Drying is a food processing operation that reduces post-harvest losses of agricultural products. Although drying consumes a large amount of energy, vacuum microwave drying reportedly uses less energy than other drying methods, potentially reducing environmental impacts. However, a quantitative evaluation of the environmental impact of vacuum microwave drying has not yet been reported. Therefore, we conducted experiments on kiwifruit dried using vacuum microwave drying and evaluated the environmental impact of producing 100 g of dried kiwifruit by a life cycle assessment (LCA) method. We also calculated the losses generated during the drying process and performed a sensitivity analysis. The results showed that in the production of 100 g of dried kiwifruit, the processing stage contributed the most in 15 of 16 impact categories. Within the processing stage, electricity consumption during drying had a large impact. These results suggest the potential for reducing environmental impacts by decreasing electricity consumption during the drying process. The sensitivity analysis results indicated that consideration of the loss ratio is important in environmental impact assessment, as the interpretation of the results depends on the how the loss ratio is defined.

Recently, the environmental impact of large amounts of waste and by-products generated from agricultural products has become a serious issue. Food waste, in particular, presents not only environmental challenges but also economic concerns. As part of the Sustainable Development Goals (SDGs), a target has been set to halve per capita global food waste by 2030. In this context, ongoing research aimed at the effective utilization of unused plant resources, including food waste, non-edible parts of agricultural products, and by-products, has been carried out. For over 20 years, the author has conducted various studies, primarily from an analytical chemistry perspective, focusing on unused food resources often discarded or underutilized. The research has specifically targeted unused plants, analyzing their components (including polyphenols) and evaluating their functional properties to provide scientific evidence for their biological activities. This article highlights some of these research findings. In particular, the studies have focused on unused agricultural products such as wasabi leaves, fruit peel of akebi, anthocyanin-rich food materials like berries, and bee products such as propolis and bee pollen.

When food products and solutions are vacuum packaged together using a chamber vacuum packaging machine, the pressure differential created during the process can drive the solutions into the pores of the foods. This study investigated the potential of vacuum packaging as a novel seasoning method for raw vegetables. Four kinds of vegetables were immersed in NaCl solutions isotonic to their intracellular fluids and then vacuum packaged. The results suggest that vacuum packaging facilitates seasoning by promoting the influx of NaCl solution into vegetable pores, including the intercellular spaces, without compromising cell-membrane integrity. Additionally, the effectiveness of this method was found to be influenced by the porosity and structural conditions of the vegetable pores.

Whey protein concentrate (WPC) has been used in the manufacturing of yogurt to improve its physical properties. However, the addition of WPC alone does not provide sufficient water-holding capacity in yogurt. In this study, an olive leaf water extract (OLEx), which improves the gelling properties of egg white protein and gelatin, was applied to WPC-fortified yogurt, and the effects of WPC added with OLEx (OLEx-WPC) on the physical properties of yogurt were investigated. First, we investigated the physical properties of heat-induced WPC gel containing OLEx. The breaking stress for OLEx-WPC gel increased, and the syneresis ratio for OLEx-WPC decreased compared to WPC without OLEx. SDS-PAGE analysis showed that OLEx polymerizes protein components in WPC. The breaking stress for WPC-formulated yogurt with OLEx increased compared to that without OLEx (control group). The syneresis ratio for yogurt was much lower in the treatment group than in the control group. These results indicate that OLEx is useful for improving the mechanical properties and water-holding capacity of WPC-formulated yogurt.

The purposes of this study were to develop a method that can predict age gelation at an early stage during long ambient storage of directly heated UHT milk, and to verify suppression effect of heating conditions before sterilization. To analyze the casein degradation that cause gelation, sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) and high performance liquid chromatography (HPLC) were performed after milk was stored at 5, 25, and 37℃ for 2 and 4 weeks. Also, each milk sample was stored at 25℃ for 6 months to confirm the occurrence of gelation. Age gelation that occurred after 5-6 months at 25℃ could be predicted by SDS-PAGE and HPLC analyses of the milk stored for 2 and 4 weeks at 25 or 37℃. We also confirmed that heating conditions before sterilization which had not been previously reported, could suppress gelation.

A randomized crossover study was conducted to determine whether there were differences in changes in body temperature, autonomic nervous system activity, and subjective thermal sensation after the ingestion of hot soup between subjects with and without cold constitution. The subjects were 20 young women, 10 each in a cold constitution group (CC) and a non-cold constitution group (Non-CC). The subjects ingested 150 mL of 37 ℃ water (control) or 65 ℃ hot soup in the morning on different days after overnight fasting and were evaluated up to 60 minutes after ingestion. After the ingestion of hot soup, toe temperature was transiently significantly higher than the control, irrespective of constitution groups, and remained higher until 60 minutes in the CC, but tended to reverse between the hot soup ingestion and control in the non-CC. No significant differences in intra-aural or finger temperatures, autonomic nervous system activities, or subjective thermal sensations were found between constitutions after the ingestion of hot soup. These results suggest that the increase in toe temperature due to hot soup ingestion is more sustained in subjects with than without cold constitution.

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.

To investigate whether converting soy milk into a soy milk espuma can reduce the maximum velocity of the food bolus in the pharynx, we investigated the relationship between the rheological properties of soy milk espuma prepared with 0.25–0.9 % (w/w) thickening-adjusting food (TAF) and the maximum bolus velocity. A similar experiment was carried out on foam produced by a hand mixer. Except for the addition of 0.25 % (w/w) TAF, the foaming power of the espuma was higher than that of the mixer foam. The espuma had microbubbles with a narrow size distribution and a large number of bubbles, whereas the mixer foam contained millibubbles and had a wide size distribution. As the TAF concentration increased, the apparent viscosity, adhesiveness, and storage modulus (G') of the espuma increased. In contrast, the adhesiveness and G' of the mixer foam decreased. The highest values obtained for these rheological properties were observed for espuma containing 0.9 % (w/w) TAF and mixer foam containing 0.25 % (w/w) TAF. At the same TAF concentration, the maximum velocity of the food bolus in the pharynx was the fastest for soy milk, followed by mixer foam, and slowest for espuma. Notably, the maximum velocity of the 0.9 % (w/w) TAF espuma was the slowest among all foam types.

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 ℃ 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 square errors for evaluating the time course of the temperature distribution were approximately 2 ℃.

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 ℃ 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 k-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.