The Tokyo Electric Power Company (TEPCO) Fukushima Daiichi nuclear power plant accident caused by the Great East Japan Earthquake on March 11, 2011, resulted in the release of large amounts of radioactive materials (mainly radioactive iodine ¹³¹I, and radioactive cesium ¹³⁴Cs and ¹³⁷Cs) into the environment that subsequently contaminated agricultural products. Currently, agricultural contamination by radioactive iodine, with a short half-life of 8d, is no longer an issue, since three-and-a-half years have passed since the accident. However, the radioactive cesium isotopes ¹³⁴Cs and ¹³⁷Cs have long half-lives (2 years and 30 years), and have maintained 30% and 92% of their initial radioactivity, respectively. Therefore, long-term monitoring of these radionuclides is required with respect to food contamination. Consumers and food manufacturers alike are greatly concerned with the behavior of radioactive materials during the food processing and cooking of raw agricultural materials. Under a wide range of countermeasures to mitigate the consequences of the nuclear accident for agriculture in the affected regions of Japan, the contamination of agricultural products with radioactive cesium has been greatly reduced in the past three-and-a-half years. Furthermore, numerous studies have focused on examining the behavior of radioactive cesium during the processing and cooking of domestic agricultural, livestock, and fishery products. In this paper, we provide an overview of the inspection results of FY2011 to FY2013 on radioactive cesium levels in agricultural, livestock, and fishery products, as well as research results collected to date on radioactive cesium behavior in the processing and cooking of these products. An English version of all figures and tables in this paper is presented in the Appendix.

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The proximate composition (%) of Japanese walnut (Shinano) was determined to be as follows : crude protein, 13.6; crude fat, 67.5; carbohydrate, 14.3; ash, 1.7; and moisture, 2.9. 1-1-diphenyl-2-picrylhydrazyl radical scavenging activity was 186.2 and 144.8μmol of Trolox equivalent per gram dry weight in Japanese and American walnuts, respectively, indicating that Japanese walnuts exhibit slightly stronger antioxidant capacity than American walnuts. The total polyphenol content was 2 202.3 and 1 855.0mg of gallic acid equivalent per 100g dry weight in Japanese and American walnuts, respectively, indicating that Japanese walnuts have a slightly higher polyphenol content than American walnuts. The principal ellagitannin compounds were 445.7 and 473.5mg of ellagic acid equivalent 100 gram dry weight in Japanese and American walnuts, respectively, indicating that American walnuts have slightly higher ellagitannin content than Japanese walnuts. The results presented above indicate that polyphenolic compounds contribute to the antioxidant capacity. The data also suggest that the antioxidants in walnuts include both identified ellagitannins and unidentified polyphenolic compounds. The study also demonstrates differences in polyphenolic composition between Japanese and American walnuts, which reflect antioxidant capacity. These observations are likely related to differences between the two countries in cultivation region and horticultural practices, as well as genetic factors and post-harvest processing.

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The endosperm enzyme activity of rice is thought to vary depending on various parameters such as cultivar type, storage conditions, and cultivation region. Focusing on the variation in enzyme activity, we examined the relationship between these parameters and the palatability of cooked rice. To improve measurement convenience, rapidity, substrate specificity and sensitivity, enzyme activity was assessed using synthetic substrates. The following enzymes were examined and subjected to chemometric analysis : α- and β-amylases; α-glucosidase; β-glucanase; β-galactosidase; α-mannosidase; and β-xylanase. The results indicated that the endosperm enzyme activities differed among cultivars closely related to Koshihikari, namely, activities of α- and β-amylase and β-galactosidase differed significantly between cultivars. “Pirouette” multivariate analysis software was used to perform principal component analysis and thereby group cultivars according to endosperm enzyme activity. Haenuki was grouped closely to Koshihikari, whereas Kirara 397 was distantly related to Koshihikari. We were able to correlate carbohydrate-related enzyme activity with the characteristics of the cultivars.

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In order to gain insight into information expected by consumers purchasing Japanese tea products, the need for information related to preference, and methods for providing such information, an online survey of consumers in Japan was performed. The questionnaire results disclosed that consumers regarded quality as the most important factor in purchasing leaf-type tea as a whole, although price was considered a point of focus depending on gender and age. Indication of tea quality information was expected on packages, such as sensory information including tastes or flavors. Survey answers about quality information displayed on bottled green tea drinks were similar to the results for leaf-type tea. Indicating sensory information appeared to be effective for consumers at tea shops, department stores, and mail-order services for buying tea products, because such consumers had much interest in quality information and high expectations for its indication. On the other hand, supermarket users had a propensity for a lower interest in tea and its quality compared to the users of tea shops, department stores, and mail-order services. Therefore, arousing interest in Japanese teas through education might be needed to enhance the effect of quality indication in supermarkets. Because understandability of the indication methods depends on the focus of the consumer’s interest, it is difficult to satisfy the requests of all people by a single indication mode. However, if a target consumer group is specified, further benefits of quality indication can be obtained by suiting the indication mode to the majority of consumers.

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The effect of low-temperature storage on the sugar content of table potato cultivars was investigated. Cultivar-specific differences in sugar content during storage were observed. Specifically, the potato varieties “Inca-no-mezame” and “Inca-no-hitomi” showed a remarkable increase in sugar content with long-term storage at low temperature. In “Inca-no-mezame”, tubers harvested from two different fields showed similar total sugar content after one-month storage under identical storage conditions. Altering the storage temperature from 2°C to room temperature decreased sugar content by 40% and 50-70% at one week and one month, respectively. Following one week of storage at room temperature, sugar content was restored to 80% of the original value by storage at 4°C for 3 weeks.

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We investigated the dynamics of radioactive cesium (¹³⁴Cs plus¹³⁷Cs) during preparation and cooking of dried Japanese udon noodles (dried noodles). Dried noodles are prepared by drying treatment of fresh noodles. The radioactive cesium in the dried noodles, boiled noodles, broth and rinse water were measured with a germanium semiconductor detector. Processing factor (Pf, ratio of radioactive cesium concentration in processed materials to raw materials) and food processing retention factor (Fr, ratio of residual radioactive cesium content in processed materials to raw materials) were calculated. Concentrations of radioactive cesium did not show significant differences (p<0.05) between flour and dried noodles. The Pf values for thick noodles (1.8mm×3mm) and thin noodles (1.1mm in diameter) were 0.935 and 0.977, respectively. On the other hand, the Pf values for boiled thick noodles and boiled thin noodles were 0.063 and 0.038, respectively. Greater than 80% of the radioactive cesium contained in the raw noodles was removed from the thick noodles and thin noodles during boiling for 15 min and 3 min, respectively. The drying treatment during noodle preparation of dried noodles may have no effect on the removal of radioactive cesium by cooking, because these removal percentages corresponded well with those of fresh noodles reported in our previous study. An increase in boiling water volume contributed to a significant decrease (p<0.05) of radioactive cesium concentration, although both pH and hardness of water had no significant effects (p>0.05) on the dynamics of radioactive cesium during cooking.

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