Takeo Shiina

Effects of cultivation, transportation and distribution methods on the life cycle inventory (LCI) of fresh tomato

Life cycle of fresh tomato was evaluated to determine CO2 emission throughout the cultivation and distribution processes. Low temperature (LT) and modified atmosphere packaging (MAP) have been compared considering the quality aspect. Road and marine transportation were also compared. This study revealed that the method of cultivation, transportation and distribution systems affect the overall life cycle inventory (CO2 emission). The distance between production and consumption area affected the LCI significantly. MAP method would not be environmentally acceptable over the LT in the case of road transport if the distance is less than 2500 km even though no cooling treatment is required during transportation and storage. However, MAP method would be better option than the LT distribution in case of marine transport if the distance is more than 1000 km. The distance of acceptability of MAP method differs because of the traveling speed of road and marine transportation. Therefore, a change in cultivation (greenhouse to plastic-cover), transportation (road to marine) and distribution processes (LT to MAP) is required to minimize the LCI.

Effect of Processing Condition on the Energy Consumption and Quality of Rice

Rice processing processes were studied to determine the effect of processing conditions on energy consumption and qualities of rice. Two types of rice (Short grain: Japonica; long grain: Indica) were used for this study. The brown rice was milled to different milling degree and the energy consumption and qualities of rice were measured. Hydration rate and cooking processes were also studied. Short grain required more energy than the long grain for a certain degree of milling. The energy consumption and whiteness (lightness) value of rice increased with the increase of milling degree. However, the head rice (whole kernels) yield and food nutrients (dietary fiber, protein and vitamins) decreased with the increase of milling degree. There was no significant difference in water absorption rate and cooking energy among the partially and well milled rice (2% to 10% milling degree), however brown rice required more energy than the partially or well milled rice. It is worthwhile to note that overall energy consumption was greater for long grain compared to that of short grain. This study reveals that lower milling degree not only conserve milling energy, but also retain more food nutrients in rice. However, taste of rice and its acceptability need to be considered to adopt lower degree of milling.

Design Method of Power Spectrum Density Profile for Random Vibration Test Based upon S-N Curve

The susceptibility of the product against the vibration was studied at an actual transport condition to develop a random vibration test method. The validity of obtaining power spectrum density (PSD) and its design method were investigated by using a low cost three dimensional vibration data logger (interval recording type). The logger was subjected to the sinusoidal vibration in vertical direction. PSD data obtained by the data logger (equipped with software) gave a lesser level of power in the low frequency range provably due to the limitation of the resolution of frequency. Therefore, attention should be paid not only on the upper limit of the frequency based upon sampling theory but also on the lower limit to evaluate PSD by digital Fast Fourier Transformation. A simple average of the PSD data will give a too little power level, whereas selection of the highest level PSD give an over power level to obtain PSD for the simulated transport test. However, it is possible to obtain a PSD data considering the damage susceptibility of the product by using the S-N curve. Moreover, an accelerated test, shortening of time for the vibration test than the actual transport is possible by using the S-N curve.

Analysis of Equilibrium moisture content and L-ascorbic acid during hot air drying for sweet potato

The drying characteristics and L-ascorbic acid changes of sweet potato samples were investigated during hot air drying at four temperatures ranging from 30 to 60 °C. Equilibrium moisture contents (EMC) of sweet potato samples in the desorption process were measured at various temperatures by a static method. The measured results were fitted to the Chen-Clayton equation. Using both the measured moisture content data in the drying test and the EMC values, the drying process was evaluated with a combination of both the exponential drying model and an infinite plane sheet model for the diffusion equation. The diffusion coefficient was calculated using an infinite plane sheet model. An Arrhenius-type equation was used to estimate the diffusion coefficient of sweet potato in response to temperature, and the activation energy of sweet potato during hot air drying was estimated. In order to examine the nutrient changes in sweet potato during hot air drying, a first-order reaction rate equation was applied to changes in the decomposition of L-ascorbic acid contents during hot air drying. An Arrhenius-type equation was also applied to estimate the decomposition rate coefficient k’. Accordingly, the activation energy needed for decomposition during hot air drying of sweet potato was estimated to be 48.8 kJ·mol-1.

Effect of Cooking Mode on the Cooking Behavior of Rice

The cooking process was studied with an automatic rice cooker to determine the effect of cooking mode on the properties of cooked rice. Each form of rice was cooked with three different water-rice ratios in their corresponding cooking mode. The hydration characteristics, temperature and energy consumption profile were also measured. The hydration increased with an increase in soaking time and was higher for milled rice compared to the brown rice. Cooking time, temperature and energy consumption profiles varied from rice to rice, and seems to be dependent on the cooking mode, and consumed different amount of energy. For a certain hardness value of cooked rice, brown rice required the longest cooking time and water-rice ratio and attains highest amount of moisture compared to others, hence consumed the highest amount of energy. This study also revealed that the cooking properties of rice dependent on the forms of rice, water-rice ratio and the preset cooking mode.