Removal of fungus and prevention of fungal reinfestation in stored dry salted fish

A simple and effective method is described for converting dry fish products infested with fungus and red halophilic bacteria to acceptable ones. Washing, drying and then smearing with a mixture of 3% sodium propionate in dry, refined salt in a ratio of 1 part mixture: 10 parts dry fish resulted in the fish having a shelf life of 5 months.

Prevention of infestation by Dermestes maculatus Degeer in east African dried fish by solar treatment

East African sun-dried fish infested by Dermestes maculatus were exposed to tropical sunlight at ambient temperature and analysed for insect mortality and weight losses. Solar treatment for 6 to 8 lo was highly effective for one layer of split sun-dried fish and 100% insect mortality was toted, while pest species were still present in the four layer batch. Weight losses between 1.2% and 10.2% were recorded, the top layer suffering the highest loss. The high surface temperature of 60°C caused fish to become brittle and quality losses occurred. A reduction in length of exposure/temperature is probably a presupposition for application of the method to local conditions.

Prevention of infestation by Dermestes maculatus Degeer in east African dried fish using pyrethrum and piperonyl butoxide

East African sun-dried fish dipped for 4 seconds in different solutions of pyrethrum and piperonyl butoxide were analysed for insecticide residue limits. All analyses showed residues above the FAO/WHO MRL; exceeding factors of between 7.6 (22.9 ppm) and 1.6 (5.3 ppm) were found for pyrethrum while exceeding factors between 5.1 (102 ppm) and 1.7 (33.1 ppm) were common for piperonyl butoxide after 6 months storage at ambient temperature. All insecticide treated fish, regardless of dip concentration, were observed to be less susceptible to infestation by Dermestes maculatus than samples of untreated fish. No dry weight losses due to insect infestation were recorded, however moisture evaporation caused weight losses between 6 and 8% during the period. Further investigations showed that careful handling and a dip concentration more in accordance with FAO/WHO MRL than the commercial practice will reduce the cost of insecticides from K.sh. 0.72 to K.sh. 0.23 per kg pyrethrum treated fish.

Indigenous traditional technical knowledge of disease cure and prevention through fish consumption

Our knowledge regarding ethno-medico zoology is scanty and scattered. The present work is an endeavour to collect information on indigenous traditional knowledge (ITK) of disease cure through fish consumption, prepare a consolidated report on this aspect and to document our ITK so that in the long run after due verification (by Medical experts), such ITK can be patented. We also suggest for the recognition of the age old tribal medicine and establishment of a national research institute for tribal medicines at suitable place for the welfare of all the human beings.

Evaluation and comparison of ozone, hydrogen peroxide and physical treatment on fungal infection prevention and hatching rate of Iranian sturgeon (Acipenser persicus)

Ozone due to having low half-life and devoid of environmental harmful effects is recognized as one of the most effective disinfectant and fungicide in aquaculture. The objective of this study is to consider the effects of periodicay ozonation, hydrogen peroxide treatment, and physical treatment capability in hatching rate enhancement. Three concentrations of 0.05, 0.1 and 0.15 ppm ozone (10 min) and peroxide hydrogen with dose of 500 and 1000 ppm in two procedures accompanied with physical treatment and without physical treatment were examined on hatching rate. In the first year, Egg ozonation (0.1 ppm) with physical treatment have been resulted the greatest hatching rate (81.4%). In the second year, egg treatment with 1000 ppm hydrogen peroxide with physical treatment have been showed the greatest hatching rate (78%). Average hatching rate for the blank control treatment (without disinfectin and physical treatment) was 32.7%. From the economic viewpoint, 0.05 ppm ozone with physical treatment, due to considerable minimizing at consumption energy and ozonation system retention costs, indicated as the best treatment than other ozone treatments for fungal control. Very low correlation (r=-0.14) have been observed between hatchery water temperature and fungal infection percentage in control treatment.

Peak identification for PCDD/Fs in environmental samples at different temperature programs

A method has been developed for peak recognition of 136 polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at different temperature programs. Their retention behaviours are predicted on the basis of an identification database of retention values (A, B) of gas chromatography. By the retention times of C-13 labelled 2,3,7,8-substituted PCDD/F internal standards, the retentions of all PCDDs and PCDFs can be calculated. After comparison with the retentions of practical environmental samples, the predicted values have been proved to be very accurate. (C) 2000 Elsevier Science Ltd. All rights reserved.