Agriculture Reference
In-Depth Information
16.9.1.2
NATURE SEAL (NS)
NS, a cellulose-based edible coating, has been used (in combination with
antimicrobials, plasticizers, antioxidants, etc.) to coat fresh-cut apples.
This coating significantly reduced weight loss of apples more than those
treated with water solutions and was not objectionable in taste during sev-
eral weeks of storage.
16.9.1.3
CHITOSAN COATINGS
Chitosan, a by-product from crustacean shell wastes, is a high molecu-
lar weight cationic polysaccharide, normally obtained by the alkaline de-
acetylation of chitin and refers to as a range of polymers that, unlike chitin
are soluble in dilute organic acids. Chitosan-based coatings are effective
in prolonging the shelf-life and improving quality of fruits by delaying
ripening, reducing respiration rate, reducing desiccation, regulating gas
exchange, decreasing transpiration losses, modifying the internal atmo-
sphere, maintaining the quality of harvested fruits, retaining fruit firmness,
freshness, titratable acidity, soluble carbohydrates and vitamin C. It is also
highly effective in reducing decay (inhibited spore germination, germ
tube elongation, and radial growth of
B. cinerea
and
Rhizopus
species in
the culture) of strawberries, raspberries, etc. Chitosan coated berries, and
peaches were better in quality when compared to controls. The application
of chitosan coating delayed changes in contents of anthocyanin, flavonoid,
total phenolics, and reduced weight loss and browning of litchi fruit, im-
proved storability, and delayed the increase in polyphenol oxidase enzyme
activity in litchi fruit. The coating partially inhibited PPO activity of lon-
gan fruit, which is associated with peel discoloration (Jiang and Li, 2001).
16.9.1.4
CORN-ZEIN COATINGS
Zein is a natural corn protein produced from corn gluten meal and is in-
soluble in water, but soluble in aqueous alcohol, glycols and glycol esters.
It has good film- forming, binding and adhesive properties. Its water va-
por permeability is about 800 times higher than a typical shrink-wrapping
film.
