In the early stage of fruit rot in satsuma mandarins, there is little change in the appearance of the fruit compared with that of normal fruit, so that it is difficult for an inspector to detect the fruit rot even if using an RGB color camera. Therefore, in order to detect fruit rot, we developed a device that is easily able to measure a spectral image from visible to near infrared. Using the device, the average absorbance of a normal part or a rotted part was calculated from the spectral image, and multiple linear regression (MLR) was performed. From the result of MLR, three wavelengths were selected as variables for the calibration model and used to create an image of each sample by applying the reflectance of the three wavelengths. It was found that the rotted parts of 27 out of 36 samples could be detected using these images.

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In the early stage of fruit rot in satsuma mandarins, rot may be difficult for an inspector to detect. We have developed a system for detecting fruit rot by statistical methods and spectral imaging. Rotting satsuma mandarins were prepared by inoculating rotted pieces of another fruit into test samples. Spectra were measured using the device described in Part 1. We developed a model that can discriminate between rotted and normal parts by multivariate analysis using SIMCA, PLS, and MLR. Before analysis, we tested the pretreated fruits using MSC or 2nd derivative methods. The best results were obtained using a combination of 2nd derivative and PLS methods. Spectral images segmented into 5×5 pixel clusters, calculated using the models and representing only the rotted part, were used to judge whether a fruit was rotted. As a result, we were able to detect sections of rot as small as 1 cm in diameter in validation samples.

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An enzyme-infusion method for controlling the hardness of food materials was applied to white flower beans containing hard tissue. Macerozyme 2A was the most suitable enzyme for softening white flower beans. A process in which the crust surface of the white flower beans was dried before enzyme infusion was effective in softening the beans. In addition, the hardness could be adjusted to 7.5×10⁴N/m² using high-temperature and high-pressure treatment. It was possible to adjust the white flower beans to a desired level of hardness while retaining their shape by concomitant use of the enzyme-infusion method and heat treatment. This technique should be useful for adjusting food materials to a hardness suitable for people who experience difficulty in chewing.

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In order to accelerate the pace of development of environment- friendly cigarette packaging materials, which are intended to replace aluminum foil or polymer film, a method for evaluating the ability of packaging materials to prevent moisture and l-menthol migration was investigated. Firstly, a mathematical model that represents migration of the absorbable components from a pack of cigarettes was developed. The model revealed that three physicochemical properties dominate the migration rates of these components ; they are the gas (vapor) adsorption equilibrium relationship of tobacco, the permeability coefficient of the wrapping material, and the apparent diffusion coefficient through packed cigarettes. These properties were experimentally determined for water and l-menthol, and the validity of the mathematical model was confirmed by comparison of the experimental results obtained using cigarettes with the calculated ones. Finally, the changes in moisture and l-menthol content in a pack of cigarettes during storage were simulated. The results showed that typical paper material cannot be regarded as a barrier to moisture migration ; however, a wax coating significantly improved (lowered) the permeability to l-menthol of paper material, which suggests that wax-coated paper material could possibly become comparable with polymer film for use in cigarette packaging.

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We investigated the effect of the timing of on-tree ethanol treatment and the duration of cold storage on astringency recurrence in ‘Hiratanenashi’ persimmon fruit when the flesh was heated in acid solution. We also compared astringency recurrence in on-tree treated fruit with fruit treated after harvesting with carbon dioxide and ethanol vapor and also with dried and half-dried fruit. In harvested fruit, astringency recurred more readily in fruit that had undergone later on-tree ethanol treatment. Astringency recurred less in fruit stored for longer periods at low temperatures. This tendency was more obvious in fruit treated at the early stage than at the late stage of maturation. Astringency recurred more readily in fruit that had undergone postharvest ethanol treatment than in fruit subjected to on-tree ethanol treatment. The frequency of astringency recurrence in on-tree-treated fruit was almost the same as that of fruit treated postharvest with carbon dioxide. Dried and half-dried fruit showed the least astringency recurrence among the fruits tested in this study.

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As most rice allergens are proteins belonging to the albumin or globulin fraction, it can be expected that soaking uncooked rice in NaCl solution will cause a decrease in the amount of allergens present. Rice grains were soaked in NaCl solutions of different concentrations and temperatures for 24 hours, after which the soluble proteins and total proteins were extracted with 0.5M NaCl and 1% SDS solution, respectively. The proteins, particularly allergens, in each extract were analyzed by SDS-PAGE, immunoblot analysis and ELISA. Allergens of 14-16kDa and 26kDa were removed by dissolution to the greatest extent when the rice grains were soaked in 0.5M NaCl solution at 50°C, with the result that the amount of allergens in the rice grains decreased. The present results provide a useful method for producing hypoallergenic rice.

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Three samples of rice, differing by variety and by place and year of harvest, were pre-washed either once or three times, and then cooked and then kept warm inside a jar rice cooker for up to 24 hours. Taking into account the time of warming that had elapsed, the quality and flavor of the rice were examined. The results showed that depending on the length of warming, rice that had been washed three times tended to show less deterioration in quality, from the point of view of flavor, color tone and smell, than rice that had been washed once. Principal component analysis showed that the dispersion trends of the samples differed according to the number of washes. It was shown that an increase in the number of washes has a consistent effect in maintaining the quality of rice that is kept at a constant temperature.

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The condition of rice maintained at a fixed temperature immediately after cooking was examined in order to assess the effects of different pre-cooking soaking conditions. Measurements of palatability, color b-value (degree of yellowing), and odor discrimination value (SC3) showed a deterioration in quality in rice that had been soaked in hot water over a long period. In particular, it was confirmed that long soaking times tend to cause deterioration in terms of yellowing and odor. Measurement of viable cell counts showed that generally, soaking in hot water over a long period resulted in contamination of the soaking water ; in any case, this was eliminated by cooking.

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[in Japanese]

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