Antioxidant and antimicrobial potential of water lily extracts and their effects on the quality of frozen Nile tilapia (Oreochromis niloticus) fillets.

This study was investigated to evaluate the antioxidant and antimicrobial potential of water lily extracts and their effects on the quality of Nile tilapia (Oreochromis niloticus) fillets during frozen storage (-18 ± 1°C). Antioxidant and antimicrobial activities of water lily extracts, and chemical, microbiological, and sensory qualities of fish fillets were assessed. Results showed that the highest total phenolic content (34.07 mg GAE/g) and total flavonoid content (32.67 mg QE/g extract) were found in the ethanolic extract and the lowest in water extract of water lily. The ethanolic extracts of water lily also exhibited the highest antioxidant capacities and antimicrobial activities than other hydroethanolic and water extracts. The water lily extracts-treated fish fillets showed the highest potentiality in lowering the pH, total volatile basic nitrogen, and thiobarbituric acid reactive substances than the untreated fillets throughout the storage period. Moreover, ethanolic extracts of water lily exhibited comparatively higher efficacy in inhibiting bacterial growth in fish fillets than other extracts-treated fillets. The ethanolic extracts-treated fillets also showed better sensory attributes than hydroethanolic and control fillets. Therefore, ethanolic extract of water lily can be used as a natural preservative in enhancing the quality and prolonging the shelf life of Nile tilapia fillets during frozen storage.

Exploring fish in a new way: A review on non-food industrial applications of fish.

From ancient times fish has always been considered as an important human food item. The purpose of this article is to introduce the perception that beside consumption, fish can also be used as a raw material for the industrial production of different products. In this article such 19 products have been described. Among them, the conventional fish products described herein include isinglass, pituitary gland, chitin, chitosan, pearl essence, fish skin leather, fish protein hydrolysates and concentrates, fish meal and scrap, fish oil, collagen, gelatin, glue, fish silage, pet food and wet feed from fish, fish fertilizer and compost. These products have important applications in aquaculture, agriculture, food, cosmetics and other industries. Different non-conventional hi-tech fish products has been reported such as novel antimicrobial proteins from skin mucus, enzymes, insulin, protamine, blood proteins, salcotonin, antifreeze proteins, hydroxyapatite, burn treatment bandage, albumins, fishbone calcium powder, biochar, biopolymer, bioplastics, fish industry derived rinse water recovery. These products have many significant applications in chemical, biomedical and pharmaceutical industries. Economical, logistic, environmental and technological considerations from fish waste valorization perspectives has also been presented to evaluate feasibility of industrial-scale production of these products.

Dominant phytoplankton groups as the major source of polyunsaturated fatty acids for hilsa (Tenualosa ilisha) in the Meghna estuary Bangladesh.

The tropical estuarine ecosystem is fascinating for studying the dynamics of water quality and phytoplankton diversity due to its frequently changing hydrological conditions. Most importantly, phytoplankton is the main supplier of ω3 polyunsaturated fatty acids (PUFA) in the coastal food web for fish as they could not synthesize PUFA. This study evaluated seasonal variations of water quality parameters in the Meghna River estuary (MRE), explored how phytoplankton diversity changes according to hydro-chemical parameters, and identified the major phytoplankton groups as the main source of PUFA for hilsa fish. Ten water quality indicators including temperature, dissolved oxygen, pH, salinity, dissolved inorganic nitrogen (DIN = nitrate, nitrite, ammonia) and phosphorus, dissolved silica and chlorophyll-a were evaluated. In addition, phytoplankton diversity was assessed in the water and hilsa fish gut. Principal component analysis (PCA) was used to analyze the spatio-temporal changes in the water quality conditions, and the driving factors in the MRE. Four main components were extracted and explained 75.4% variability of water quality parameters. The most relevant driving factors were dissolved oxygen, salinity, temperature, and DIN (nitrate, nitrite and ammonia). These variabilities in physicochemical parameters and dissolved inorganic nutrients caused seasonal variations in two major groups of phytoplankton. Peak abundance of Chlorophyta (green algae) occurred in water in nutrient-rich environments (nitrogen and phosphorus) during the wet (36%) season, while Bacillariophyta (diatoms) were dominant during the dry (32%) season that depleted dissolved silica. Thus, the decrease of green algae and the increase of diatoms in the dry season indicated the potential link to seasonal changes of hydro-chemical parameters. The green algae (53.7%) were the dominant phytoplankton group in the hilsa gut content followed by diatoms (22.6%) and both are contributing as the major source of PUFAs for hilsa fish according to the electivity index as they contain the highest amounts of PUFAs (60 and 28% respectively).