The complex world of polysaccharides edited by Desiree Nedra Karunaratne

 

Is Chitosan a New Panacea? Areas of Application 

 

23 

Edible films are defined as a thin layer of material which can be consumed and provides a 

barrier to moisture, oxygen and solute movement for the food. The material can be a 

complete food coating or can be disposed as a continuous layer between food components 

[170]. Edible films can be formed as food coatings and free-standing films, and have the 

potential to be used with food as gas aroma barrier [171]. 

Chitosans are described in terms of the degree of deacetylation and average molecular 

weight and their importance resides in their antimicrobial properties in conjunction 

with their cationicity and their film forming properties [172]. Chitosan can form semi-

permeable coatings, which can modify the internal atmosphere, thereby delaying 

ripening and decreasing transpiration rates in fruits and vegetables [173-176].  

Films from aqueous chitosan are clear, tough, flexible and good oxygen barriers 

[177,178]. 

29. Bread 

Applications of chitosan for extension of shelf life of bread by retarding starch 

retrogradation and/or by inhibiting microbial growth have been documented. Park and 

others in 2002 investigated the effect of chitosan (493 kDa) coating on shelf life of baguette 

[179]. 

Chitosan coating may offer a protective barrier for moisture transfer through the bread 

surface, thus reducing weight loss, retarding hardness, retrogradation, inhibiting microbial 

growth, retarding oxidation [179- 181].  

30. Eggs 

Several problems are encountered during storage of eggs, such as weight loss, interior 

quality deterioration, and microbial contamination [182-183]. The movement of carbon 

dioxide and moisture from the albumen through the shell governs quality changes in 

albumen and yolk, and weight loss of [184,185].  

Chitosan coating may offer a protective barrier for moisture and gas transfer from the 

albumen through the egg shell, thus extending the shelf life of eggs [182, 186].  

31. Fruits and vegetables  

The major postharvest losses of fruits are due to fungal infection, physiological disorders, 

and physical injuries [102, 104, 187]. One of the potential approaches to extend the 

storability of these perishable commodities is to apply edible coatings on the surface, 

followed by a cold storage [188]. Edible coatings can be used as a protective barrier to 

reduce respiration and transpiration rates through fruit surfaces, retard microbial growth 

and color changes, and improve texture quality of fruits [171]. Coating fruits with 

semipermeable film has generally been shown to retard ripening by modifying the 

endogenous CO

2

, O

2

, and ethylene levels of fruits [102]. Chitosan coating is likely to modify 

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The Complex World of Polysaccharides 

 

24 

the internal atmosphere without causing anaerobic respiration, since chitosan films are more 

selectively permeable to O

2

 than to CO

2

 [189]. Therefore, chitosan coating with its ability to 

modify internal atmosphere in the tissue and fungistatic property has a potential to prolong 

storage life and control decay of fruits. 

32. Juice and beverages 

Processing of clarified fruit juices commonly involves the use of clarifying aids, including 

gelatin, bentonite, silica sol, tannins, polyvinylpyrrolidone, or combinations of these 

compounds [190]. Chitosan with a partial positive charge has been shown to possess acid-

binding properties [191] and to be effective in aiding the separation of colloidal and 

dispersed particles from food processing wastes [192,193]. These properties make chitosan 

an attractive processing aid in fruit juice production. 

33. Mayonaise  

Few studies have been conducted on the use of chitosan to enhance emulsification in 

mayonnaise preparation. Lee (1996) reported that addition of chitosan (1500 kDa, 0.1% 

based on egg yolk weight) increased emulsifying capacity of egg yolk by about 10% and 

enhanced emulsion stability of mayonnaise by 9.4% compared with those of the control 

[186]. Kim and Hur (2002) also suggested the use of chitosan as an emulsion stabilizer in 

commercial mayonnaise preparation [194]. 

Chitosan possesses a positive ionic charge and has both reactive amino and hydroxyl 

groups, which give it the ability to chemically bond with negatively charged protein. When 

pH is less than 6.5, chitosan solution carries a positive charge along its backbone. Because of 

its polar groups, chitosan also provides additional stabilization due to hydration forces 

[195]. According to Filar and Wirick in 1978, chitosan functions only in acid systems to show 

possible utility as a thickener and stabilizer [196]. 

34. Meat 

Meat or meat products are highly susceptible to lipid oxidation, which leads to rapid 

development of rancid or warmed-over flavor. Chitosan possesses antioxidant and 

antibacterial capacity [126, 197], and may retard the lipid oxidation and inhibit the growth of 

spoilage bacteria in meat during storage. 

Darmadji and Izumimoto in 1994 observed that addition of 1.0% chitosan to beef decreased 

the TBA value by about 70% compared to that of the control sample after 3 days of storage 

at 4 ◦C. Chitosan has a desirable effect on the development of the red color of beef during 

storage [198]. Sagoo et al in 2002, demonstrated that chitosan was an effective inhibitor of 

microbial growth in chilled comminuted pork products and that the effect of chitosan was 

concentration dependent [199]. 

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