Abstracts of the Annual Meeting of the Japan Society of Cookery Science

This research aims to clarify the meaning of cooking in human life. Most male usually don’t cook in daily life. However some males start to cook after retiring their jobs. This research focuses on the male elderly group in which twenty members learn how to cook together once a month. The data was collected from the observation and interview ( April2014~May2015). This research examines about (1) The behavior of male elderly in cooking classes, (2)Cooking experience in their daily life, (3)Changes before and after their cooking learning (4)Relations between their cooking and their former jobs. This research shows the following results; All members talked with others very much in cooking and eating. They talked about foods, the way of cooking, and their own experience on cooking. They discussed about social problems and their healthy condition during eating. Cooking is so important tool for them to make relationships with others.

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Although partially abraded brown rice was not familiar, the eating behavior was similar to that of habitually eaten cooked rice. Cooked partially abraded brown rice would be acceptable for Japanese consumers as a healthy staple food.

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[Object] Ca²⁺-ATPase activity of myofibrillar protein as an indicator of denaturation has already been reported. But the relationship between the thermal denaturation degree determined by food technology method and chemical changes of the protein has not yet been elucidated. In this study, we examined the correlation between
the protein denaturation degree and Ca²⁺-ATPase activity or protein solubility during the heating.
[Method] Thermal denaturation parameters of protein of kuruma prawn (Marsupenaeus japonicus) were measured by differential scanning calorimetry (DSC). Then denaturation distribution of protein in prawn meat was simulated. Moreover, the change of Ca²⁺ -ATPase activity and solubility of protein was measured during heat treatment and the correlation with protein denaturation degree was examined.
[Result] Denaturation kinetic parameters (activation energy, frequency factor) of myosin and actin in kuruma prawn protein were determined by DSC- dynamic method. The denaturation distribution of protein was non-uniformly during both heating conditions (51°C and 85°C). When heated at 51°C, myosin denatured slowly, actin did not denatured. When heated at 85 °C, myosin was completely denatured in 160 s, actin in 495 s. Ca²⁺-ATPase activity decreased with increasing heating time at both temperatures, it was found to be associated with the average degree of protein denaturation. Solubility the protein was also found to be strongly correlated with the average degree of protein denaturation.

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Analysis of localization of catechins in tea leaves
Chihiro Takatsuka¹, Yasuo Niwa², Yuji Moriyasu³ (¹Tokai University Junior College, ²Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, ³Graduate School of Science and Engineering, Saitama University)
[Object] Plants contain various phenolic compounds. It is known that leaves of tea (Camellia sinensis) contain a large quantity of catechins. The catechins in tea have antioxidative and antibacterial properties, which are believed to have a function of protecting the leaves from UV rays, molds, and pests. As dietary components, catechins are bitterness components of tea. It is considered that color tones of oxidized catechins make a large contribution to the color of tea when it is brewed up. Moreover, catechins are highly expected as compounds to provide health effects on humans such as prevention of cancer and influenza. However, not many researches have been conducted to study how tea catechins are present in plant cells. Thus, the localization of the tea catechins in plant cells has remained unknown. The object of this study was to reveal the localization of catechins in tea leaves via light and electron microscopic observations of tea leaves.
[Method] Leaves of tea (variety: Yabukita) was immobilized with glutaraldehyde and osmic acid, dehydrated, and then embedded in Spurr’s resin. From the leaves thus treated, sections sample were prepared with a microtome. Then, light and electron microscopic observations were conducted on the section sample.
[Results] The optical microscopic observation of the tea leave showed that catechins stained in dark brown were present in mesophyll cells. Then, the electronic microscopic observation of tea leaves showed that black aggregates, which are considered as catechins, were present in large vacuoles. The black aggregates of catechins are various in shape and size. Apart from the large vacuoles containing catechins, there were small vacuoles containing catechins.
[Conclusion] Catechins are mainly localized in the vacuoles of mesophyll cells in tea leaves.

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