Effect of Smoking Methods on Shelf-Life of Rainbow Trout (Salmo gairdneri)

Authors: Nuray KOLSARICI, Özlem ÖZKAYA

Abstract: In this research, the shelf-life of vacuum-packed Rainbow trouts ( Salmo gairdneri) in 80° salinometer for 4 hours and then, treated by cold smoking (for 8 hours at 28°C) and by hot smoking (smoking was carried out in these steps: first, at 30°C for 30 minutes; second, at 50°C for 30 minutes and then, samples were cooked at 80°C for 45 minutes) was determined during the storage periods at +4±1°C and -18±1°C. Trouts stored at +4±1°C were analysed for four -day intervals till they lost their accept-ability and trouts stored at -18±1°C were analysed for one moth intervals for six months. Total mesophylic aerobic bacteria (TMAB), total psychrotrophic aerobic bacteria (TPAB) and lactic acid bacteria (LAB) counts, pH value and total volatile bases nitrogen (TVB-N) were determined. Furthermore, sensorial evaluation was done. According to the results, since the smoking temperature was high hot smoking was found more effective on preventing bacterial growth than cold smoking. At +4±1°C storage temperature, the interaction between smoking method and storage time regarding TMAB, TPAB and LAB was found significant (P<0.05). The pH values and TVB-N contens of trouts stored at +4±1°C changed sig-nificantly (P<0.05). The pH values and TVB-N contents of trouts stored at +4±1°C changed significantly (P<0.01) dependent upon smoking method and storage time. In the cold smoked samples which had high LAB growth, pH value showed a significant decrease and reached to 6.00 on the 16 th day. In this group which had higher TMAB counts than the others, TVB-N content increased raipdly. It was 50.45 mg/100 g on the 16 th day. In trouts stored at -18±1°C, pH value and TVB-N content was only effected by storage time (P<0.05). On the other hand, both storage time and smoking methods influenced the growth of TMAB, TPAB and LAB. In sen-sorial evaluation, hot smoked trouts had higher scores than cold smoked ones in both storage temperature (P<0.01). WJhile neither cold nor hot smoked trouts stored at -18±1°C did not lose their acceptability after six-month storage period, in the storage at +4±1°C cold smoked trouts spoiled on the 16 th day and hot smoked ones had a sour taste on the 44 th day and they lost their acceptability completely on the 48 th day.

Keywords: Rainbow trout, smoking, storage, shelf life

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