Is Chitosan a New Panacea? Areas of Application
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35. Milk
A few attempts have been made to evaluate the possibility of using chitosan to improve the
quality and shelf life of milk. Ha and Lee in 200, investigated the effectiveness of water-
soluble chitosan (0.03%) to minimize the microbial (bacterial and yeast) spoilage of
processed milk [200]. Complete inhibition of microbial growth was observed in the banana-
flavored milk containing chitosan, in contrast to that observed in control milk (without
chitosan), during storage for 15 days at 4 and 10 ◦C. The banana-flavored milk containing
chitosan also maintained relatively higher pH than that of control milk during storage for 15
d at both temperatures [200].
36. Sausages
Sodium nitrite is generally used as a curing agent for color and flavor development as well
as preservative effect in sausages {201]. However, nitrite reacts with amine in meat and may
produce nitrosoamine, a strong toxicant detrimental to human health. Several workers [202]
have investigated the possible role of chitosan, in lieu of sodium nitrite, as curing agent in
sausage, and found that addition of chitosan could reduce or replace the use of nitrite
without affecting preservative effect and color development.
37. Seafoods and seafood products
Seafood products are highly susceptible to quality deterioration due to lipid oxidation of
unsaturated fatty acids, catalyzed by the presence of high concentrations of hematin
compounds and metal ions in the fish muscle [203]. Furthermore, seafood quality is highly
influenced by autolysis, contamination by and growth of microorganisms, and loss of
protein functionality [204].
The oxidative stability of fish flesh with added chitosans was compared with those added
with conventional antioxidants, butylated hydroxyanisole + butylated hydroxytoluene
(BHA + BHT, 200 ppm) and tert butylhydroquinone (TBHQ, 200ppm ), during storage at 4
◦C. Chitosan was most effective in preventing lipid oxidation than the others. The
antioxidant capacity of chitosan added to the fish muscle depended on the molecular
weight and concentration of chitosan [204]. Similarly, Kim and Thomas in 2007 also
observed that the antioxidative effects of chitosan in salmon depended on its molecular
weight [205].
38. Chitosan in agriculture
Due to the antifungal, antibacterial and antiviral properties of chitosan, it has been used
successfully in agriculture in recent years: in plant protection, like growth promoter, in soil
correction, enhancer of secondary metabolites production, and activator of defense
mechanisms to mention a few.
The Complex World of Polysaccharides
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39. Seed coating
Chitosan application can be done by different ways: in the seed, in the soil or by foliar way.
In seeds, it has been used as a coating material for cereals, nuts, fruits and vegetables [206-
208]. It has been shown that this way of application alters permeability of the seed plasma
membrane, increasing the concentrations of sugars and proline, and enhancing peroxidase
(POD), catalase (CAT), phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase
(TAL) activities [207,209]. By this way, germination rates increases significantly [ 210] and
seedlings germinate quicker, better, and vigorously [211-214]. Chitosan is used not only in
seed coatings, but also in fruits and vegetables, because it gives more firmness and it
promotes diminution of the normal microbiological charge [215] increasing the product life.
40. Leaf coating
Chitosan foliar application increases stomatal conductance and reduces transpiration,
without affecting plant height, root length, leaf area or plant biomass [216]. When chitosan is
sprayed in leaves, abscisic acid (ABA) content increases [217]. It promotes the activation of
defense mechanisms which allow plants to deal with stress and to defend against diseases
due to the antiviral, antifungal and antibacterial nature of chitosan [218,219].
41. Fertilizer
By applying chitosan in soil, it has been demonstrated that it stops plant wilting because it
acts as a potent fertilizer due to the high concentration of nitrogen content in its molecular
structure [220,221]. Also, it has been used as a soil amendment, controlling diseases caused
by fungal species like Fusarium acuminatum, Fusarium sp, Cylindrocladium floridanum and
Aspergillus flavus [208, 218, 222].
42. Plants growth promoter
Chitosan acts as plant growth promoter in some crops like Faba bean plant, radish,
passion fruit, potato, gerbera, cabbage, soybean and other crops when it is incorporated in
solution, increasing plant production and protecting plants against pathogens too.
Chitosan has a significant effect on growth rates of roots, shoots, flowering, and number
of flowers [219, 223].
43. Plant self defense
Plants react naturally against most of biological and environmental adverse conditions, but
sometimes defense has to be induced in order to fight against harder threats. It has been
reported that chitosan is a great biopolymer used for this purpose, because it induces
defense reactions in some plants, sensitizing them in order to increase their responses
against pathogens attack. Some substances that get favored due to the presence of chitin and