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Item type:Publication, Lipid oxidation and fishy odour development in protein hydrolysate from Nile tilapia (Oreochromis niloticus) muscle as affected by freshness and antioxidants(2012-06-15); Kristinsson, Hordur G.Lipid oxidation and fishy odour development in protein hydrolysate from fresh and ice-stored Nile tilapia (Oreochromis niloticus) were investigated. During iced storage of 18 days, heme iron content decreased with a concomitant increase in non-heme iron content (P < 0.05). Peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) values increased. Phospholipid content decreased with a corresponding increase in free fatty acid content. The results suggested that lipid hydrolysis and oxidation took place during storage. When protein hydrolysates were produced from fresh and 18 days ice-stored Nile tilapia muscle, higher lipid oxidation and fishy odour/flavour along with higher amount volatile compounds were obtained in hydrolysate for unfresh sample (P < 0.05). However, the addition of mixed antioxidants during hydrolysis process markedly lowered lipid oxidation, b <sup>·</sup>, ΔC <sup>·</sup>, ΔE <sup>·</sup> values, fishy odour/flavour as well as the formation of volatile compounds in the resulting hydrolysates prepared from both fresh and unfresh samples. Therefore, hydrolysate from Nile tilapia muscle with reduced fishy odour and lighter colour could be prepared by using fresh fish and incorporation of mixed antioxidants during hydrolysis. © 2011 Elsevier Ltd. All rights reserved.2 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Instrumental textural changes in raw white shrimp during iced storage(2011-12-01); Schleining, G.The general objective of this work was to evaluate the changes in the texture of raw white shrimp, stored whole in ice for up to 14 days, by instrumental texture analysis of the flesh after peeling off the carapace. Effect of test method (relaxation, compression, texture profile analysis, cutting, and penetration tests), test speed (0.1, 0.5, and 1.0 mm/s), and test position on sample (second, third, and fourth segments of abdominal musculature) were studied to measure the textural attributes of shrimp. Mechanical parameters (force at yield point, stiffness, toughness, and shear/penetration work) increased significantly during the 14 days of storage. Shrimp muscle maintained firm texture up to 4 days of storage after harvesting. At that time, the texture became soft, stiffness of the skin layer increased, and then pH values in the shrimp reached a value higher than 7 (alkaline). A linear model with a high coefficient of determination (R <sup>2</sup> > 0.75, for all parameters obtained from the penetration test with the spherical probe) described adequately the mechanical properties of iced shrimp during storage. Comparing several methods, the penetration test on the second flesh segment using a spherical probe at a speed of 0.1 mm/s and using penetration work as a parameter gave the best results to clearly indicate the changes in textural properties of iced shrimp with a high correlation coefficient during storage time (R <sup>2</sup> = 0.83), while other test methods failed to provide an indication of deterioration. Copyright © Taylor & Francis Group, LLC.1