Shiikuwasha (Citrus depressa Hayata) has attracted attention in recent years for its anti-cancer, anti-inflammatory, and other health-promoting properties, leading to a rapid increase in demand and a chronic shortage of fruit for processing. To compensate for this shortage, adulteration of shiikuwasha juice with calamondin (Citrus madurensis Lour.) juice has become a major concern. The aim of this study was to develop a reliable methodology to assess the authenticity of shiikuwasha juice. The developed approaches include: (1) sensory evaluation, a low-cost and direct technique capable of detecting contamination levels above 50 % in calamondin juice; (2) a thin-layer chromatography (TLC) method developed to detect 3',5'-di-C-β-glucopyranosylphloretin, a chemical marker specific to calamondins; and (3) high performance liquid chromatography (HPLC) and solid-phase microextraction–gas chromatography (SPME-GC) methods to identify polymethoxyflavonoids and γ-terpinene, the main characteristic compounds of shiikuwasha, as chemical markers. To further ensure product authenticity, DNA marker-based methods have also been developed. It is anticipated that these evaluation methods will be extensively employed in a wide range of fields, from production and processing to distribution, in order to accurately identify shiikuwasha products.

We propose a method for calculating the temperature distribution in food containers by considering various heat transfer coefficients during heat sterilization. The CIHC method is a calculation method that incorporates the heat transfer coefficient, accounting for various heat transfer coefficient patterns on the container’s surface and container's thickness, to numerically calculate the temperature distribution inside the container during heat sterilization of food. In such sterilization processes, steam, pressurized air, and hot water are commonly used as heat transfer media at different flow rates for the sterilization of heat-sealed plastic cups and glass jars. Furthermore, the container material may exhibit high thermal insulation and be relatively thick. In the CIHC method, we represent the heat transfer coefficient as the thickness of the solid layer covering the container surface. To validate this method, we conducted an experiment using cylindrical plastic cups with three different thicknesses (0.5 mm, 1.0 mm, and 2.0 mm). We filled these cups with gelatinized starch and sterilized them at 120 °C. for 30 minutes using a hot water immersion method. Using the temperatures in the sterilization chamber, we calculated the temperature distributions inside the gelatinized starch. The results suggested that the CIHC method is effective, as the calculated Fo values closely matched the measured values, and the root mean squared errors for evaluating the time course of the temperature distribution were approximately 2 °C.

The objective of this study was to develop tofu-like foods using the okara by-product of tofu production and to elucidate the physicochemical and sensory characteristics of these foods. First, okara subjected to high-pressure heat treatment at 120 °C for 15 min was digested using food enzymes such as cellulase, hemicellulase, and pectinase. The fibers in okara were effectively decomposed by 1.0 % (w/w) Celluclast^®1.5 L, 1.0 % (w/w) Viscozyme^®L, and 1.0 % (w/w) Pectinase SS. Next, tofu-like foods were prepared by adding polysaccharides to the obtained okara milk. The addition of κ-carrageenan [0.7–0.8 % (w/w)] and xanthan gum or guar gum [0.2 % (w/w)] was suitable for producing tofu-like foods with a texture comparable to commercially available (CA) soft tofu. The L* and b* values for tofu-like foods were significantly lower than those of CA soft tofu, suggesting that browning occurred by high-pressure heat treatment. Except for the tofu-like food prepared with 0.8 % (w/w) κ-carrageenan and 0.2 % (w/w) guar gum, the tested tofu-like foods exhibited the same breaking force and adhesiveness as CA soft tofu. Sensory analysis revealed that tofu-like food with a smooth and soft texture could be produced by adding 0.7 % (w/w) κ-carrageenan and 0.2 % (w/w) xanthan gum. These findings may provide valuable information for upcycling okara to reduce food loss and waste.