[en] Polysaccharides widely used in the food industry were studied in terms of sterilization of bacteria by irradiation. 12 items of polysaccharides irradiated by electron beam ware investigated for bacteria count and the functional property of pH, gel strength, bloom and viscosity. This study aims to determine the sterilization effect by absorption dose and the applicability of the electron beam irradiation toward polysaccharides. Results shows that 1) Over 5kGy absorption dose are enough to be able to sterilize bacteria in the polysaccharide themselves. 2) We reconfirm that Arabic gum will be applicable for the electron beam irradiation, which has been used in some foreign countries. 3) Electron beam irradiation will be useful for Gellan gum b (acetyl type), as gelling agents in the food application. (author)

[en] Decomposition of fatty acid hydroperoxide is found to be proportional to the radiation dose. A dose of 20 kGy was found to decompose the hydroperoxide by 98%. Addition of phenolic antioxidants at 4.5 mM could not prevent the decomposition at 20 kGy but the phenolic antioxidants at 20 mM prevented the decomposition. (author)

[en] The dried petals of Safflower (Carthamus tinctorius L.) that the raw material for preparation of food coloring agent, Carthamus yellow pigment, were irradiated with the doses of 5, 10 and 30 kGy of gamma ray and electron beam. Then, the effects on the extraction efficiency and the composition of pigments were examined. (1) It was confirmed that the efficiency of pigment extraction was increased by the irradiation of ionizing radiation to the sample. With gamma ray irradiation at 5 kGy and 10 kGy, the extraction efficiency increased 10% and 15% respectively, however, with irradiation dose at 30 kGy, the extraction efficiency decreased 5% more than non-irradiated sample. With electron beam irradiation at 5 kGy and 10 kGy, extraction efficiency increased 4% and 9% respectively, however, the increase were minimal at 30 kGy. (2) The absorption spectra of the solution extracted from the irradiated and non-irradiated samples were nearly identical and demonstrated that a change in the composition of pigments did not occur with irradiation. However, the chromophore in pigment molecules may be decomposed with high doses of irradiation, such as 30 kGy, it can be assumed that such irradiation can cause a decrease in extraction efficiency of pigments. (3) It was confirmed that decontamination of microorganisms was practicable, with irradiation of ionizing radiation at more than 5 kGy. (author)

[en] For the practical use of radicidation, we studied on the effects of γ-ray and electron beam on functional properties of beet red colorant, natural colors with low heat stability and high possibility of microbe contamination. Neither γ-ray or electron beam had any significant influence on color contents and color tone of red beet products at less than 10 kGy of irradiation for the practical use. Influence of moisture content at level of less than 20% in powdered product was not observed. The results suggest that both γ-ray and electron beam irradiation is significantly effective in decontamination of powdered beet red products. (author)

[en] Irradiated fresh meat or fishery products have been expected to store and distribute under refrigerated temperature below 10degC. From previous reports, growth of coliform bacteria in these products were suppressed by gamma-irradiation below expected doses obtained at 30-37degC. This research was performed to observe the irradiation effect on the inactivation of Escherichia coli and related bacteria at different incubation temperatures of 10-40degC on plate agar after irradiation. From this study, D10 values of all strains decreased 17- 45% at 10degC compared with maximum D10 values at 30- 40degC. Radiation sensitivities were related to the ability to grow at low temperatures in which psychrotrophic type E. coli A4-1 indicated most sensitive to radiation, next of Salmonella enteritidis YK-2, E. coli S2, B4 whereas most resistant at Enterobacter agglomerans K3-1. (author)

[en] Threshhold dose for organoleptic changes by gamma irradiation in shell eggs is at 0.5 kGy, whereas frozen egg products is at 2.4 kGy and dehydrated egg products is at 3 kGy respectively. For the elimination of Salmonella, necessary dose is estimated to be 1 kGy for shell eggs and to be 2 kGy for dehydrated egg products from survival fraction of S. Typhimurium or S. Enteritidis. Contamination of Salmonella occur significantly in liquid egg products and for the reason of threshhold dose of organoleptic changes, irradiation treatment should be applied to dehydrated condition with 2-3 kGy. (author)

[en] In order to the practical use of radicidation of beet red, natural food colorant with low heat stability and high possibility of microbe contamination, we studied on the energy dependency and dose rate effect for the influence on functional properties of the beet red colorant. For the elucidation of energy dependency, the γ-ray (1.33 MeV) and electron beams with different accelerating voltages (0.75, 1, 2.5, 5 and 10 MeV) were used. The dose rate effect was studied under the different dose rate by using γ-ray (0.723, 1.91 and 4.55 kGy/h) and electron beams with accelerating voltage of 10 MeV (1.0 x 10³, 2.6 x 10³, 7.0 x 10³, 7.0 x 10³, 2.0 x 10⁴ and 5.0 x 10⁴ kGy/h). The results obtained in this study showed that regardless of these energy and dose rate, the functional properties of the beet red colorant were little affected by irradiation less than 25 kGy of ionizing radiations. (author)

[en] Changes in functional properties of pectin extracted from sugar beet or citrus peel by electron beam in solid state or aqueous solution were investigated. Citrus pectin (CP) was degraded at both solid state and aqueous solution by irradiation with electron beam. Sugar beet pectin (SBP) was degraded at solid state but in aqueous solution at high concentrate was polymerized by irradiation with electron beam. SBP polymerized by electron beam formed hydrogel. This hydrophilic polymer was useful as water absorbent. Moreover, it was confirmed that the emulsification stability and acidified milk beverage stabilization of SBP was enhanced by electron beam. (author)

[en] Penetration range and depth-dose distribution of 10 MeV electrons within commercial packages of experimental animal feeds were examined with a high power electron accelerator for verification of the application of high energy electron beam irradiation to sterilize experimental animal feeds. Optimum packaging sizes were proposed based on the experimental results. The change of the vitamins and the efficacy of the sterilization by the irradiation were also studied. It is confirmed that the sterilization of experimental animal feeds by 10 MeV electron beam has been completely practical. (author)

[en] Thaumatin, egg white and soybean protein were selected as samples of proteinous food additives, and changes in the intensity of signals appearing in them after they had been irradiated with electron beams were measured by ESR. It was found by such measurement that the positions of signals of thaumatin and soy proteins are nearly the same. Changes in the intensity of radicals in thaumatin calculated on the basis of the coefficients of the respective approximations obtained by using thaumatin which had been irradiated and then stored at 4degC, 25degC, 37degC and 60degC showed that there is a temperature range to determine the remaining of such radicals (inner: 19.7degC, outer: 15.23degC) and that such radicals tend to decrease straight line-wise. It was confirmed that the intensity of signals in the protein powder such thaumatin and soy protein would not be affected at the storage condition below 15degC. (author)