Page 176 - Natural Antioxidants, Applications in Foods of Animal Origin

Natural Antioxidants: Control of Oxidation in Fish and Fish Products 155
VetBooks.ir identified 5-(ϭ-tocopheroxy)-d-tocopherol as an antioxidant obtained from

tempeh fermented by Rhizopus oligosporus. Gallic acid has been isolated
from cultures of Penicillium and Aspergillus and is known as a phenolic acid
found in many natural sources including microbial products. Methylenebis
(5-methyl-6-tert-butyl-phenol) has been identified as an antioxidant from
Penicillium janthinellum. Eurotium species have also been found to produce
several antioxidants. Three of the seven metabolites were found to have
antioxidant activity and were identified as dihydroauroglaucin, auroglaucin,
and flavoglaucin. Furthermore, Atroventin was isolated from Penicillium
paraherquei and found to have good antioxidant activity. Demethylnaph-
terpin and Carazostatin are free radical scavengers isolated from Strepto-
myces chromofucus and Streptomyces prunicolor, respectively (Shin-Ya et

al., 1992).
Carotenoids are also group of antioxidants that can be synthesized by
microorganisms. Nelis and Leenheer reported that lycopene from Blakeslea
trispora and Streptomyces chrestomyceticus, subsp. rubescens and β-carotene
from B. trispora and Duniella salina were approved for human foods as
colorants (Johnson & Schroeder, 1996). Also, astaxanthin from microbial

sources, for example, Xanthophyllomyces dendrorhous, found to have excel-
lent singlet oxygen quenching activity has been approved for use in fish
foods. The antioxidant activity of carotenoids including lutein, β-carotene,
and astaxanthin was confirmed using a fluorometric assay (Naguib, 2000).

The use of microbial fermentation as a method for producing natural antioxi-
dants has promise; therefore, more work is needed to optimize production
conditions.

4.5 APPLICATION OF NATURAL ANTIOXIDANTS IN FISH
PRODUCTS

The necessity to stabilize food against oxidation was realized before World
War II and, surprisingly, natural antioxidants have been in use because
synthetic antioxidants for edible uses were not yet available at that time
(Musher, 1944). However, composition and efficiency of the natural prep-
arations were found extremely variable and their activity was considered
insufficient. This led to the invention of synthetic antioxidants which were
chemically pure, possessed antioxidant activity, tested for safety, then made
readily available in the market. However, natural antioxidants isolated
from herbs, tea, grapes, and seeds have gained interest as replacement for
synthetic antioxidants (Samaranayaka & Li-Chan, 2011). They are readily