Page 341 - Natural Antioxidants, Applications in Foods of Animal Origin

320 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir particularly FA, are not evenly distributed in the wheat; most are found in

the bran (Baublis et al., 2002). According to Onyeneho and Hettiarachchy
(1992) extract of wheat bran, having high concentration of phenolic acids
and have stronger antioxidant activity than other fractions of wheat. Wheat
bran has been reported to be able to inhibit lipid oxidation catalyzed by either
iron or peroxyl radicals (Baublis et al., 2000). Zhou et al. (2004) reported
that wheat grain, bran, and fractions had different antioxidant activities and
TPCs. Their study also showed that FA was a major contributor to the anti-
oxidant activity.
Antioxidant activity of bran extracts from five wheat varieties indigenous
to Pakistan, that is, Punjab-96, Bhakkar-2002, Uqab-2000, SH- 2002, and
Pasban-90, was evaluated (Iqbal et al., 2007). All the bran extracts exhibited
appreciable TPC (2.12–3.37 mg GAE/g bran), total flavonoid content (epicat-
echin equivalent 262–304 mg/g bran), chelating activity (EDTA equivalent
597–716 mg/g bran), DPPH radical scavenging activity (51–79%), ABTS
radical cation scavenging activity (Trolox equivalent 27–36 mmol/g), oxygen
radical absorbance capacity (ORAC) (97–123 mmol/g), and TA content
(30–38 mg/kg bran). Tocopherol (22–26 ppm) and tocotrienol content
(59–74 ppm) were determined by reversed phase HPLC (RP-HPLC). It was
observed that all the varieties exhibited appreciable antioxidant potential
and significant differences were observed among the varieties in different
systems of antioxidant activity evaluation.
Four different types of wheat bran were extracted and analyzed for
phenolic acids using the Folin–Ciocalteu method and HPLC (Kim et al.,
2006). The extracts and their hydrolysis products were also evaluated for
antioxidant activities. The TPC of the red wheat bran was found higher
than that of the bran from white wheat. The majority of the phenolic acids
existed in a bound form in wheat bran. These phenolic acids can be released
by hydrolyzing the bran under alkaline or acidic conditions; however, the
former was more efficient. Ferulic, vanillic, and syringic acids were the
major individual phenolic acids in the studied wheat bran. The major portion
of the total FA was from alkaline hydrolysis. The alkaline hydrolysable frac-
tions had greater antioxidant activities, while the acid hydrolysable frac-
tions showed lower activities in both the red and white bran. The antioxidant
activity of bran extract was stronger than that of free phenolic acids.
The impact of thermal processing on antioxidant activity of purple
wheat bran, heat-treated purple wheat bran was evaluated to assess potential
health benefits (Li et al., 2007). TPC and ORAC values of sample extracts
were significantly affected by various extracting solvents. The conditions
selected for heat treatment did not markedly change antioxidant activity