شناسه هاي افزوده :
رضويلر، ودود همكارطرح , نيريز نقدهي، مسلم همكارطرح , اسدپور اصالو، يوسفعلي همكارطرح , روﺣﺪا، ﯾﺎور همكارطرح , زﯾﻨﺎﻟﯽ، اﻣﯿﺮ همكارطرح , ﻣﺼﻄﻔﯽ زاده، ﺑﯿﮋن همكارطرح , ﺟﻠﯿﻠﯽ ﺣﺴﻦ، ﺣﺴﻦ همكارطرح
چكيده انگليسي :
The most studies to increase the shelf- life of fish fillets including of useing chemical methods as well as the involvement of physical and chemical agents such as sectional temperature increase, low temperature and chemical additives have been proven their harm to human health. In addition, they also create tangible changes in terms of quality. Therefore, in this research, a natural preservation method using lactic acid producing bacteria and its supernatant as bio preservative was investigated. In the processed foods industry, the food safety is an important concern due to the risk of contamination with food borne pathogenic bacteria. Therefore, minimal processed food with fewer additives is preferred by consumers. In recent years, traditional methods of processing aquatic products, such as salting, smoking, canning, have been less considered due to invention of new methods. Vacuum packaging is used to increase the fish's shelf life and enhance the quality of processed fish. Temperature control and maintenance at the freezing point need to be sure of food safety, but it must guarantee the high quality of the product. During the maintenance period, in anaerobic conditions, LAB cultures usually predominate in the crop.
This study was carried out to determine the effects of supernatant of Lactococcus lactis and its live cells to increase the shelf life of Rainbow trout fillets (O. mykiss).
The effects of lactic acid bacteria (LAB) (Lactococcus lactis subsp. lactis) and its supernatant on shelf life of vacuum packed O. mykiss fillets were determined by chemical, bacteriological and sensory values. After preparation of the bacterium from the Iranian Scientific and Industrial Research Organization, they were cultured in MRS medium. Bacteria with dilution of 106 CFU / ml and 30% and 60% of supernatant were prepared. There effects on 96 samples of 100 grams’ fish fillets using of immersion method at 4°C was investigated and sensory test of fish fillets were evaluated using Watts et al.,1989.
The results showed that the logarithmic average of psychrophilic, psychrotrophic, mesophilic bacteria, mold and yeast in grams of fillet was significantly lower than that of control (which exceeded the log limit of human (7 CFU / g) (P<0.05) and Also, the effects of lactic acid producing bacteria and supernatant on reduction of chemical factors (TBARS, TVN, PV) was also significantly increased (P<0.05) but, the pH factor was not significantly decreased (P> 0.05). Sensory tests (odor, taste, texture and color) were tested and showed no significant difference (p> 0.05) except for pure bacteria. The bacteriological results showed that the 60% supernatant and live bacteria were more effective than that of 30% and control (p<0.05). The amounts of corrosive bacteria in 60% and live cells in storage time were less than human consumption limits (7log CFUg-1), whereas in control and 30% supernatant treatments were more than those limits.
In terms of taste, the supernatant and pure bacteria were at a good level at the end of day 15 but other treatments were in non-consumable condition. But there was a significant difference among treatments (P˂0.05).
كليدواژه :
لاكتوكوكوس لاكتيس , ماهي قزل آلاي رنگين كمان , فساد ميكروبي , فساد شيميايي , خصوصيات حسي
