Effect of feeding habits of fish on the characteristics of collagenolytic proteases isolated from the visceral waste.

In this study, influence of feeding habits of fish on the activity of collagenolytic proteases (CP) has been investigated. CP from the visceral waste of freshwater fish (Pangas, Rohu and Common carp) of different feeding habits was isolated and partially purified by 2-steps, (NH4)2SO4 fractionation and dialysis. Enzymatic activity and purification fold was determined in each step. The molecular mass of the enzymes were close to that of serine collagenases. Enzyme was assayed for temperature and pH optima, effect of sodium chloride and inhibitors. Optimum temperature and pH was 40 °C and 7-8 respectively. Soybean trypsin inhibitor inhibited the enzyme activity, whereas, EDTA exerted no effect, led to confirmation of serine collagenases. CP of carnivore was more active over a wide range of temperature and pH compared to herbivore and omnivore. The study revealed that the feeding habit of fish play decides the optimal physiological conditions for maximum activity of CP.

Quality characteristics of fortified silver carp surimi with soluble dietary fiber: Effect of apple pectin and konjac glucomannan.

The study focused on assessing quality parameters of the surimi incorporated with soluble dietary fibers apple pectin and konjac glucomannan at different levels. The results showed that apple pectin at 0.025% and konjac glucomannan at a 2% level exhibited improved gel-forming ability significantly (p < 0.05). SDS- PAGE revealed high molecular weight protein crosslinks in apple pectin treated surimi gels and disappearance of myosin bands in konjac glucomannan treated surimi gels. The water holding capacity of surimi was the highest when 0.075 g/100 g of apple pectin was added. Konjac glucomannan treated gels exhibited superior whiteness values. The analysis of soluble protein revealed that hydrophobic bonds increased in both the treatments. The hardness values of pectin gels enhanced as the level increased. Other TPA parameters are shown an inconsistent trend. It can be demonstrated that the incorporation of apple pectin and konjac glucomannan at a level of 0.025 and 2.0% may be a novel strategy to improve the gel strength of the surimi.

Isolation, identification and characterization of Staphylococcus sp. from Indian ethnic fermented fish product.

Staphylococci from Sheedal of Northeast India was isolated, identified and characterized. All the isolated staphylococci were found to be coagulase negative. Based on the rpoB gene sequences followed by analysis using NCBI-BLAST software, seven species of Staphylococcus namely, S. piscifermentans, S. condimenti, S. arlettae, S. sciuri, S. warneri, S. nepalensis and S. hominis were recognized. Phylogenetic analyses revealed three major cluster groups. All the seven Staphylococcus showed their NaCl tolerance from 2 to 8%. No species was able to grow at 55°C. Except S. arlettae and S. sciuri, all the isolated staphylococcal species exhibited growth at pH 4-8. No isolated species was able to ferment mannitol, sucrose and arabinose. All the species exhibited moderate to maximum proteolytic and lipolytic activities. All the seven species were found to be sensitive to the antibiotics, namely, erythromycin, norfloxacin, ampicillin, streptomycin and vancomycin, whereas all were resistant to co-trimoxazole. Only S. piscifermentans was found antagonist to Salmonella enterica, Escherichia coli and Bacillus subtilis, although the clear zone was minimal. All the staphylococcal species except S. arlettae and S. sciuri exhibited hydrophobicity ranging from 25 to 66%. The observed characteristics of isolated Staphylococci from Sheedal revealed their role in fish fermentation.