In efficient production of food with high quality, adoption of appropriate reaction and separation processes and their optimization are always required. Membrane separation technologies such as microfiltration, ultrafiltration and reverse osmosis have many advantages over other separation technologies because they require less energy and no heat treatment. Their application to food industries has been developed successfully in Japan. Recently nano-filtration technology which is a new category of membrane technology placed between reverse osmosis and ultrafiltration is attracting a great deal of attention. In this paper, study on optimization of these membrane separation processes for liquid food will be introduced in the former half of this paper. Biodiesel fuel （fatty acid methyl ester） is a replacement for diesel fuel produced from vegetable oil. In Japan, only used edible oil and by-products from oil refining process can be materials for biodiesel fuel because we need to import most of edible oil from foreign countries. However, these materials can not be converted in to biodiesel fuel with conventional alkaline catalyst method because free fatty acid contained in the materials inactivates the catalyst. A new method which does not require any alkaline catalyst will be introduced and its economical efficiency will be demonstrated in the latter half of this paper.
We report for the first time on wormlike micelle formation in aqueous mixtures of lysophosphatidylcholine (LPC) and phosphatidylcholine (PC). The viscosity of mixtures of these two phospholipids at total concentrations ≥56 mM showed a marked maximum around LPC molar fraction 0.5 - 0.7, which was ascribed to wormlike micelle formation. The diffusion coefficient of the lecithin, as measured using pulsed-field-gradient stimulated spin echo NMR, suggests that LPC and PC form spherical micelles and vesicle structures, respectively. In mixtures of LPC and PC, individual spherical micelles of LPC and a vesicle structure of PC were found at low temperature. Wormlike micelle formation was manifested in a steep decrease of the diffusion coefficient at temperatures above 55℃. The results indicate that a minimum concentration of both LPC and PC, as well as a molar ratio of LPC to PC close to 0.5-0.6, are prerequisite for thermally induced formation of lecithin wormlike micelles in aqueous solutions. Following formation on heating, the wormlike micelles remained stable on cooling, and no population of smaller spherical micelles could be detected.
Food hydrogel was produced from an oil in water emulsion of soy milk and rice powder mixture. We investigated the rheological properties during soy milk gelation with rice powder on addition of an acetic acid coagulant. The pH value of soy milk decreased on addition of rice powder and an acetic acid coagulant. Soy milk with rice powder formed a weaker gel with increasing concentration of soy milk and decreasing concentration of acetic acid coagulant. The frequency dependence of dynamic viscoelasticity suggested that soy milk formed hydrogel on addition of an acetic acid coagulant and rice powder. The time dependent changes in dynamic viscoelasticity suggested that palm oil retarded soy milk gelation early and then promoted it a little later. It was suggested that the oil droplet which was acting as an inactive filler acted as an active filler after that the first stage.
Food hydrogel was produced from an oil in water emulsion of soy milk and rice powder mixture, and a processing technique with freezing was investigated in terms of the rheological properties of the resultant products. The emulsion specimens were stored at 4℃, −5℃, −10℃ and −20℃ for 1 day. The time dependent changes in dynamic viscoelasticity suggested that the gel formation above freezing point, that was 4℃, allowed to form a gel network covering its bulk specimen. Whereas, when the specimens were aged in frozen state, gel formations could occur at localized positions due to the geometrical limitation by ice. The characteristics of viscous liquid could be confirmed in these specimens by the linerly increased loss tangent values, and this trend was obvious in the order of −5℃, −10℃ and −20℃. Gel specimens were cooked with an oven at 180℃ in order to observe their melting behavior. It was found that the degree of melting correlated to the rheological properties, and this correlation was obvious when gels were aged at −10℃. The results of this study suggested that freezing could be a useful processing tool for tuning rheological properties of food hydrogels, that may allow to process food functionalities.
The quality of spaghetti, given the same raw materials, will vary depending on the extrusion rate, pressure, and drying conditions during manufacture and at the time of opening of the package. In this study of spaghetti of several types produced with different manufacturing conditions, mechanical properties were ascertained using the compression test to identify the factors that influence spaghetti quality. Furthermore, characteristics of ordinary dry spaghetti and raw spaghetti, which is said to provide excellent taste, produced in a research laboratory are compared to assess the differences of food textures quantitatively. Identification of these factors is expected to improve the food texture of spaghetti.