[en] The importance and need of universal uniform methods of measuring and reporting absorbed doses as related to the interpretation of irradiation effects on food items are discussed. The need and importance for uniformity of dose in the interpretation of microbiological and organoleptic studies of fishery products are specifically discussed using limited actual data as well as an illustrative example. (author)

[en] Hake fillets packed in plastic bags, permeable and impermeable to gas, in a normal atmosphere and under vacuum were irradiated at 100, 150 and 200 krads with subsequent storage at refrigeration temperatures (1°C). Periodic biochemical checks were carried out on the level of decomposition and sensory assessments made on the quality of raw and of cooked fillets, using untrained tasting panels consisting of 20 and 10 judges respectively. The results are discussed and the conclusions given. (author)

[en] A survey project on the irradiation preservation of seafoods, sponsored by the Government of Iceland, the International Atomic Energy Agency and the United States Atomic Energy Commission has been carried out at the Icelandic Fisheries Laboratories. A summary of results obtained on Norway lobster tails, deep-sea shrimp and cod fish is given in this paper. (author)

[en] Following the many successful experiments substantiating the feasibility of preserving fishery products with gamma rays, there remains the task of obtaining approval from the U.S. Food and Drug Administration, before the process can be used in commerce. The Gloucester Technological Laboratory has conducted research in two pertinent areas: in one study an empirical test has been used to collect data in one aspect of a multi-laboratory investigation of a possible botulism hazard in radiation-pasteurized fishery products; in the second study the efficacy of the process was substantiated under commercial shipping conditions. (author)

[en] The author describes a series of experiments on the irradiation of fresh white (lean) fish of the species Merluccius merluccius, in which the dose applied ranged between 50 and 300 krad and the irradiation conditions, i.e. packaging in different materials, temperature and atmosphere, were varied. The microbiological studies were concentrated on the evolution of residual microbial flora as a function of the parameters considered. The results obtained are discussed with a view to evaluating their significance from the commercial and health standpoints. It is concluded that under suitable conditions, with storage temperatures from 0 to 3°C and low initial contamination levels, it is possible to secure a commercially worthwhile prolongation of the storage life of hake fillets amounting to 10 to 12 days, by the application of doses of 50 and 100 krad. Larger doses are required for higher initial contamination indices-and also whenever gas-permeable wrapping materials are used. It will be necessary, however, to make, further tests to confirm the conclusions, and in so doing to broaden and improve various aspects and areas of the scheduled research. (author)

[en] Proposals to treat packaged fish with pasteurizing doses of radiation, and the potential health hazards of this process are described. It is proposed to introduce irradiation into an existing processing and distribution chain for retail packs of chilled fish. The Codes of Practice at present in use provide an adequate safeguard against possible health hazards, primarily by the control of temperature, and limit the storage time to about half the potential shelf life of the fish. Irradiation of these products with 0.3 Mrad will result in a considerable extension of storage life whilst maintaining the same high quality of the product. It is concluded that whilst Clostridium botulinum types E, F and non-proteolytic B could be present in the raw material, no particular health hazard exists unless gross malpractice occurs, especially in relation to the temperature of storage. (author)

[en] The effect of age of fish prior to irradiation (100 krad) on the post-irradiation storage life and bacterial flora of aerobically stored haddock fillets has been investigated. Significant extensions in storage life were found after irradiation, even for fish judged to be of fairly low quality initially. However, fillets from older (low quality) fish were found to be borderline in quality for most of their extended storage life, while fillets from .fresh fish were borderline in quality only during the latter half of their extended storage life. Although bacterial numbers were initially lower on irradiated fish, 2-day and 5-day irradiated fish had 10-100 times as many bacteria as their unirradiated counterparts at spoilage. Initial quality did not appear to affect, qualitatively, the flora developing during storage on unirradiated fillets on which pseudomonads and Achromobacter predominated. However, on irradiated fillets, while Achromobacter predominated, a change in the character of the Achromobacter isolates from 2-day and 5-day irradiated fish, was observed at spoilage. (author)

[en] Fresh gwyniad trout and carp were vacuum-packed in plastic foil impermeable to gas and water vapour, irradiated with 10-MeV electrons, and stored under melting ice. Sensory, chemical and microbiological tests were then carried out over a period of four to two weeks. In the case of gwyniad, best results were obtained with a dose of 0.1 Mrad which prolonged Grade-1 quality shelf life from nine to 23 days. With trout a dose of 0.05 Mrad improved the shelf life from 15 to 21 days. Doses higher than 0.1 Mrad for gwyniad and 0.05 Mrad for trout caused a noticeable loss of flavour. In this respect trout appears to be particularly radiation-sensitive in comparison with other species of fish. In contrast, carp turned out to be particularly well suited for radiation-preservation treatments, as its flavour is not negatively affected even by relatively high radiation doses. While unirradiated carp could be stored for 15 days', a dose of 0.5 Mrad preserved the Grade-1 quality shelf life for 35 days. Higher doses, up to 1.5 Mrad, caused a further reduction of microbial counts without improving the shelf life beyond the results obtained with 0.5 Mrad. The latter dose, which does not affect flavour, can therefore be considered optimal for carp. (author)

