Mehri Zolfaghari; Eshagh Zakipour Rahimabadi; Mahin Rigi; Majid Alipour
Abstract
Introduction: Seafood is among the very perishable foodstuffs. For this reason, a lot of researches have focused on improving the quality of fish and increasing the shelf-life of fishery products, including the use of edible films, modified atmosphere, freezing and control of temperature. Storage in ...
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Introduction: Seafood is among the very perishable foodstuffs. For this reason, a lot of researches have focused on improving the quality of fish and increasing the shelf-life of fishery products, including the use of edible films, modified atmosphere, freezing and control of temperature. Storage in the refrigerator is one of the methods used in fish supply centers to keep quality and extend the product shelf-life. The storage of fish and seafood in the refrigerator decreases the enzymatic and chemical activity and activity of microorganisms. However, undesirable changes occur during refrigerator storage, which leads to a decrease in quality. Therefore, it is necessary to maintain the product quality by combining protective factors. The aim of the present study was to evaluate the preservation effects of salt/sugar solutions treatment on quality of fish fingers made from silver carp (Hypophthalmichthys molitrix) fillets during refrigerated storage (4ºC). Materials and methods: The prepared fillets (about 100 g in weight) were soaked in cold 10% salt/sugar solutions for 30 min, allowed to drain for 15 min in refrigerator and after bone separation were minced. Fish fingers were prepared after adding the ingredients and mixing, and then packaged and stored in refrigerator for 15 days. The treatments of study were as: fish fingers without any treatment (control sample), samples made from treated fillet with salt/sugar solution(50 / 50) (T2), samples made from treated fillet with salt/sugar solution (75 / 25) (T3) and fish fingers made from treated fillet with salt solution (100 %) (T4). Physicochemical, microbial (TVC and PTC) and sensory characteristics were measured at days 0, 3, 6, 9, 12 and 15. Results and discussion: PV, TBA and TVB-N values were increased significantly in all treatments (p<0.05). Lowest TVC count was obtained in treatment 2 at day 15 (5.8 log CFU/g). According to the obtained results, treatment 2 was the best treatment in sensory characteristics. Osmotic treatment increased the shelf-life of fillets and their products, due to the effect of preventing these solutions against the growth of spoilage bacteria, which ultimately resulted in the reduction of corrosive products such as TBA and TVB- N. The results of this study showed that osmotic solutions have the potential to replace the thermal and chemical treatments to produce a quality and healthy product with an apparent consumer sentiment.
Mir-Hassan Moosavy; Nassim Shavisi
Abstract
Nisin, belonged to type-A lantibiotcs, is a well-known bacteriocin that applied as natural preservative in food productions such as milk and cheese. This peptide has an inhibitory effect on many of Gram-positive bacteria. Using of nisin alone and in combination with other hurdles may serves as an effective ...
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Nisin, belonged to type-A lantibiotcs, is a well-known bacteriocin that applied as natural preservative in food productions such as milk and cheese. This peptide has an inhibitory effect on many of Gram-positive bacteria. Using of nisin alone and in combination with other hurdles may serves as an effective method to eliminate Listeria monocytogenes and other pathogens in food industries. This study was undertaken to evaluate the effect of nisin against listeria monocytogenes in different temperatures (4, 9 and 14°C), pH (5, 6 and 7) and NaCl concentrations (0, 1, 2 and 4).The minimum inhibitory concentration (MIC) of nisin was assessed using a broth micro-dilution method. Furthermore, differences in population (DP) assay was used in order to analyze the effects of (storage) temperature, pH and sodium chloride concentration on Listeria monocytogenes survival in presence of nisin. The MIC value of nisin was 320IU/ml. The effectiveness of nisin was increased at 14°C better than at 9 and 4°C (P<0.016).Nisin activity increased in the presence of 2 and 4 g/100 ml of NaCl concentration (P<0.001). Also higher inactivation was observed after to pH 5 compared to pH 6 and 7 (P<0.001). Our results demonstrated that among different NaCl, pH, temperature and nisin values, the effect of NaCl was confounded than the effect of other factors at all prepared combinations (P<0.001).Our findings suggest the application of hurdle technology for achieving effective control in most in food industries.
