In soy sauce production, histamine, which causes allergy-like food poisoning, has become a problem. As a countermeasure against the proliferation of wild lactic acid bacteria responsible for histamine formation, a new lactic acid bacterial strain, Tetragenococcus halophilus MS0204, was isolated from soy sauce moromi in Miyazaki prefecture. The efficacy of adding MS0204, which does not produce histamine, as a starter culture was investigated, and it was confirmed that its use suppressed histamine production. Furthermore, sensory evaluations indicated that the quality of soy sauce produced with MS0204 was comparable to or superior to that of additive-free soy sauce. These findings confirm the suitability of this novel lactic acid bacterium as a starter for soy sauce production.

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.

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 °C water (control) or 65 °C 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. (Received Dec. 3, 2024 ; Accepted Dec. 19, 2024)