Frozen vegetables are very useful as food materials. However, most of the vegetable content is moisture, and ice crystals produced during the freezing process injure the vegetable cells and generate a large amount of drip during freeze-thawing, thereby causing deterioration. If the growth and aggregation of intracellular ice crystals during vegetable freezing are reduced, it may prevent deterioration by decreasing drip emission. In the present study using cryo-scanning electron microscopy, we investigated how the shape of ice crystals in frozen tissues of raw and branched vegetables (Japanese white radish, potato, broccoli, and pumpkin) could affect drip emission during thawing after three kinds of freezing treatments (A, liquid nitrogen freezing; B, air blast freezing; C, windless freezing). The drip ratio (mL/g vegetable) was increased most by method C, followed by B and A. The cytoplasmic membrane structures and sol of raw vegetable cells were not broken by method A, whereas the structures were broken considerably by method B and remarkably by method C. Fine ice particles in blanched potato seem to depend on the vitrification phenomenon of starch. Ice crystal growth in frozen vegetables was reduced by blanching, and a tendency for the drip ratio to decrease was observed in all vegetables except for pumpkin.

This study identified functional ingredients in the pericarp, both the albedo and the flavedo, of Citrus maxima, which is a special product of Kumamoto Prefecture, Japan. First, the proximate composition and dietary fiber contents of the heat-dried pericarp of C. maxima were determined. It was found that the heat-dried pericarp contained 15.0g/100g of soluble and 18.8g/100g of insoluble dietary fibers. Next, the effect of the heat-dried pericarp on blood glucose levels in male Wistar rats was investigated. The results indicated that the heat-dried pericarp contained components capable of both increasing and decreasing blood glucose levels.

For the effective utilization in processed foods of unripe apple, the physicochemical characteristics of unripe apple starch were examined. Unripe apple starch had lower amylopectin content and a smaller particle size than the starch of other crops. This result indicates that unripe apple starch has a low viscosity during gelatinization. In addition, the phosphorus content was lower than in other crop starch, suggesting that it tends to be difficult to separate from water in addition to its low viscosity. These results suggest unripe apple starch can be used in processed foods where such physical properties are required.

The hypolipidemic effects of soybean and soy components have been clarified through numerous epidemiological and experimental studies. Soybean and soy foods contain various nutritional and functional components; thus, this complexity impedes understanding of their global functionality. To address this issue, we attempted to clarify the major active component of kori tofu (freeze-dried soybean curd) and its mechanism of action on modulating lipid metabolism in rats. The results suggested that the protein component played the principal role in reducing serum lipid levels through suppression of hepatic lipogenesis. Moreover, we attempted to reveal the hypolipidemic properties of four soy foods by comparing several parameters involved in lipid metabolism. Although the differences among the soy foods were not always obvious, the quantity and quality of some components, such as protein and dietary fiber, seemed to determine their hypolipidemic properties. Therefore, the moderate hypolipidemic effects of soy foods and their habitual consumption may contribute to improved lipid metabolism.

Kori-tofu is a traditional food in Japan. Kori-tofu is known to decrease serum LDL-cholesterol and triacylglycerol. Kori-tofu also decreases HbA1c, indicating improved sugar metabolism. A dominant hypothesis regarding these phenomena is that the undigested protein fraction of kori-tofu (resistant protein) binds to bile acids in the intestine, preventing bile acid resorption. Recent studies have shown that bile acids are a type of signaling molecule that activates FXR and TGR5. This can explain why the binding activity of bile acid, involving resistant protein, relates to lipid and sugar metabolism. Resistant protein in kori-tofu is increased during its production process, including high-pressure treatment of fresh tofu, freezing and low-temperature aging. The abundance of resistant protein can explain the function of kori-tofu.