegradable materials have been prepared in several studies to be used as packaging materials. Collagen's high tensile strength and the added advantage of biodegradability makes

barrier membrane. These collagen films have been used for slow-release drug delivery and they have been used for the treatment of tissue infection, such as

synthetic polymers [55].

*Collagen: From Waste to Gold*

it an ideal agent for natural polymer films.

*DOI: http://dx.doi.org/10.5772/intechopen.94266*

infected corneal tissue or liver cancer [42].

after opening of the synthetic packaging.

mum mechanical, thermal and physical properties.

application of the film.

**217**

v. Bone substitutes

Collagen has been previously used as implantable carriers for bone inducing proteins [41]. Due to osteo-inductive activity; collagen itself has recently been used as bone substitutes [42]. Collagen combined with other polymers has been used for orthopaedic defects. Demineralised bone collagen in combination with hydroxyapatite was used as a bone graft material to treat acquired and congenital orthopaedic defects in rats [46].

vi. 3D printing and collagen

3D printing is the process of converting digital designs to threedimensional solid objects. 3D printing works by initially designing a 3D image of the desired object, with computer-aided design (CAD) [47]. The object is divided into digital cross-sections by the program so that the printer can build the object layer-by-layer. Once the specified design is sent to the 3D printer, a specific material can be chosen. Depending on the printer type, this material can be rubber, plastics, paper, metals and more [48]. However, in the case of bio-printing; bio-ink (cells) and bio-paper (collagen, nutrients) are required [49].

#### *4.2.2 Collagen and rheumatoid arthritis and osteoarthritis*

Collagen has shown to have positive effects on rheumatoid arthritis and osteoarthritis [50]. Published studies [51] have reported that ingestion of type II collagen relieves joint discomfort associated with osteoarthritis and rheumatoid arthritis. The authors also conducted a randomised trial involving 60 patients with severe active rheumatoid arthritis; a decrease in the number of swollen joints and tender joints occurred in subjects fed with type II collagen [51].

#### *4.2.3 Cosmetic applications of collagen*

Collagen has great tensile strength and being rich in proline and hydroxyproline, it is the main component of fascia, cartilage, ligaments, tendons, bone and skin. Having these properties, it is responsible for skin strength and elasticity. Its degradation leads to wrinkles that accompany ageing. Collagen has become a valuable ingredient of many cosmetic formulations. Cosmetic uses include skin and hair products. Collagen type III is predominant in young skin; it is referred to as "restructuring" collagen as it appears during the wound healing process [7]. With ageing collagen type III decreases leading to wrinkles and lines, thus moisturising creams and cosmetic injects containing collagen have become in high demand [52].

Bovine collagen has been the most widely used source for cosmetic applications. Recently, collagen from other sources such as fish skin, pigskin, and range of cattle skin has been used in the cosmetics industry. However, collagens from various sources differ in their physiochemical properties. For example, they all have different thermal stabilities, and this can affect the formulation or the shelf life of the products [3].

#### *4.2.4 Collagen films*

Thin films or biodegradable films are flexible, transparent and often strong materials derived from natural polymers such as whey protein, collagen, starch,

#### *Collagen: From Waste to Gold DOI: http://dx.doi.org/10.5772/intechopen.94266*

I collagen is suitable for skin replacement and burn wounds due to their

Collagen has been previously used as implantable carriers for bone inducing proteins [41]. Due to osteo-inductive activity; collagen itself has recently been used as bone substitutes [42]. Collagen combined with other polymers has been used for orthopaedic defects. Demineralised bone collagen in combination with hydroxyapatite was used as a bone graft material to treat acquired and congenital orthopaedic defects in rats [46].

3D printing is the process of converting digital designs to three-

dimensional solid objects. 3D printing works by initially designing a 3D image of the desired object, with computer-aided design (CAD) [47]. The object is divided into digital cross-sections by the program so that the printer can build the object layer-by-layer. Once the specified design is sent to the 3D printer, a specific material can be chosen. Depending on the printer type, this material can be rubber, plastics, paper, metals and more [48]. However, in the case of bio-printing; bio-ink (cells) and bio-paper

Collagen has shown to have positive effects on rheumatoid arthritis and osteoarthritis [50]. Published studies [51] have reported that ingestion of type II collagen relieves joint discomfort associated with osteoarthritis and rheumatoid arthritis. The authors also conducted a randomised trial involving 60 patients with severe active rheumatoid arthritis; a decrease in the number of swollen joints and tender

Collagen has great tensile strength and being rich in proline and hydroxyproline, it is the main component of fascia, cartilage, ligaments, tendons, bone and skin. Having these properties, it is responsible for skin strength and elasticity. Its degradation leads to wrinkles that accompany ageing. Collagen has become a valuable ingredient of many cosmetic formulations. Cosmetic uses include skin and hair products. Collagen type III is predominant in young skin; it is referred to as "restructuring" collagen as it appears during the wound healing process [7]. With ageing collagen type III decreases leading to wrinkles and lines, thus moisturising creams and cosmetic injects containing collagen have become in high demand [52]. Bovine collagen has been the most widely used source for cosmetic applications. Recently, collagen from other sources such as fish skin, pigskin, and range of cattle skin has been used in the cosmetics industry. However, collagens from various sources differ in their physiochemical properties. For example, they all have different thermal stabilities, and this can affect the formulation or the shelf life of the products [3].

Thin films or biodegradable films are flexible, transparent and often strong materials derived from natural polymers such as whey protein, collagen, starch,

mechanical strength and biocompatibility [7].

v. Bone substitutes

*Biotechnological Applications of Biomass*

vi. 3D printing and collagen

(collagen, nutrients) are required [49].

*4.2.2 Collagen and rheumatoid arthritis and osteoarthritis*

joints occurred in subjects fed with type II collagen [51].

