Detecção e controle do off flavor em tilápia do Nilo (Oreochromis niloticus), por meio de depuração e defumação. / Off flavor detection and control in nile tilapia (Oreochromis niloticus) through depuration and smoking.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Currently, economic losses are a reality due to the fish off flavor provoked by the handling used in the culture and by the water quality of the fish tanks, which are not always satisfactory. Microbiological, physical-chemical and sensory evaluations of the fish were carried out in order to detect probable alterations that would compromise the fish quality. The off flavor detection, as well as, the suggestion for depuration before distribution and sale, and the use of the smoking as a way of disguising this problem were the objectives of this research. Microbiological, physical-chemical and biological analyses of the waters in the fish and the depuration ponds were performed to monitor the quality of the fish. The fish– Nile Tilapias (Oreochromis niloticus) from the area of Arthur Nogueira, in the State of São Paulo – was submitted to the depuration (3, 5 and 7 days). The fish submitted to the depuration and the control fish were compared in order to find the best depuration period. No significant differences (p>0.05) for centesimal composition, non-protein nitrogen - NNP, total base volatile nitrogen BNVT, and pH were found among the depuration periods. The depuration process provoked a more intense weight loss in the first three days for depuration. Through the sensory analyses, we could verify that the control fish presented a greater off flavor intensity than the others. The three-day depuration showed a similar statistical efficiency (F Test) than that of the five-day treatment, but differed from that of the 7-day treatment. As for the flavor attribute, the 3, 5, and 7-day treatments did not show a significant difference, statistically. The water in the fish pond presented eutrophization problems and presence of geosmine, whereas the water in the depuration pond was clear and geosmine-free. The fish that did not go through depuration (control) were submitted to smoking. Fresh fish fillets were compared to the smoked ones. As to the centesimal composition, we verified that they were significantly affected (F Test). As to non-protein nitrogen – NNP, total base volatile nitrogen – BNVT and pH, there were no significant changes (p>0.05) either among the treatments. Through sensory analysis, we verified that the fresh fish presented a more intense off flavor than the smoked ones. As to odor and flavor, there was a significant (p>0.05) difference among the treatments. The depuration process was efficient in the elimination of the off-flavor in the tilapia, for, according to our analyses, we could conclude that the ideal period for this elimination was 5 days of depuration, carried out in a pond with clean running water. When compared to the fresh fish, the smoked fish was better accepted by the panelists. The smoking process is a way of disguising the off flavor; it is a simple, inexpensive process, which can be readily adopted by producers a way of adding value to the fish.

ASSUNTO(S)

qualidade do alimento food microbiology microbiologia de alimento food analysis pond defumação depuration tanque análise de alimento cianobactéria tilápia-do-nilo smoking qualidade da água water quality nile tilapia depuração food quality cianobacteriacea

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