Physicochemical and microbiological changes in gutted and ungutted red tilapia (Oreochromis ssp) stored in ice
We assessed the degree of freshness of gutted and ungutted red tilapia (Oreochromis ssp) using physicochemical and microbiological analyses of samples of gutted red tilapia on days 0, 3, 5, 8, 11, 14 and 17 and of ungutted red tilapia on days 0, 3, 6, 9, 11, 14 and 16. The total sample size was five fish stored in ice at temperatures between 0 and 4 °C. Different methods were used to study the degree of freshness: pH, water holding capacity (WHC) and microbiological analysis (aerobic mesophilic count). Once we obtained the results, a one-way analysis of variance (ANOVA) was used to determine possible correlations between the values of deterioration and the data obtained by other analysis methods. The one-way ANOVA showed that statistically significant differences (P<0.05) were found in almost all of the parameters analyzed throughout the storage times, indicating the loss of freshness in the fish. In the gutted fish, the firmness of the fillets and the whole fish presented the most noticeable statistically significant deterioration on day eight of storage, when the six logarithmic cycles of aerobic mesophilic bacteria counts were exceeded, and the fillets presented a statistically significant deterioration of the WHC. The ungutted fish began to lose freshness that limited the consumption of the food between the third and sixth day of storage, with aerobic mesophilic bacteria counts of 7.33±1.07 Log CFU g-1 and 7.14±1.60 Log CFU g-1, respectively. Similarly, significant decreases in firmness in the fillets and abdomen were noticed on the third day of storage.