[en] The increasing emphasis on the need for protein-rich foods to improve the nutritional status of the world’s population has stimulated research on new methods of preserving fishery products. The sea offers a source of protein that could markedly reduce the protein gap existing in many parts of the world. The major problem in attaining a more complete exploitation of these products is how to preserve them so that they can be transported from the points of origin to areas of greatest need. The use of ionizing radiation as a preservation method has been satisfactorily demonstrated in many countries. In some respects it offers advantages over conventional methods; for example, it prolongs the market life without using heat or chemicals, and what is more, the products are treated while they are sealed in commercial types of containers. Although radiation processing appears feasible, additional research is needed to improve certain quality attributes of some treated foods and to demonstrate to the satisfaction of health authorities' that no deleterious effects result. To obtain advice on the problems that need attention a Panel on Irradiation Preservation of Foods of Marine Origin was convened in Vienna, by the Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture, on 15—19 December 1969. The main purpose of the panel’s work was to advise the Director General of the Food and Agriculture Organization of the United Nations and the Director General of the International Atomic Energy Agency on how these organizations can best fulfil their roles in radiation research on fishery products. The meeting was attended by thirteen experts from various countries and one representative of the World Health Organization. Reports were presented on research performed and detailed discussions were held on work done in perfecting the radurization treatment of fishery products. Evaluations were made of the microbiology of the radurization process, with special reference to the control of Clostridium botulinum. type E, in irradiated products. Recommendations were made on the research needed to solve specific problems and to obtain the information necessary for a full understanding of the mechanisms involved in certain biological systems that bring about the spoilage and deterioration that decreases the market life and usefulness of fishery products. The proceedings contain the contributions of the members of the panel with the general conclusions and recommendations for further research

[en] Radiation-processing procedures have been developed for extending storage shelf life at sub-room as well as room temperatures for Bombay duck (Harpodon nehereus). shrimps (Metapenaeus sp. and Parapeneopsis stylifera) and white pomfrets ( Stromateus cinereus). The physical, chemical and microbiological changes in each of these seafoods have been evaluated critically to establish the technological merits of the processes. Studies on the radiation sensitivity and biochemical properties of fish microflora provide evidence for the selective control of rapid spoilers in irradiated Bombay duck. The biochemically inert nature of Micrococcus sp. predominant in radiation-pasteurized Bombay duck concurrent with the suppression of Gram-negative spoilers, brings about a high acceptability of irradiated products during storage. Irradiation at 0.1 Mrad extends the storage life of Bombay duck for 18—20 days at 0—2°C due to a lower spoilage rate as against the rapid deterioration of unirradiated samples within 5—7 days. Textural losses due to exudation of drip in irradiated as well as in unirradiated Bombay duck can be minimized by pre-dip treatments in 10% NaCl for 60 min or in 10% sodium tripolyphosphate for 15 minutes. Fresh Bombay-duck fillets or laminates can be preserved by a radiation dose of 0.25 Mrad for three weeks at 0—2°C and partially dried laminates for three months at 28—32°C. Insect damage to air-dried or commercially sun-dried Bombay-duck laminates can be prevented by 15 krads. The tolerance dose in the range 0.15—0.25 Mrad for shrimps has been selected on the basis of retaining the naturally occurring pigment and the absence of irradiation odours. The radiation-pasteurization process for fresh and blanched shrimps (100°C, 4 min) extends the shelf life by 18 and 130 days respectively at 0—2°C. Cooked and semi-dried shrimps can be stabilized for room-temperature storage for 3 and 6 months respectively. The development of rancid odours and yellow discolouration during the storage of irradiated pomfret (above 0.3 Mrad) can be effectively minimized by maintaining anaerobic conditions during irradiation and storage. The radiation- pasteurization process for white pomfret fillets consists of anaerobic packaging and irradiation (0.1 Mrad). This treatment augments the shelf life of pomfrets by 35 days at 0—2°C as against the spoilage of unirradiated products within 7 days. Transportation studies of irradiated Bombay duck, eel and shrimps show prospects for radiation-pasteurization processing in the inland distribution of fishery products. (author)