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Potential Applications of Natural Antioxidants in Meat and Meat Products 105
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3.5.1.4 CITRUS FRUITS

Citrus fruits are an important source of bioactive compounds including
antioxidants such as ascorbic acid, flavonoids, phenolic compounds, and
pectins that are important to human nutrition (Fernandez-Lopez et al., 2005;
Jayaprakasha & Patil, 2007). Flavanones, flavones, and flavonols are three
types of flavonoids which are present in citrus fruit (Calabro et al., 2004).
The main flavonoids found in citrus species are hesperidine, narirutin,
naringin, and eriocitrin (Schieber et al., 2001). Epidemiological studies
on dietary citrus flavonoids improved a reduction in risk of coronary heart
disease (Di Majo et al., 2005) and are attracting more and more attention
not only due to their antioxidant potential, but also as anti-carcinogenic and
anti-inflammatory agents because of their lipid anti-peroxidation effects
(Stavric, 1993; Elangovan et al., 1994; Martın et al., 2002). In addition,
citrus by-products represent a rich source of naturally occurring flavonoids.
The peel which constitutes almost one-half of the fruit mass, contains the
highest concentrations of flavonoids in the citrus fruit (Anagnostopoulou et
al., 2006; Manthley & Grohmann, 2001).
The antioxidant effects of orange and lemon extracts were investigated
in cooked Swedish-style meatballs by Fernandez-Lopez et al. (2005). Anti-
oxidant activities of each natural extract were expressed as stability index
(SI). The SI of orange extract (1.30) was higher (P < 0.05) than that of lemon
extract (1.19). TBARS data indicated that orange extract was superior in
reducing the lipid oxidation of cooked products in comparison to lemon
extract throughout the storage period (8 ± 1 °C, 12 days). Viuda-Martos et
al. (2009) stated that the addition of citrus waste water (5, 10%) obtained
as co-product during the extraction of dietary fiber to the bologna samples
reduced the residual nitrite levels and the degree of lipid oxidation. The
flavonoids hesperidin and narirutin were detected in all the samples. Viuda-
Martos et al. (2010) studied the effect of adding orange dietary fiber (1%),
rosemary EO (0.02%), or thyme EO (0.02%) and the storage conditions on
the quality characteristics and the shelf life of mortadella, a bologna-type
sausage. Color coordinates lightness (L*) and yellowness (b*) were affected
by the fiber content. The treatments had lower level of residual nitrite; the
extent of lipid oxidation was also reduced, and analysis of the samples
revealed the presence of the flavonoids, hesperidin, and narirutin. Anti-
oxidant and antibacterial properties of Citrus paradisi fruit barks (CPFB)
extract was evaluated in turkey sausage formulation (Sayari et al., 2015).
The CPFB water extract contained a high amount of total phenolics and
flavonoids (118 ± 4 mg GAE/g dried extract and 794 ± 8.7 mg QE/g dried