Amjad K. Balange

Compensatory Growth and Changes in Nutrient Composition in Post-Larvae of Giant Prawn, Macrobrachium rosenbergii, Following Starvation

ABSTRACT The effect of a period of starvation and subsequent re-feeding on the weight and length gain of post-larvae of giant prawn, Macrobrachium rosenbergii, was studied during an eight-week investigation. Post-larvae of Macrobrachium rosenbergii weighing 5.15±2 mg were grown in aquaria at water temperature of 28±1°C. Post-larvae of the control treatment were fed to satiation during the experimental period while post-larvae in other three treatment groups were deprived of diet for 1, 2, and 4 weeks, respectively, and were subsequently fed to satiation during the realimentation period up to 8 weeks. Post-larvae deprived of diet for 1 and 2 weeks, compensated for lack of diet by weight gains of 1,842% and 1,813%, and better feed conversion efficiency (0.53% and 0.34%), respectively. Post-larvae deprived of diet for 4 weeks showed significantly (P < 0.05) lower gain in body weight (811%) than that of the control group (1,609%), but showed significantly higher specific growth rate (7.99±0.06) than other treatments during realimentation period. Data reported indicate that post-larvae of M. rosenbergii are able to achieve complete growth compensation within two weeks following feed deprivation of two weeks.

Development of functional extruded snacks by utilizing paste shrimp (Acetes spp.): process optimization and quality evaluation

BACKGROUND Functional extruded snacks were prepared using paste shrimp powder (Acetes spp.), which is rich in protein. The process variables required for the preparation of extruded snacks was optimized using response surface methodology. Extrusion temperature (130-144 °C), level of Acetes powder (100-200 g kg-1 ) and feed moisture (140-200 g kg-1 ) were selected as design variables, and expansion ratio, porosity, hardness, crispness and thiobarbituric acid reactive substance value were taken as the response variables. RESULTS Extrusion temperature significantly influenced all the response variables, while Acetes inclusion influenced all variables except porosity. Feed moisture content showed a significant quadratic effect on all responses and an interactive effect on expansion ratio and hardness. Shrimp powder incorporation increased the protein and mineral content of the final product. The extruded snack made with the combination of extrusion temperature 144.59 °C, feed moisture 178.5 g kg-1 and Acetes inclusion level 146.7 g kg-1 was found to be the best one based on sensory evaluation. CONCLUSION The study suggests that use of Acetes species for the development of extruded snacks will serve as a means of utilization of Acetes as well as being a rich source of proteins for human consumption, which would otherwise remain unexploited as a by-catch.

Physicochemical and Gel Properties of Myofibrillar Protein from Sin Croaker (Johnius dussumieri) Fish During Ice Storage

ABSTRACT The physicochemical and gel properties of myofibrillar protein (MFP) from sin croaker fish were studied during ice storage for 18 days. Significant changes in the trends of solubility, Ca2+ ATPase enzyme activity, surface hydrophobicity, and water holding capacity of extracted MFP were observed by the 6th day of storage. The Ca2+ ATPase enzyme activity reduced significantly (p < 0.05) by the 6th day of storage. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) did not show a remarkable change in the concentration of myosin heavy chain. Surface hydrophobicity increased almost four times from its original value of 18.98 µg; whereas, water holding capacity showed a fluctuating trend during storage. The emulsion capacity of the MFP was in the range of 0.89- to 1.92-mL oil/mg protein during storage. The gel strength value (313.45 g.cm) of heat-induced gel prepared from fresh minced meat decreased significantly (p < 0.05) by the 6th day of ice storage. Texture profile analysis revealed that changes in hardness and gumminess were concurrent to steeply reducing breaking force up to the 6th day. The histological observation showed gradually increasing gaps between muscle fibers. The histological observations and physicochemical quality indicated that the sin croaker fish can be used for producing good quality surimi when stored for up to 6 days in ice.

Functionality of chitosan in batter formulations for coating of fish sticks: Effect on physicochemical quality

Chitosan is a natural polymer having diverse applications in food industry. The present study was undertaken to evaluate chitosan as a hydrocolloid in batter composition in developing enrobed fish sticks with better functional properties and improved quality. Different concentrations of chitosan gel were made in acetic acid medium and incorporated into batter for making enrobed fish sticks. Coating parameters, fat uptake, oil reduction, chemical quality parameters, instrumental texture analysis and colour were studied. Addition of chitosan gel had a significant effect (P<0.05) on the coating pickup, adhesion degree and cooking yield of the product. Total volatile basic nitrogen, pH, lipid oxidation parameters like peroxide value and thiobarbituric acid reactive substances of par-fried fish sticks also showed significant differences. The oil reduction in par-fried samples were 36.84, 65.05, 73.83, 77.65% respectively for 0.5, 1.0, 1.5, 2.0% chitosan added samples. Addition of chitosan significantly reduced crispness, gumminess, Warner-Bratzler shear force and toughness (P<0.05) of the product. The study clearly demonstrated that the inclusion of chitosan at 1.0% in batter can improve functional and other quality aspects of enrobed products.

Quality Characteristics of Tilapia Surimi: Effect of Single Washing Cycle and Different Washing Media

ABSTRACT Surimi was prepared by washing with single washing cycle with cold water (T-1), alkaline saline (0.2% NaHCO3 and 0.15% NaCl; T-2) solution, and with calcium chloride and salt (0.2% CaCl2 and 0.1% NaCl; T-3), respectively, and compared with conventional washed (CW) surimi. T-2 exhibited significantly (p ≤ 0.05) increased moisture content, which correlated with increased yield, pH and also significantly decreased lipid and ash content. A significant (p ≤ 0.05) decrease in expressible moisture content was also observed in T-2, which suggested higher water holding capacity compared to other treatments. Heat-induced surimi gels exhibited highest L* (p ≤ 0.05), followed by surimi in all the treatments. In the case of L*, T-1 showed highest lightness, followed by T-2, which was comparable to CW. The lowest myoglobin content was exhibited by CW surimi (p ≤ 0.05), which is due to repeated washings. T-2 gel showed higher elasticity, texture, and overall acceptability than others (p ≤ 0.05), except for the whiteness. In all the aspects, T-2 was comparable with CW. Washing with one cycle of T-2 solution can not only improve the quality of surimi but can reduce the wastage of water that is released into the environment without further treatment.

Effect of Heat Treatment at Different Stages of Rigor on the Quality of Pacific White Shrimp (Litopenaeus vannamei)

ABSTRACT Effect of blanching and cooking on the quality of Pacific white shrimp with skeletal muscle severed (by beheading and peeling) at different stages of rigor was evaluated. Peeling and beheading shrimp in post-rigor stage resulted in higher yields compared to shrimp in in-rigor and pre-rigor stages. Weight loss due to blanching/cooking was highest when skeletal muscle was severed in in-rigor stage followed by post- and pre-rigor stages. Highest crude and sarcoplasmic protein contents were found in the shrimp blanched or cooked while in in-rigor stage followed by pre-rigor and post-rigor stages. Hardness, springiness, and chewiness were found to be better in the shrimp blanched in pre-rigor stage. Highest sensory scores for color, appearance, succulence, and odor were found for shrimp blanched or cooked in pre-rigor followed by in-rigor stage. Instrumental analysis of color and texture confirmed the sensory scores.