*4.2.3 Cosmetic applications of collagen*

*4.2.4 Collagen films*

**216**

gelatine and many other natural renewable polymers [53, 54]. Due to rising environmental concerns, biodegradable films have attracted considerable attention especially from the food and drug packaging industries as they in constitution with other natural polymers can potentially replace plastic films which are derived from synthetic polymers [55].

Due to collagen being a biodegradable, biocompatible and a non-toxic polymer it has been used in the meat industry to form edible films and coatings through extrusion [56]. Collagen-based films in constitution with other biodegradable materials have been prepared in several studies to be used as packaging materials. Collagen's high tensile strength and the added advantage of biodegradability makes it an ideal agent for natural polymer films.

One of the main applications of collagen films in the biomedical industry is as a barrier membrane. These collagen films have been used for slow-release drug delivery and they have been used for the treatment of tissue infection, such as infected corneal tissue or liver cancer [42].

Edible films and coatings are a category of packaging materials. They differ from other bio-based packaging materials, and conventional packaging, by being formed from edible ingredients. These films and coatings may be used to reduce the amount of synthetic packaging used in a product or allow conversion from a multi-layer, multi-component packaging material to a single component material. The purpose of edible films and coatings may be to inhibit migration of moisture, oxygen, carbon dioxide and or to improve the mechanical integrity or handling characteristics of the food. Edible films may also be used to separate different components in multicomponent foods, thereby improving the quality of the product. Edible films may also help to maintain food quality by preventing moisture and aroma uptake or loss after opening of the synthetic packaging.

The use of natural polymers such as collagen for film preparation has many advantages over synthetic and petroleum-based polymers. Biopolymer films for the purpose of packaging materials have the advantages of biodegradability, renewability, and environmental compatibility. Collagen also has good film-forming properties, high tensile strength, good thermal stability, and the fact that the collagen is derived from waste hide off-cuttings presents a sustainable solution. One drawback of collagen-based films is the inflexibility of films. However, this can be overcome by the addition of plasticizers to improve the flexibility and elongation (%) properties of the films. The use of plasticizers has been shown to provide improvement of films in terms of flexibility and elongation; however, this is generally at the expense of strength and stiffness. The effect of plasticiser concentration should, therefore, be investigated to identify best concentration results in the optimum mechanical, thermal and physical properties.

Biopolymer films made for the food industry as coatings or packaging needs to be transparent, have desirable tensile strength and elongation, it should be edible and possibly have a high resistance to transmission of liquids, gases and fats and oils. However, the above criteria will vary depending on the food industry application of the film.

Sionkowska et al. [57] prepared biopolymer films based on blends of collagen and silk fibroin. Films were prepared by method solution casting and characterised for their mechanical properties and structure. Film blends of collagen and silk fibroin showed better mechanical properties than for pure silk fibroin films. Sionkowska et al. [57] concluded that the better mechanical properties of the blend films were due to molecular interactions between collagen and silk fibroin. No plasticizing agent was added in the preparation of collagen and silk fibroin blend films. This would result in a very brittle and stiff film due to interactions between protein chains through hydrogen bonding, electrostatic forces and hydrophobic

interaction [58]. Hence the per cent elongation values of the film blends were very low (0.30–5.10%) [57].

In order to dissolve mature collagen, pepsin enzyme can be added to the acetic acid solution, which attacks and cleaves the unwounded part of tropocollagen, allowing

The following sub-sections discuss the main extraction steps/parameters or var-

To prevent collagen denaturation and contamination, majority of the researchers

Once the collagen source is de-haired, sized and cleaned it is then processed for defatting. Majority of collagen extraction processes defat the tissue of interest with

Contaminating proteins need to be removed after defatting and demineralization. Most collagen extraction methods utilise salt or alkali solutions to solubilise the contaminants. Collagen is a lot more chemically resistant than most other proteins

**Collagen source Temperature (°C) Reference** Bovine 4 °C [14, 61–65] Fish 4–9°C [61, 62, 66–72]

**Source Solvent Reference** Bovine Acetone [19, 65]

> 10% butyl alcohol 15% Butyl Alcohol

**Collagen source Chemical Reference**

Fish 0.5 M EDTA [74]

0.5 M EDTA

[69, 73] [72, 74] [75]

> [64] [76]

therefore, it is much less likely to be degraded or solubilised by a weak salt

carry out the collagen extraction process at approximately 4°C. Contamination occurs due to thermal denaturation or microbial degradation (**Table 3**).

an organic solvent or detergent prior to extraction (**Tables 4** and **5**).

the tropocollagen units to separate and dissolve [59].

iables in more detail.

(**Table 6**).

**Table 3.**

**Table 4.**

**Table 5.**

**219**

**5.2 Temperature control**

*Collagen: From Waste to Gold*

*DOI: http://dx.doi.org/10.5772/intechopen.94266*

**5.3 Fat removal and demineralisation**

**5.4 Non-collagenous protein removal**

*Processing temperatures used to extract collagen.*

Fish 0.5% detergent

*Solvents used for de-fatting of collagenous tissue in literature.*

Bovine 0.5% HCl

*Chemicals used for demineralisation in literature.*

Not all collagen extraction methods result in a collagen product that will be suitable for film preparation. Hence, to develop a collagen film with desired properties, it is necessary to investigate the various processes to prepare acid/alkaline/ enzyme/acid-enzyme collagen that could easily be used as a raw material for extruded or casting of collagen-based films. O'Sullivan [6] reported that hydrochloric acid solubilisation extraction method of collagen is not favourable for the fabrication of edible films. However, acetic acid solubilisation with further processing gave a suitable collagen product as a raw material for the fabrication of edible film fabrication.
