Page 77 - Natural Antioxidants, Applications in Foods of Animal Origin

56 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir properties, and low toxicity. AA reacts with superoxide radical (O ), perhy-

2
droxyl radical (HO ), hydroxyl radical (HO ), and singlet oxygen (Fessenden
•
2
& Verma, 1978; Nanni et al., 1980; Cabelli & Bielski, 1983; Ming-Long
& Paul, 1988). Those reactions by AH retard lipid autoxidation. Ascorbate
2
radical is the initial oxidation product of two enzyme reactions that occur in
plants (Loewus & Loewus, 1987; Ming & Paul, 1988). Ascorbate oxidase
is the enzyme that oxidizes AH in the presence of oxygen as shown by the
2
overall reaction below:

2 Ascorbate + O → 2 Dehydroascorbic acid + 2H O
2 2
Ascorbate peroxidase is another plant enzyme that oxidizes AH , but it
2
uses hydrogen peroxide instead of oxygen as the electron acceptor.

Ascorbate + H O → Dehydroascorbic acid + 2H O
2
2
2
TABLE 2.3 Vitamin C in Selected Foods (Steinberg & Rucker, 2013).
Sources of vitamin C mg of ascorbic acid per 100 g of wet
weight or edible portion
Animal products
Cow’s milk 0.5–2
Human milk 3–6
Oysters (raw) 30
Beef, pork, veal 2–10
Beef, pork, Liver 20–30
Fruits
Apple 3–30
Banana 8–16
Blackberry 8–10
Cherry 15–30
Currant, red 20–50
Currant, black 150–200
Grapefruit 30–70
Kiwi fruit 80–90
Lemon, orange 40–50
Lime 30–45
Melon 9–60