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African Journal of Biotechnology

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The biochemical, textural and sensory properties of king scallop (Pecten maxinus) meats frozen at different characteristic freezing times

M Makri

Abstract


Post rigor scallop meats were frozen individually with characteristic freezing time of 19, 49, 89, 235, 555 and 1000 min (time to cool the thermal centre of the meats from -1 to -7°C). After freezing, the meats were thawed and their quality was evaluated with tests related to muscle integrity (-hydroxy-acylcoenzyme –A dehydrogenase activities in muscle extracts), freezing and thawing losses, expressible fluids and myofibrillar protein denaturation (Ca2+-ATPase activities in actomyosin extracts).
Instrumental texture measurements and triangular sensory evaluations were also performed. Fresh post-rigor meats were analyzed as controls. The muscle integrity test showed that the freezing process itself clearly affected the integrity of intra-cellular organelles (mitochondria). The characteristic freezing time of 89 and 49 min caused more damage to cell structure than the shorter and longer characteristic freezing time tested. Ca2+- ATPase activities of actomyosin extracts suggested that the freezing
process itself, but not the freezing time, caused structural damage to myofibrillar proteins and were associated with the changes in water holding capacity (sum of thawing and expressible fluids). Peak shear forces of fresh and frozen scallop meats, as measured by the Warner-Bratzler shear knife, showed that only the freezing process itself caused softening of scallop meats. Triangle sensory comparisons between fresh and frozen scallop muscles suggested that characteristic freezing times up to 555 min may not influence the sensory quality of frozen scallop meats. Freezing of meats at the short freezing time of 19 min reduced freezing and thawing weight losses compared to longer time tested.



AJOL African Journals Online