Quality Characteristics of Brined Deep Frozen Common Carp (Cyprinus carpio)

摘要

The effect of brining on the keeping quality of gutted, ungutted, gutted common Carp (Cyprinus carpio) were monitored under low storage (deep frozen) conditions of-21Oc for 8 weeks. Three treatments were used for the study viz: Treatment 1- Normal brined Carp (saturated) Treatment 2-superbrined Carp (super saturated) and treatment 3- control- (carp with no brine treatment). These were monitored through organoleptic (cooked and uncooked) and chemical tests (TVB) to indicate extent of spoilage. Weekly variations in mean weights and initial and final proximate composition of fish in each treatment were also monitored. A concurrent loss in weight was recorded form 1st- 3rd week in all the brining treatments employed and equally affects the fillets, gutted and ungutted samples. This suggests displacement of locked up water which could have accelerated spoilage in the tissue of the fish (Cypriuns corpio) by salt crystals, hence the corresponding loss in weight of the fish, weight loss was negligible in Treatment 3, the control fish without brining. The correlation efficient (r) for TVB values with length of storage were positive in all cases for gutted, ungutted, and fillttetted samples (super brine -0.80, 0.84 and 0.87), (Normal brining -0.86, 0.90 and 0.44) and (control -0.98, 0.94 and 0.62 respectively) which implies TVB values increases with the spoilage rate/ length of experimental period. However delayed production of TVB were experienced in Treatments 1 and 2 (Normal and superbrined fish) up to the end of the 5th week which suggests that brining in whatever form causes delayed responses to spoilage in deep frozer Cypriuns carpio. The much lower crude protein (6.59-15.42% (Super brine) and 9.62-13.22% (Normal brine) and higher ash content 16.85-18.78% ash (super brining) and 12.08-16.77% ash (normal brine) on proximate analysis of the final fish products for normal and supper brined fish suggests salt protein denaturation coupled with cell (tissue) damage by the frozen salt crystals. The larger surface of exposure of the fillets in Treatments 1 and 2 and there thinness compared to gulled and ungutted samples makes it a better preserved product and it is also responsible for the higher degree of saltiness. All measured parameters the organoleptic assessment (cooked and uncooked), weight loss and TVB values followed a similar pattern of variation. However, there was no delayed response in the TVB production for the control fish which commenced at the 2nd week for fillet control (4.89-24.49 mg 100 gm 1 fish), ungutted control (9.79-26.93 mg 100 gm 1 fish) compared to much lower values recorded for normal and superbrined products from the 6th-8th week. Normal brining should be done to deep frozen Cyprinus carpio to reduce the degree of saltiness to taste. However, if a more permanent product form/preparation) is desired, like it is the case if further processing to Carpfish meal, cake or paste superbrining is recommended in the fillet form to enhance a better keeping (shelflife) quality. If superbrined fish is desired for cooking immediately it should be soaked in water for at least 3 h to desalt it or if used directly little or no salt should be added.