No abstract

The effects of shrimp head protein hydrolysate (SHPH) from three species of shrimp (northern pink shrimp [Pandalus eous], endeavour shrimp [Metapenaeus endeavouri], black tiger shrimp [Penaeus monodon]) on gel forming ability and protein denaturation of lizardfish surimi during frozen storage at −25°C were evaluated. The quality of lizardfish surimi with 5% (dried matter) of any of the three SHPH or sodium glutamate (Na-Glu) was examined in terms of gel strength, whiteness, Ca-ATPase activity and the amount of unfrozen water, comparing with those of surimi without additive as the control. The residual Ca-ATPase activity and gel strength of surimi with SHPH were higher than those of the control throughout 180 days of frozen storage, regardless of shrimp species. The highest effect was found in surimi with Na-Glu. The gel strength and Ca-ATPase activity found a high positive correlation. The addition of SHPH to surimi also increased the amount of unfrozen water by approximately 1.29-1.36 fold higher than the control, however kamaboko gels of the control was significantly whiter. From these results, freeze-induced denaturation of lizardfish muscle protein could be lessened by the addition of SHPH, resulting in a high gel strength and Ca-ATPase activity.

To assess the potential utilization of shrimp waste, shrimp chitin (SC) and shrimp chitin hydrolysate (SCH) were prepared from black tiger (Penaeus monodon), endeavour (Metapenaeus endeavouri) and giant freshwater (Macrobrachium rosenbergii) prawns. E#ect of SC and SCH on the state of water and denaturation of lizard fish (Saurida wanieso) myofibrillar protein (Mf) at concentrations of /ῌ (dry weight/wet weight) were assessed based on water activity (Aw) and changes in Mf Ca-ATPase activity during dehydration. The e#ect was compared with untreated Mf (control) and Mf containing glucose. The Aw of Mf for each SCH was remarkably lower than the Mf with SC and control. The Mf with SCH showed a remarkably high level of inactivated Ca-ATPase activity, followed by Mf with SC and the control. Mf with glucose showed slightly higher inactivated Ca-ATPase activity than SCH, reaching Aw levels of *.0/, before rapidly decreasing. These findings revealed that SCH contributed to the retardation e#ect on dehydration-induced denaturation of Mf by stabilizing hydrated water molecules surrounding the Mf.

Effect of sugar on changes in the denaturation of fish myofibrillar protein and the state of water during frozen storage KATSUMI SAKAGUCHI1,YUSUKE SHIKU2 and YUKINORI NOZAKI3 1Industri al Technology Center of Nagasak,