Comparative Analysis of Physico-Chemical Properties and Intra Specific Morphological Variation of Tumid Venus Calm Gafrarium Tumidum Populations Along North Western Coastline in Jaffna District
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Date
2013
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Uva Wellassa University of Sri Lanka
Abstract
Tumid Venus clam (Gafrarium tumidum) is one of the readily available coastal bivalves consumed by local residents in Jaffna district of Sri Lanka. Scientific data on physicochemical, sensory attributes of this species and investigate the intra-specific variations among clam populations is however scarce. Therefore, the objective of this study was to determine population structure, physicochemical and sensory attributes of Tumid Venus clam in four different sites of Jaffna lagoon at two different maturity stages.
Randomly collected 200 clams from each different sites: Karainagar (9.7481°N,
79.8829°E), Mandaitivu (9.6165°N, 79.9920°E), Kayts (9.6526°N, 79.9081°E) and
Navanthurai (9.6687°N, 80.0007°E) of Jaffna lagoon were graded into two maturity stages as mature (>35 mm) and immature (<35 mm) based on the shell length. The
composite samples were then subjected to analysis of physicochemical and organoleptic
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attributes using standard analytical protocols. Standarized morphometric parametric
parameters were subjected to discriminant function analysis (DFA). Results revealed that there was a significant difference in color a* (redness), b* (yellowness), L* (lightness), pH value, water holding capacity, moisture and ash contents with the location (p<0.05). However, maturity stage had significant effects only on color a*, b* and L* values and water holding capacity. Based on sensory evaluation, the appearance and taste of cooked clams were varied with the location and maturity stage because of the changes in water temperature, food source availability. The highest consumer acceptance was recorded for immature bivalve samples of Navanthurai. Current study showed the suitability of low cost bivalve resources as substitute for conventional, expensive seafood sources. The
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highest mean length for total shell length(VL), shell length(VH), length of hinge plate(HL) and width of hinge plate(HW) were 4.03 ± 0.02, 3.19 ± 0.02, 1.23 ± 0.01 and
0.45 ± 0.03 respectively for populations sampled from Navanthurai (Site 2). Results of
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DFA showed that morphological similarity among four populations of clams. In conclusion, location and maturity stage had a significant effect on physiochemical and sensory attributes of Tumid Venus clam.
Key words: Jaffna lagoon, Morphological variations, Physicochemical attributes, Sensory, Tumid Venus Clam
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Animal Science Degree Programme (ANS)