Freeze-drying (lyophilization) is a drying method characterized by using sublimation as one of the dehydration principles. This paper presents an atmospheric freeze-drying technique, which is a freeze-drying process that does not use a vacuum condition. The characteristics of foods dried by atmospheric freeze-drying are introduced in terms of various properties, such as retention of vitamins, anti-oxidative properties, and lipid oxidation. It is expected to delay lipid oxidation during storage and retain food functional components, in addition to ensuring superior taste appeal, by applying appropriate processing conditions. By clarifying the significance of this process, we hope to suggest the potential of atmospheric freeze-drying as a food manufacturing technology for labor-saving production of high-quality products.

Increased oxidative stress in the adipose tissue of obese individuals causes abnormal glucose and lipid metabolism, leading to metabolic syndrome onset. Therefore, intake of food-derived antioxidants can effectively prevent metabolic syndrome. Peanut (Arachis hypogaea L.) seed coat is usually discarded in large quantities during processing because of its low economic value, but has been reported to contain a large amount of polyphenols with antioxidant properties. Therefore, in this study, we extracted peanut seed coat using black vinegar, which is also reported to have a high polyphenol content, and examined the effects on glucose and lipid metabolism in high-fat diet-induced obese mice. Six-week-old male C57BL/6J mice were fed a high-fat diet containing 60 kcal% fat and a black vinegar drink containing peanut seed coat extract diluted 40 fold (low dose: LD) or 20 fold (high dose: HD) for 20 weeks. As a result, the final body weight was significantly decreased in both the LD and HD groups compared with the control group. Fasting plasma triglyceride level was significantly lower in the HD group than in the control group. In the HD group, the homeostasis model assessment-insulin resistance (HOMA-IR) value and the quantitative insulin-sensitivity check index (QUICKI) value were significantly decreased and increased, respectively. These results suggest that the black vinegar drink containing peanut seed coat extract improves obesity and glucose metabolism.

Insufficient intake of n-3 polyunsaturated fatty acids (n-3 PUFAs) has invited health issues, such as cardiovascular and inflammatory diseases, in recent years. n-3 PUFAs include EPA and DHA, found in fish oils, and α-linolenic acid, found in plant oils. A reduced intake of fish has been reported among the Japanese people. Additionally, in many Western countries, fish is not regularly consumed. Therefore, vegetable oils high in α-linolenic acid can be consumed in order to increase the intake of n-3 PUFAs. The most common methods of intake are consumption of the oils raw, such as in dressings, or through their use in cooking, such as in stir-fries. Owing to its low oxidation stability, α-linolenic acid is unsuitable for heating. However, linseed oil has been reported to be safe for stir-fry cooking, if performed for a maximum of a 3 min heating period. Therefore, there is a possibility that other vegetable oils containing high α-linolenic acid can also be used for stir-fry cooking. At present, there are limited reports available on the effects of the differences in such oils or in stir-fry ingredients on oil degradation. This study measured the degree of oil degradation, using peroxide value, when vegetables (bean sprouts, carrot, and green pepper) were stir-fried using vegetable oils high in α-linolenic acid (flaxseed oil, perilla oil, and sacha inchi oil) and examined the appropriate combination of oils and ingredients. The results indicate that the oils can be safely used for stir-frying at 190 °C for 3 min. Furthermore, the use of carrots, accounting for 25% or more of the total ingredients to be stir-fried, significantly suppressed the lipid oxidation. It is, thus, expected that the use of vegetable oils high in α-linolenic acid for stir-frying can improve n-3 PUFAs deficiency.

It is difficult to predict the gonad weight and index of edible sea urchins from just their appearance. In this research, we attempted to develop a non-destructive method for evaluating the gonad weight and index of Strongylocentrotus nudus using a transmission-type near-infrared spectrometer, which is widely used for non-destructive evaluation of the internal quality of fruits and vegetables. Two hundred sixteen S. nudus samples were collected in the Pacific Ocean near Ishinomaki City and Onagawa Town, Miyagi Prefecture, in 2021 and 2022. The obtained near-infrared absorption spectra were analyzed by principal component analysis. The first principal component explained 90 % of the second derivative-processed spectra. A negative peak was observed in the first loading vector around 930 nm, which is known as the lipid absorption band. The partial least squares regression model using second derivative-processed absorption spectra successfully predicted gonad weight with a factor number of 4, correlation coefficient of 0.78, and standard error of 4.4 g. Similarly, for the gonad index, a partial least squares regression model using 4 factors showed a correlation coefficient of 0.76 and a standard error of 4.6 g/100 g. These results suggest that near-infrared spectroscopy can evaluate the gonad weight and index without harming or damaging live specimens. This is mainly due to measuring the lipids in the gonads. This method could be used for non-destructive, auto-sorting systems for wild and cultured sea urchins.

Previous research has demonstrated the effect of enzymatic hydrolysis on the emulsifying properties of soy protein isolate (SPI). The present authors previously reported on the preparation of stable emulsions by the addition of oil and vinegar to a commercial SPI hydrolysate. In this paper, emulsions prepared by the direct introduction of fruit juices from several tropical fruits to SPI were examined. The purpose of this research was to elucidate whether the production of stable emulsions such as those made with the proteolytic enzyme papain was possible by this method. Stable emulsions were obtained from papain and pineapple, kiwi, melon, fig, and unripe papaya fruit juices. The appearance of the emulsions, the SDS-PAGE patterns of hydrolyzed SPI, and the pseudo-plastic behavior of the emulsions varied depending on the type of fruit, fruit production area, fruit ripeness, the reactive conditions of the fruit juices, and SPI. A relationship between the decrease in 11S acid subunits and emulsion stability was suggested.

The aroma extract dilution analysis (AEDA) applied to the volatile fraction of fresh perilla leaves (Oba) revealed 11 odor-active peaks with high flavor dilution (FD)-factors (≥4). Among the perceived odorants, trans-1,2-dihydroperillaldehyde (DHP), which has a unique note, such as curry-like spicy, was a newly identified compound in the fresh perilla leaf. Although DHP does not necessarily have a high FD-factor, it was difficult to determine the perilla aroma; thus we were interested in its role in the fresh perilla aroma. Therefore, the role of DHP in perilla aroma was demonstrated by the causal model based on sensory evaluation and PLS regression analysis. Consequently, it was clarified that DHP is an aroma component that enhances the “refreshing feeling of perilla” and, also plays an important role in improving its palatability.