To establish an efficient extraction method for functional components from food materials, we developed a piece of equipment for increasing-decreasing pressure extractions, which utilizes the pressure difference caused by a flow of water. We extracted the functional components of green tea using this equipment. As a result, catechins, caffeine, amino acids, chlorophyll, and α-tocopherol were efficiently extracted from green tea at a room temperature (20～25℃) in a short time (15 min). In addition, significant antioxidant activity attributed to the green tea extracts was confirmed, which the ethanol concentration was more than 60 % (v/v). Although the concentration of chlorophyll decreased after storage for three months, the concentrations of the catechins, caffeine, and amino acids did not change significantly upon storage. Therefore, even though there was an issue regarding the retention of color owing to the decrease in chlorophyll, this method is suitable for the extraction and storage of functional components from food materials.
The specific heat of wheat flour was measured at four different moisture contents (9～18%) and five different temperatures (10～50℃), using twin isoperibol calorimeters. This type of calorimeter is suitable for specific heat measurements of liquids. In this study, wheat flour samples were added to water, and the specific heat of each sample suspension was determined at each measurement condition. An additive relationship exists between the specific heat of a food material, its composition, and the specific heat of each component. The specific heat of the sample (wheat flour) was determined from the specific heat of the sample suspension using the additive property of specific heats. Furthermore, the effective thermal diffusivity of the sample (wheat flour) packed bed was estimated by substituting the literature data of effective thermal conductivity, the measured data of specific heat of the sample, and the bulk density of sample packed bed. The effects of moisture content, temperature, and bulk density on these thermophysical properties of the sample were investigated, and we proposed predictive models for these properties.
In this study, the gamma-aminobutyric acid (GABA) -producing Lactobacillus buchneri 1001 strain, isolated from kaburazushi (a regional specialty food of Japan's Toyama Prefecture consisting of pickled fish, rice, and turnip), was employed to prepare fermented butter-like food. GABA was effectively produced during fermentation by inoculating sodium glutamate-containing fresh cream with L. buchneri 1001 together with Lactobacillus bulgaricus and Streptococcus thermophilus. Furthermore, using freeze-drying instead of the churning process traditionally used after fermentation resulted in the production of fermented butter-like food with high GABA content, as well as a greater amount of protein and carbohydrates. The resulting fermented butter-like food met compositional standards, and its organoleptic characteristics were found to be as good as those of commercially available products.