Efficacy of mint (Mentha arvensis) leaf and citrus (Citrus aurantium) peel extracts in retarding the quality changes in Indian mackerel during chilled storage was investigated. Mint leaf extract showed higher quantity of phenolics and superior in-vitro antioxidant activities than citrus peel extract. Gutted mackerel were given a dip treatment in mint extract (0.5 %, w/v) and citrus extract (1 % w/v), packed in LDPE pouches and stored at 0-2°C. The biochemical quality indices viz. total volatile base nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), free fattyacids (FFA) were significantly (p<0.05) lower in mint extract (ME) treated fishes compared to citrus extract (CE) treated and control fishes (C) without any treatment. Plant extract treatment significantly inhibited lipid oxidation in mackerel as indicated by peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Aerobic plate count (APC) was markedly higher in C group followed by CE group throughout the storage period. As per sensory evaluation, shelf life of Indian mackerel was determined to be 11-13 days for C group, 13-15 days for CE group and 16-17 days for ME group, during storage at 0-2°C.

Pangasianodon hypophthalmus (sutchi catfish) is a fresh water catfish extensively being cultured in the South East Asian countries in the recent years. The present study provides the first report on the effects of gutting on the quality characteristics of aquacultured sutchi catfish stored in ice. pH of whole ungutted and gutted catfish didn't show significant difference (p>0.05) during ice storage period. Total Volatile Base Nitrogen (TVB-N), Alpha Amino Nitrogen (AAN), Free Fatty Acids (FFA) and Thio Barbituric Acid Reactive Substance (TBARS) were lower in gutted fish compared to whole ungutted fish at any particular day during ice storage. However, gutted fish expressed higher rate of primary lipid oxidation than ungutted fish. Textural degradation of the fish muscle as indicated by hardness, cohesiveness, springiness and chewiness was lower in gutted fish. Results of sensory evaluation revealed that gutting has significantly improved the sensory quality of the fish. However, microbiological analysis revealed higher Total Plate Count (TPC) and Enterobactereaceae count in gutted fish. The shelf life of gutted and whole ungutted sutchi cat fish as determined by microbiological analysis was 16-18 days and 18-20 days respectively while storage in ice.

The Striped catfish Pangasianodon hypophthalmus has increasing importance as a candidate for aquaculture in India. It is an abundant and underutilized resource that can be used as a unique protein source to make Fish Protein Hydrolysates. The objective of the present study was to prepare protein hydrolysates from its frame meat using the neutral proteases Papain and Bromelain at 0.5% (w/w) concentration to compare the composition, functional and antioxidative properties. The yield and degree of hydrolysis did not differ significantly between the two proteases. Hydrolysate prepared with papain had a higher crude protein and ash content. They differed significantly in foaming, emulsification and peptide solubility, with papain better in foaming capacity and peptide solubility, and bromelain better in emulsification capacity. Both exhibited almost 90% radical scavenging capacity, and differed significantly in reducing capacity. Thus hydrolysates produced with these proteases vary in their nutritional, functional and antioxidant characteristics.

The effect of vacuum packaging technique on the shelflife of eviscerated pabda catfish (Ompok pabda) during chill storage at 4 ± 2 °C was studied. The shelflife of pabda fish was predicted based on the cumulative observations of biochemical, microbiological and sensory parameters. There was no significant difference in the lipid quality parameters studied between the samples during the chill storage period, whereas, vacuum packaging significantly improved the sensory and microbiological quality. Based on microbiological parameters such as Total Viable Count, Enterobacteriaceae, Escherichia coli, Salmonella Spp, total Vibrios, Listeria monocytogenes, Staphylococcus aureus, faecal Streptococcus and anaerobic sulphite reducers, the shelflife of chilled gutted pabda catfish was estimated to be 14-16 and 18-20 days for air packed and vacuum packed samples, respectively. The sensory parameters showed extended shelflife by four more days for both the samples.

Protein hydrolysates were prepared from defatted engraved catfish roe using alcalase enzyme by a two-stage serial hydrolysis process. The soluble hydrolysate formed after first stage of hydrolysis was removed (RH-1) and fresh enzyme was added at the same concentration to achieve further hydrolysis (RH-2). Further, compositional, surface-active and antioxidant properties of both hydrolysates were compared. The SDS-PAGE profile showed two distinct bands for RH-1, whereas no bands were visible for RH-2. On the other hand, gel filtration chromatography of the hydrolysates indicated 3-4 distinct fractions. Both the hydrolysates showed similar foam forming abilities, however, RH-1 exhibited poor foam stability. Emulsion properties of RH-1 were superior to that of RH-2. The major fractions eluted through gel filtration column were screened for antioxidant properties. Higher DPPH radical scavenging and metal chelating properties were observed for RH-1 second fragment, whereas FRAP and Fe 2+ reducing power was highest for second fragment of RH-2.