Page 76 - Natural Antioxidants, Applications in Foods of Animal Origin

Natural Antioxidants: Occurrence and Their Role in Food Preservation 55
VetBooks.ir are important dietary sources of phylloquinone (Gao & Ackman, 1995;

Piironen et al., 1997; Booth & Suttie, 1998; Koivu et al., 1999; Jakob &
Elmadfa, 2000). Niger seed oil has been characterized by extremely high
level of vitamin K (0.2%) (Ramadan & Moersel, 2002). Among edible oils,
1
the best sources of phylloquinone are niger seed oil (ca 2.0 mg/g), rape-
seed oil (ca 1.5 ug/g) and soybean oil (ca 1.3 ug/g). Sunflower oil is the
poorest source (ca 0.10 ug/g) of phylloquinone (Piironen et al., 1997). Its
levels are also moderate in olive oil (Jakob & Elmadfa, 2000; Shearer et
al., 1996; Piironen et al., 1997). A study reported that in olive oil, the mean
content of phylloquinone ranged from 12.7 to 18.9 μg/100 g while in human
plasma, phylloquinone content varied between 0.22 and 0.56 ng/mL (Otles
& Cagindi, 2007). The addition of phylloquinone-rich oils in the processing
and cooking of foods that are otherwise poor sources of vitamin K (e.g.,
peanut and corn oils) makes them potentially important dietary sources of
the vitamin. The significance of dietary vitamin K has recently increased.
Blending of niger seed oil with other vegetable oils would enrich them with
vitamin K (phylloquinone) (Bhatnagar & Gopala Krishna, 2015).
1

2.9 VITAMIN C (ASCORBIC ACID)

AA (vitamin C) is considered to be one of the most powerful, least toxic
natural antioxidants. It is a water-soluble vitamin and is found in high
concentrations in many foods or plants (Table 2.3). The varied roles of
AH related to its antioxidant property in foods, browning reaction, and its
2
anaerobic loss are discussed here. AH is the trivial name for L-threo-2-hex-
2
enono-l, 4- lactone, the molecule responsible for preventing scurvy (Fig.
2.4). AH or vitamin C is ubiquitous and has multiple functions in all meta-
2
bolically active plant and animal cells. One of the principal biochemical
reactions of AH is to destroy toxic free radicals (hydroxyl and perhydroxyl)
2
resulting from the metabolic products of oxygen. In this role, the mixture
of AH and its oxidation product dehydroascorbic acid (A) is thought of
2
as a “redox buffer” (Sapper et al., 1982; Ming-Long & Paul, 1988). When
terminating free radicals, AH is converted to A, which is then recycled to
2
AH by reductase enzymes and co-factors. Besides the redox functions in
2
cells, other physiological actions of AH (Loewus & Loewus, 1987; Ming
2
& Paul, 1988) may be related to the compound’s chelation with metals and
complexing with protein (Gorman & Clydesdale, 1983; Fleming & Bensch,
1983; Ming-Long & Paul, 1988). The uses of AH , including those in food,
2
continue to increase because of the compound’s vitamin C activity, useful