Summary:
The brown Venus clam Callista chione (L. 1758) is a commercially important
bivalve mollusc, naturally occurring in Mediterranean estuarine waters. Dense
beds of the animal may develop in productive areas. Like other molluscan
shellfish, C. chione are distributed live and most frequently eaten raw. So
far, most studies have focused on biological behaviour and growth rate,
population dynamics in relation to harvesting area, and the effect of dredge
design on the size and quality of the catch. Apparently, no study has examined
compositional aspects or the influence that processing and storage may have on
nutritionally important constituents of the bivalve. The aim of the present
study was to characterize the fatty acid and Carotenoid profile of raw C.
chione and to investigate changes in marinated and vacuum-packed, frozen meats,
over a storage period of four and six months and in different seasons of the
year. Live specimens of farmed C. chione were processed in boiling (100C)
water for 4 min and the cooked meats were either vacuum-packed in plastic bags
and frozen (-18oC) or used for preparing a marinade semi-preserve that was
packed in glass jars and stored at 4oC. Total lipids were extracted from the
raw and boiled meats, as well as from the samples of the frozen and marinated
products stored at 4 and 6 months, and were analysed by gas chromatography.
Data from the GC-FID analysis revealed the presence of 40 fatty acids (FA).
Saturated fatty acids (SFA) were predominant, followed by polyunsaturated
(PUFA) and monounsaturated (MUFA) fatty acids. The major SFA identified in raw
and processed C. chione were palmitic (C16:0), myristic (C14:0) and stearic
acids (C18:0). Oleic (C18:1 ω-9) and palmitoleic (C16:1 ω-7) acids predominated
among MUFA, while eicosapentaenoic (C20:5 ω-3) and docosahexaenoic (C22:6 ω-3)
were the major PUFA. Parboiling and frozen storage caused a significant (P<
0.05) increase in the ω-3/ω-6 ratio, which was accompanied by a decrease in the
MUFA/SFA, PUFA/SFA and DHA/EPA ratios. Significant changes in the fatty acid
profile were induced also by the marinating process, which appeared to have the
highest negative impact to the nutrients of the bivalve. Moreover, during
marination process, it was observed the most significant changes at the neutral
and polar lipids. Polar lipids were reduced significant while neutral lipids
were increased. Amongst carotenoids, it was observed a significant increase of
Astaxanthine after each process, leading to the conclusion that Astaxanthine
may be complexed to the protein a-croustacyanine. Thus, it may be assumed that
parboiling and freezing have no adverse effect on the fatty acid profile and
the lipid classes of C. chione as well as to the potential health benefits
arising there from.
Keywords:
Callista chione, Bivalve mollusk, Food preservation, Lipids, Carotenoids
