Page 385 - Natural Antioxidants, Applications in Foods of Animal Origin

364 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir ascorbyl palmitate (4). BHA and BHT have synergistic effects, and when

added together at a given total concentration they are more effective than
either antioxidant alone at the same level. In the described assay, BHA
and BHT added at a concentration of 0.01% each, show an AF value of
12, similar than that of DL-γ-tocopherol. In the same way, propyl gallate
increases the efficiency of BHA, but not that of BHT. Ascorbyl palmitate,
which alone shows a weak antioxidant efficiency, sustains the activity of the
DL-γ-tocopherol (Belitz et al., 2009).
Synergic effects can occur between antioxidants, but also between anti-
oxidants and another molecules present in foods that enhance the antioxi-
dant activity. These molecules called synergists are lecithin, amino acids,
citric, phosphoric, citraconic, and fumaric acids, and in general molecules
able to form complexes with the heavy metal ions. In this way, initiation of
heavy metal-catalyzed lipid autoxidation is prevented. A synergistic effect
of different nature is that exercised by phospholipids. The addition of dipal-
mitoylphosphatidylcholine (0.1–0.2%) to lard enhances the antioxidant
activity of α-tocopherol, BHT, BHA, and propyl gallate (Belitz et al., 2009).
Phosphatidylcholine, however, does not show this capacity.

9.4 MODIFIED ATMOSPHERE PACKAGING (MAP)

When not packaged, foods during storage are usually surrounded by air;
the main gases in dry air at sea level are N (78%, v/v), O (20.99%), Argon
2
2
(0.94%), and CO (0.03%) (McMillin, 2008). MAP implies the presence of a
2
barrier, normally a plastic film, that impedes the permeation for gases, water
vapor included, that allows the maintaining of a constant environment of the
desired gas composition during the food storage. Barrier bags are first filled
with the product, previously placed in a tray, and then sealed after flushing
with the selected gas mixture.
Package protects the products against deterioration, which usually
include discoloration, development of off-flavor and off-odor, nutrient
losses, texture changes, pathogenicity, and other measurable traits (Skibsted
et al., 1994). In the case of fresh meat the main objective of packaging is the
increase of shelf life which implies the maintaining the water content, color,
microbial quality, lipid stability, and palatability (Renerre & Labadie, 1993;
Zhao et al., 1994).
Gas composition of the modified atmosphere affects the most impor-
tant meat attributes during storage which are mainly color, flavor, and
microbiology.