Preservation of Tilapia (Oreochromis aureus) Fillet by Isochoric (Constant Volume) Freezing

Abstract

ABSTRACT The aim of this work was to evaluate the effects of isochoric freezing on the quality of tilapia fillet. Isochoric freezing was compared to chilling, super-chilling, and freezing. Isochoric freezing showed muscle color alterations similar to the other preservation methods. All preservation methods resulted in softer fillets, with the isochoric frozen fillet having the most similar texture to that of the fresh sample. Thiobarbituric acid reactive substances (TBARS) for isochoric samples were similar to those of fresh samples. However, there was a 53%, 55%, and 34% increase in TBARS for chilled, super-chilled, and frozen samples, respectively. Total volatile basic nitrogen (TVB-N) content was 1.4 times higher for isochoric samples than for fresh samples. For chilled, super-chilled, and frozen samples, TVB-N content was 3.0, 1.9, and 1.3, respectively, times higher than for fresh samples. Microstructural analysis indicated that isochoric samples showed less cell damage compared to those using other methods. Subfreezing temperatures in conjunction with no ice formation during isochoric freezing contributed to improved quality of tilapia fillet. This study may find application in the commercial preservation of fish to increase shelf life and allow for expanded distribution of raw fish. This study might also be a potential solution to “food desert” areas, where residents have low access to fresh healthy foods.