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Full Length Research Paper
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Biochemical and textural
properties of frozen stored (-22˚C) gilthead seabream (Sparus
aurata) fillets
Maria Makri
Aquaculture
and Fisheries Department, Technological Educational
Institute of Messolonghi, Nea Ktiria 30200, Messolonghi,
Greece. E-mail:
mmakri@teimes.gr. Tel: +302631058204. Fax:
+302631058287.
Abbreviations: TBARS, Thiobarbituric acid
reactive substances; CTF, centrifugal tissue fluid;
AG, α-glucosidase; SH, sulfhydryl groups;
EGTA, Ν,Ν,Ν΄,Ν΄ -tetraacetic acid; TCA,
trichloroacetic acid.
Accepted
2 December, 2008 |
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Abstract |
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Skinned, vacuum packed post-rigor gilthead seabream
(Sparus aurata)
fillets were
stored frozen at
-22°C for up to 340 days. Sampling was carried out on fresh
fillets at days 34, 91, 183, 266 and 340 of frozen storage.
Tests related to muscle integrity (activity of α-glucosidase
and the protein content of centrifugal tissue fluids),
myofibrillar protein denaturation
(Ca2+- and Mg2+-ATPase activities in
actomyosin extracts)
and lipid degradation products (free
fatty acids, peroxide values and thiobarbituric reactive
substances) showed that storage time affected
the integrity of muscles, and caused structural changes to
myosin (or ‘actomyosin’)
and hydrolysis and oxidation of lipids. A slight decrease in
salt soluble proteins was observed after 266 days of frozen
storage suggesting that storage time hardly affected the
formation of aggregates. The water holding capacity of the
stored frozen fillets decreased with storage time and was
associated with the damage in muscle structures
(protein content in centrifugal tissue fluids),
denaturation of myofibrillar proteins and lipid degradation
products (free fatty acids and
peroxide value). The firmness and toughness
of the frozen fillets, as measured by the Warner-Bratzler
shear knife, increased slightly with storage time. The
changes in toughness were associated with the state of
myofibrillar proteins and changes in water holding capacity
of the stored frozen fillets.
Key
words:
Gilthead
seabream, fillets, frozen storage, quality. |
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