Page 211 - Natural Antioxidants, Applications in Foods of Animal Origin

190 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir

5.3.2.4 MILK PROTEINS

Milk and milk components have been frequently used in the enhancement
of nutritional and technological properties of a wide variety of foods. A
feasible application of peptides or hydrolysates as antioxidants is being
explored especially in muscle foods. The phosphorylated caseinophospho-
peptides (CPP) have the ability to scavenge free peroxyl radicals as well
as to chelate transition metals such as iron, copper, and zinc (Kim et al.,
2007). This is positively correlated with the amounts of histidine, lysine,
proline, and tyrosine. Incorporation of casein calcium peptides (2%) inhib-
ited about 70% of lipid oxidation and prevents formation of an off-color in
meat products. Rossini et al. (2009) suggested that casein peptides (20 mg/
ml) effectively inhibited lipid per-oxidation in ground meat homogenates
and mechanically deboned meat. As cooking increases the catalytic activity
of iron, the stronger chelating activity of enriched CPP may make them
more effective antioxidants in cooked muscle foods (Diaz & Decker, 2004).
Whey hydrolysates may also act as potential antioxidants in meat prod-
ucts. Pena-Ramos and Xiong (2003) evaluated the AOA of selected whey
hydrolysates in cooked pork patties. The results indicated that at an appli-
cation level of 2%, the whey protein isolates and their hydrolytic products
not only reduced the cooking loss but also suppressed lipid oxidation in
cooked pork patties during refrigerated storage. Notably, hydrolysis with
protamex improved the capability of whey protein to inhibit early-stage
lipid oxidation (formation of hydroperoxides or conjugated dienes) as well
as to retard propagation of the oxidation process. Therefore, milk proteins
can be superlatively used as nutrient, color enhancer as well as antioxidant
in processed muscle foods.

5.4 MODE OF APPLICATION OF ANTIOXIDANTS

5.4.1 DIETARY SUPPLEMENTATION

Dietary supplementation of vit. E and TC is very commonly used to improve
the meat quality. The antioxidant activities of many plants, vegetables, herbs
and their essential oils (eugenol, thymol, and carvacrol), flavonoids, cyani-
dine glycosides, etc. are also elucidated. It is considered that the AOA of
these compounds is due to their high redox properties and chemical struc-
ture, which can be responsible for neutralizing free radicals, chelating tran-
sitional metals, and quenching singlet and triplet oxygen by delocalization