Subrata Basu

Quality of Ready to Serve Tilapia Fish Curry with PUFA in Retortable Pouches

UNLABELLED Studies on the physical, chemical, and microbiological qualities of fresh tilapia meat revealed its suitability for the preparation of ready to eat fish curry packed in retort pouches. Studies on the fatty acid profile of tilapia meat suggest fortification with polyunsaturated fatty acid (PUFA) to increase the nutritional value. Based on the commercial sterility, sensory evaluation, color, and texture profile analysis F(0) value of 6.94 and cook value of 107.24, with a total process time of 50.24 min at 116 °C was satisfactory for the development of tilapia fish curry in retort pouches. Thermally processed ready to eat south Indian type tilapia fish curry fortified with PUFA was developed and its keeping quality studied at ambient temperature. During storage, a slight increase in the fat content of fish meat was observed, with no significant change in the contents of moisture, protein, and ash. The thiobarbituric acid (TBA) values of fish curry significantly increased during storage. Fish curry fortified with 1% cod liver oil and fish curry without fortification (control) did not show any significant difference in the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), during thermal processing and storage. Sensory analysis revealed that fortification of fish curry with cod liver oil had no impact on the quality. Tilapia fish curry processed at 116 °C and F(0) value of 7.0 (with or without fortification of cod liver oil) was fit for consumption, even after a period of 1-y storage in retort pouch. PRACTICAL APPLICATION Tilapia is a lean variety of fish with white flesh and therefore an ideal choice as raw material for the development of ready to serve fish products such as fish curry in retort pouches for both domestic and international markets. Ready to eat thermal processed (116 °C and F(0) value of 7.0) south Indian type tilapia fish curry enriched with PUFA and packed in retort pouch was acceptable for consumption even after a storage period of 1 y at ambient temperature.

Improvement of Gel Strength and Melting Point of Fish Gelatin by Addition of Coenhancers Using Response Surface Methodology

UNLABELLED Fish gelatin is a potential alternative to mammalian gelatin. However, poor gel strength and low melting point limit its applications. The study was aimed at improving these properties by adding coenhancers in the range obtained from response surface methodology (RSM) by using Box-Behnken design. Three different coenhancers, MgSO₄, sucrose, and transglutaminase were used as the independent variables for improving the gel strength and melting point of gelatin extracted from Tiger-toothed croaker (Otolithes ruber). Addition of coenhancers at different combinations resulted gel strength and melting point in the range of 150.5 to 240.5 g and 19.5 to 22.5 °C, respectively. The optimal concentrations of coenhancers for predicted maximum gel strength (242.8 g) obtained by RSM were 0.23 M MgSO₄, 12.60% sucrose (w/v), and 5.92 mg/g transglutaminase and for predicted maximum melting point (22.57 °C), the values were 0.24 M MgSO₄, 10.44% sucrose (w/v), and 5.72 mg/g transglutaminase. By addition of coenhancers at these optimal concentrations in verification experiments, the gel strength and melting point were improved from 170 to 240.89 g and 20.3 to 22.7 °C, respectively. These experimental values agreed well with the predicted values demonstrating the fitness of the models. Results from the present study clearly revealed that the addition of coenhancers at a particular combination can improve the gel strength and melting point of fish gelatin to enhance its range of applications. PRACTICAL APPLICATION There is a growing interest in the use of fish gelatin as an alternative to mammalian gelatin. However, poor gel strength and low melting point of fish gelatin have limited its commercial applications. The gel strength and melting point of fish gelatin can be increased by incorporation of coenhancers such as magnesium sulphate, sucrose, and transglutaminase. Results of this work help to produce the fish gelatin suitable for wide range of applications in the food industry.

Studies on the Biochemical Changes During Fermentation of Salt-Fermented Indian Shad (Tenualosa ilisha)

ABSTRACT ‘Lona ilish,’ a traditional salt-fermented fish product made exclusively from Hilsa (Tenualosa ilisha), is widely consumed in Bangladesh and adjoining northeastern part of India. No detailed scientific studies have been made on ‘lona ilish.’ To understand the science behind this traditional preservation process, the product was prepared in the laboratory following traditional method, and biochemical changes during fermentation period of 150 days were studied at two-week intervals. The protein and protein degradation products as well as lipid and its degradation products were among the important parameters studied. Increase in non-protein nitrogen (NPN), free alpha amino nitrogen (FAN), and total volatile basic nitrogen (TVBN) contents during fermentation indicated hydrolysis of protein. However, the decrease in protein nitrogen content was not significant. A value of NPN/TN of 18% in the fish muscle was found indicative of the ripening point. The loss of lipid in the product was found to be significant. The first rise of peroxide value (PV) immediately after dry salting followed a gradual decrease, and thereafter a second rise was observed in the later half of fermentation period. However, this increase of PV did not impart any rancid taint to the end product. High salt content (15.48%), intermediate moisture content (49.89%) and low pH (5.28) of the final product was found to be satisfactory for stability of the ‘lona ilish’ at ambient temperature.

Involvement of Bacillus licheniformis and Micrococcus kristinae During Ripening of Salt Fermented Indian Shad (Tenualosa ilisha)

ABSTRACT “Lona ilish” is a salt fermented fish product prepared exclusively from fatty Indian shad (Tenualosa ilisha). Despite the presence of salt and metals coming from the container used for fermentation, rancidity is not observed as long as the products are kept immersed in the fermenting brine. To understand the technical principles of this indigenous preservation method, the traditional preparation was followed along with analyses of chemical and microbiological changes. The biochemical and microbiological changes were followed at 15 day intervals during the fermentation period of 150 days. From the 45th day of fermentation onwards, the microbial flora in the product was composed of only two species, tentatively identified as Bacillus licheniformis and Micrococcus kristinae. Because Bacillus licheniformis showed some atypical biochemical reactions, it was tentatively identified as Bacillus licheniformis var. III. These two bacterial species either singly or collectively were involved in the fermentation process.