Page 331 - Natural Antioxidants, Applications in Foods of Animal Origin

310 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir its important fiber content but also because of its antioxidant capacity (Kang

et al., 2006; Rehman, 2006). They have a high fiber and vitamin contents
as well as other associated bioactive compounds such as flavonoids and
terpenes possessing antioxidant properties (Lario et al., 2004). According to
Saura-Calixto (1998) DF from citrus residues has good functional properties
and low caloric content. Moreover, the residues contain more natural anti-
oxidants than do the flesh or juice (Larrauri et al., 1996b).
Limonoids, the major cause of bitterness in citrus juice, have been
reported to possess substantial antioxidant and anti-cancer activities. The
anti-carcinogenic activity of limonoids has been tested successfully in labo-
ratory animals (Lam et al., 1989; Miller et al., 1989). They appear in many
forms, including nomilin, obacunone, ichangin, and limonin. Limonin and
nomilin are the most prevalent forms of the citrus limonoids. Among the
classes of phytochemicals with anti-cancer properties designated by the
National Cancer Institute of USA, carotenoids, coumarins, flavonoids, gluca-
rates, monoterpenes, and phenolic acids are present in citrus fruits (Nagy &
Attaway, 1992). They were reported in the highest concentration in citrus
peel and were mainly composed of ferulic, sinapic, coumaric, and caffeic
acids as well as hesperidin and naringin, among others (Peleg et al., 1991;
Nagy & Attaway, 1992). Citrus flavonoids have been extensively investi-
gated because of their health-promoting properties (Middleton & Kandas-
wami, 1994). Nogata et al. (1996) reported that albedo tissue extracts from
lemon, inhibited both cyclooxygenase and lipoxygenase activities more than
those in orange, which could be related to the prevention of thrombosis,
atherosclerosis, and carcinogenesis.
The chemical components of citrus fiber (pectin, lignin, cellulose, and
hemicellulose), together with other compounds, such as flavonoids, were
analyzed in nine different industrial sources (Marín et al., 2007). Final fiber
composition was found to be more dependent on the industrial process than
on the type of citrus. The chemical changes gone by citrus fiber showed
losses of functional values; that is, SDF and ascorbic acid content decreased
when waste products were transformed into fibers. The water holding and
lipid holding capacities of analyzed citrus fibers suggested a non-linear
behavior of these properties.
High DF powders from Valencia orange and Persa lime peels were prepared
and their composition and antioxidant capacity were studied (Larrauri et al.,
1996b). Fibers from both peels had high TDF content (61–69%) with an
appreciable amount of soluble fiber (19–22%). The concentration of anti-
oxidant (AA ) required to achieve a 50% inhibition of oxidation of linoleic
50
acid at 40 °C was measured using the ferric-thiocyanate method. Lime peel