**3. Conclusion and results**

Chitosan is a versatile biopolymer that has a variety of commercial applications. However, individual research reports have used chitosans from various sources with varying physicochemical properties. Hence, the question arises as to how to globally produce chitosans with consistent properties. Each batch of chitosan produced from the same manufacturer may differ in its quality. Functional properties of chitosan vary with molecular weight and degree of deacetylation. With proper modification of chitosan, its functional properties and biological activities can be further

**275**

**Author details**

Sadik Büyükyörük

Department of Food Hygiene and Technology, Faculty of Veterinary Medicine,

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

chemical and physical processes have been used to increase its solubility.

Adnan Menderes University, Işikli, Aydin, Turkey

provided the original work is properly cited.

\*Address all correspondence to: sbuyukyoruk@adu.edu.tr

*Chitosan for Using Food Protection*

*DOI: http://dx.doi.org/10.5772/intechopen.99247*

enhanced, and more applications are being developed. Chitosan with different structures shows different biological activities and not all the biological activities are found in one kind of chitosan. Each special type of bioactive chitosan should be developed for its potential application. Moreover, many studies carried out on chitosan and chitooligosaccharide bioactivity have not provided detailed molecular mechanisms. Hence, it is difficult to explain exactly how these molecules exert their activities. Therefore, future research should be directed toward understanding their molecular-level details, which may provide insights into the unknown biochemical functions of chitosan. One major drawback of chitosan film is its high sensitivity to humidity, and thus, it may not be appropriate for use when it is in direct contact with moist foods. More research is needed to develop antimicrobial chitosan films that are less sensitive to humidity. Numerous researches conducted on food applications of chitosans have been done at a small or laboratory scale. Further research on quality and shelf life of foods, containing or coated with chitosan, should be conducted on scale-up with large volumes typical of commercial conditions.

Chitosan is a polysaccharide-based film applied to the outer surface of foods and is effective in controlling physiological, morphological, and physiochemical changes in foods. Chitosan films can control oxygen and moisture permeability and have antioxidant and antimicrobial effects on food. The most widely accepted hypotheses about the antimicrobial effect of chitosan are: 1) ionic surface interaction resulting in cell wall leakage; 2) inhibition of mRNA and protein synthesis by the penetration of chitosan into the nuclei of microorganisms; and 3) creating an external barrier, chelating metals and triggering suppression of microbial growth in essential nutrients. All of these situations are likely to occur at the same time but at different densities. The MW and DD are also important factors in determining such activity. Generally, the lower the MW and DD, the higher the effectiveness in reducing microorganism growth and proliferation. Despite the many advantages of chitosan, there are also various restrictions related to its use. The most important limitation of chitosan is its low solubility at neutral pH. To compensate for this deficiency, various

## *Chitosan for Using Food Protection DOI: http://dx.doi.org/10.5772/intechopen.99247*

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

*Studies revealing the antibacterial properties of chitosan, accordind to Olatunde et al. [43].*

*Brochothrix thermosphacta* Milk, Fruits and vegetables, Meat

*Pseudomonas aeruginosa* Meat, Sausage, Seafood *Salmonella* Enteritidis Mayonnaise, Meat, Sausage *Salmonella* Typhimurium Bread, Meat, Sausage, Seafood *Staphylococcus aureus* Bread, Meat, Sausage, Seafood

*Vibrio cholerae* Seafood *Vibrio parahaemolyticus* Seafood *Candida albicans* Seafood *Saccharomyces cerevisiae* Bread *Zygosaccharomyces baili* Juice *Aspergillus niger* Bread *Aspergillus parasiticus* Seafood *Fusarium oxysporum* Seafood *Rhizopus nigricans* Bread

*Antimicrobial activity of chitosan against some organisms in foods.*

*Listeria monocytogenes* Fruits and vegetables, Meat, Sausage, Seafood

**Microorganism Bacteria / Yeast / Mold Foods**

*Aeromonas hydrophila* Sausage, Seafood *Bacillus cereus* Meat, Seafood *Bacillus licheniformis Bacillus subtilis* Bread, Meat, Sausage

Chitosan is a versatile biopolymer that has a variety of commercial applications. However, individual research reports have used chitosans from various sources with varying physicochemical properties. Hence, the question arises as to how to globally produce chitosans with consistent properties. Each batch of chitosan produced from the same manufacturer may differ in its quality. Functional properties of chitosan vary with molecular weight and degree of deacetylation. With proper modification of chitosan, its functional properties and biological activities can be further

**Preparation method and/or foods Target microorganisms** 

Tilapia (*Oreochromis niloticus*) During the storage period of 21 days,

effect.

Sausage, Meat, Soybean Sprouts

Fruits and vegetables, Bread, Meat

**and/or findings**

total viable *Vibrio parahaemolyticus, Vibrio cholerae, Vibrio alginolyticus,* and the total coliform inhibitory effect were observed in fillets. Increasing the carvacrol concentration increased this

**Chitosan or its derivatives**

**Table 2.**

(0.125% and 0.25% w/v) carvacrol added chitosan (2% w/v)

*Clostridium historyticum Clostridium perfringens Coliform*

*Enterobacter aeromonas*

*Enterococcus faecalis Escherichia coli*

**274**

**Table 3.**

**3. Conclusion and results**

enhanced, and more applications are being developed. Chitosan with different structures shows different biological activities and not all the biological activities are found in one kind of chitosan. Each special type of bioactive chitosan should be developed for its potential application. Moreover, many studies carried out on chitosan and chitooligosaccharide bioactivity have not provided detailed molecular mechanisms. Hence, it is difficult to explain exactly how these molecules exert their activities. Therefore, future research should be directed toward understanding their molecular-level details, which may provide insights into the unknown biochemical functions of chitosan. One major drawback of chitosan film is its high sensitivity to humidity, and thus, it may not be appropriate for use when it is in direct contact with moist foods. More research is needed to develop antimicrobial chitosan films that are less sensitive to humidity. Numerous researches conducted on food applications of chitosans have been done at a small or laboratory scale. Further research on quality and shelf life of foods, containing or coated with chitosan, should be conducted on scale-up with large volumes typical of commercial conditions.

Chitosan is a polysaccharide-based film applied to the outer surface of foods and is effective in controlling physiological, morphological, and physiochemical changes in foods. Chitosan films can control oxygen and moisture permeability and have antioxidant and antimicrobial effects on food. The most widely accepted hypotheses about the antimicrobial effect of chitosan are: 1) ionic surface interaction resulting in cell wall leakage; 2) inhibition of mRNA and protein synthesis by the penetration of chitosan into the nuclei of microorganisms; and 3) creating an external barrier, chelating metals and triggering suppression of microbial growth in essential nutrients. All of these situations are likely to occur at the same time but at different densities. The MW and DD are also important factors in determining such activity. Generally, the lower the MW and DD, the higher the effectiveness in reducing microorganism growth and proliferation. Despite the many advantages of chitosan, there are also various restrictions related to its use. The most important limitation of chitosan is its low solubility at neutral pH. To compensate for this deficiency, various chemical and physical processes have been used to increase its solubility.
