The antioxidant activity demonstrated by whey protein
hydrolysates suggest that, besides modifying physiological
properties of food products, these protein hydrolysates
have potential to enhance product stability by preventing
oxidative deterioration. A feasible application of
peptides or hydrolysates as antioxidants is their addition
to muscle foods, since they are subjected to rapid oxidative
reactions.
Enriched CPP, casein hydrolysates and low molecular
weight casein hydrolysates have proved to be inhibitors of
TBARS formation in cooked ground beef. The ability to
inhibit TBARS formation was highest with enriched CPP,
even though the hydrolysates had better antioxidant
activities. As cooking increases the catalytic activity of
iron, these results suggest that the stronger chelating
activity of enriched CPP may make them more effective
antioxidants in cooked muscle foods (Diaz & Decker,
2004). Casein calcium peptides showed strong antioxidant
activity against lipid oxidation in ground beef homogenates.
Incorporation of casein calcium peptides (2%)
inhibited about 70% of lipid oxidation in homogenates.
This indicates that peptides may be as useful in meat
processing as other antioxidants, helping to prevent
formation of an off-flavour in meat products, thereby
increasing shelf life (Sakanaka et al., 2005).
Whey proteins are already being utilized as functional
ingredients in meat products. Whey hydrolysates may be also potential antioxidants in meat products. Pen˜ a-Ramos
and Xiong (2003) evaluated the antioxidant activity of
selected whey hydrolysates in cooked meat pork patties.
The results indicated that at an application 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 (degradation of hydroperoxides leading to TBARS
formation). Thus, partially hydrolyzed whey proteins seem
to be particularly attractive ingredients for quality improvement
in processed muscle foods