Edible fish powder from Dhoma (Sciaenids spp.)

Edible fish powder of high protein content was prepared from Dhoma (Sciaenids) using different methods. A comparative account of the yield and quality of the products prepared by these methods is presented.

Protein from Jawla prawn (Acetes spp.) and Squilla (Orato squilla nepa)

A simple method of isolation of protein from jawla prawn and squilla, which does not involve any chemical treatment, is reported. The method consists in blending the jawla prawn/squilla with equal quantity of water, removal of chitinous matter, heating the pulp at 112°C for 15-20 minutes and drying the precipitated protein after filtration.

Studies on Thiobacilli spp. isolated from sandy beaches of Kerala

Occurrence, isolation and oxidative activity of Thiobacilli spp. from some sandy beaches of Kerala are reported. These organisms were encountered in polluted beaches and were dominant during monsoon in all the beaches.

Delayed freezing on the quality and shelf-life of Kalawa (Epinephelus spp.)

Kalawa (Epinephelus spp.) caught on board FORV Sagar Sampada was frozen in the absolutely fresh condition as well as after keeping for 5 and 10h at ambient temperature. Evaluation of changes in the quality of these samples during storage at -20°C indicated appreciable difference between the fresh frozen and delayed frozen fish during the initial stages of storage. Fresh frozen and 5h delayed froze fish samples had a shelf-life of more than 62 weeks, whereas the 10h delayed frozen fish had a shelf-life of about 48 weeks.

Application of combined effect of sodium acetate and nisin on reduction of contamination by Listeria monocytogenes in vacuum packaged grass carp (Ctenopharyngodon idella) fillets kept at 4°C

In this study microbiological , chemical quality and fatty acid composition of grass carp (Ctenopharyngodon idella) fillets treated by dipping in sodium acetate (%1 and %3), nisin (% 0.1 and % 0.2) and combination of sodium acetate and nisin was evaluated during 16 days of refrigerated of 4°C Antilisterial effect of nisin was enhanced with the increased concentration of sodium acetate. At day 12 post storage, Listeria monocytogenese count was higher in the control group than the recommended value, however in sodium acetate and nisin treated samples, the count was lower (5.17-5.91 log cfu/g). With increasing the concentrations of sodium acetate, mesophilic counts were lower. Regarding nisin, better results was obtained by applying %0.1 nisin. Greater inhibition of mesophile bacteria was observed when combination treatment was used. The number of lactobacillus was lower when higher concentrations of sodium acetate and nisin were used. Total Volatile Nitrogen values at the end of the experiment were lower in the samples treated with both nisin and sodium acetate and the better results were obtained in combination treatments. Peroxide (PV) at the end of the experiment was 1.9 meq/kg in control, and the lowest values were observed for the treatments 3(%0 sodium acetate +% 0.2 nisin) and 9(%3 sodium acetate +% 0.2 nisin) between 1.08 and 1.62 meq/kg without significant difference. Thiobarbituric acid (TBA) levels at the end of experiment have been shown to be 0.46 mg malonaldehyde per kg in the control. On the other hand treatments 9 had the TBA values of 0.19 mg malonaldehyde per kg which was significantly lower than that of control. Polyunsaturated fatty acids increased by increasing the sodium acetate doses and instead saturated fatty acids and n-6/n-3 ratio decreased. The ratio of UFA/SFA and also C22:6/C16:0 increased when a higher concentration of sodium acetate has been used. The best result obtained by using 3% of sodium acetate but no such relation with nisin was observed.

Development and shelf life evaluation of Tilapia (Orechromis spp.) marinades

Tilapia (Oreochromis spp.) consumption is limited due to its strong muddy odour and the difficulty of processing. In addition, consumption of tilapia is minimal in urban areas because of the low availability. There are no processed market products of tilapia available in Sri Lanka. Therefore, this study was designed to develop a new marinade for tilapia and to evaluate the shelf life of the product. Twelve different treatments of varying amounts of vinegar, salt, chili powder, white pepper and garlic powder were applied to filleted tilapia, and three best treatment combinations were selected using a sensory evaluation test. Processed tilapia was stored in the freezer at -4°C. Treated samples were subjected to evaluation of sensory profile: taste, odour, colour, texture and overall acceptability. Analysis of the shelf life was carried out by using the total plate count, faecal coliform test, acidity and pH at weekly intervals. Results revealed that the third treatment (vinegar 75 ml, salt 5 g, chili powder 5 g, white pepper 5 g and garlic powder 5 g) was best in terms of colour, texture, odour, taste and the overall acceptability according to the estimated medians (6, 6, 6 and 6.33 respectively). There was no significant difference between the first and the third treatment in terms of odour and overall acceptability. There was no significant difference between the three vacuum packed treatments for acidity and pH. Acidity and pH of the three treatments were at an acceptable level, which was below pH 5.3 and above 1.95% acidity. Average bacterial count was 10 colonies and 1.33x10 super(6) colonies respectively in vacuum packed treatments and bottled samples after one week. The acceptable level of bacterial colonies is 1.00x10 super(5). Vacuum packed treatments showed a one month shelf life. In conclusion, marinades can be developed from tilapia with a pleasant taste and acceptable texture.