Page 84 - Natural Antioxidants, Applications in Foods of Animal Origin

Natural Antioxidants: Occurrence and Their Role in Food Preservation 63
VetBooks.ir and storage could reduce the PS bioactivity. Chocolate bars were prepared

containing palm oil (CONT) or 2.2 g of PS (PHYT). All samples were stored
at 20 and 30 °C during five months. A peak of hydroperoxides formation
was observed after 60 days at 20 °C and after 30 days at 30 °C. PS-enriched
samples presented higher values of hydroperoxides than control samples,
which could be attributed to the higher level of α-linolenic acid present in the
PHYT samples. All chocolate bars became lighter and softer after 90 days
of storage. However, these physical changes did not reduce their sensory
acceptability. In addition, PS bioactivity was kept during the storage, since
no significant alterations in the PS esters were observed up to five months.
However, some PS oxidation occurred in the PHYT bars, being sitostane-
triol, 6-ketositosterol, 6β-hydroxycampesterol, and 7-ketocampesterol the
major phytosterol oxidation products (POPs). The POPs/PS ratio was low
(0.001). Therefore, the dark chocolate bars developed in this study kept their
potential functionality after five months of storage at room temperature,
representing an option as a functional food (Botelho et al., 2014).

2.11 PHENOLIC COMPOUNDS

POH have aromatic hydrocarbon ring with one or more hydroxyl group.
POH contribute to the quality of edible oils by enhancing the shelf life and
flavor stability of oil (Bendini et al., 2006). Several POH have been identified
that inhibit oxidation of fats and oils by interrupting the free radical mecha-
nism of oxidation. Structural groups influencing the antioxidant activity of
POH include position and number of hydroxyl groups, polarity, solubility,
and stability of POH during processing (Soobrattee et al., 2005). Phenolics
present in fats and oils are potent antioxidants and have anticarcinogenic
properties. The antioxidant property of phenolics depends on the structure
and type of phenolics present in oil. Hydroxybenzoic acid derivatives, that
is, gallic acid, vanillic acid, and vanillin show an UV-absorption maxima
at around 280 nm while hydroxycinnamic acid derivatives, that is, caffeic,
cinnamic, p-coumaric, and ferulic acids show an UV-absorption maxima at
around 320 nm.
Virgin olive oil has a unique place among vegetable oils because of its
polyphenols and their beneficial role in human health (Visioli, 2000; Tricho-
poulou & Vasilopoulou, 2000). The polyphenols are an important class
of minor constituents linked both to the flavor of virgin olive oil and to
its keeping ability. POH present in olive oil are conventionally character-
ized as “polyphenols,” though not all of them are polyhydroxy aromatic