Recently, raw soy sauce without heat sterilization was developed and has become popular among consumers. Its sensory properties, however, have not been well studied. In this study, we aimed to reveal sensory differences between raw- and heated-soy sauces by conducting detailed sensory analysis. Quantitative descriptive analysis (QDA) was performed for 12 (6 raw/6 heated) commercially available soy sauces from six manufactures by 13 trained panelists. As a result, a total of 48 sensory attributes were identified. Statistical analysis revealed that raw soy sauce had stronger sweetness, umami and soy flavor, whereas heated soy sauce had stronger bitterness, astringency, metallic taste and bitter aftertaste. The differences in sweetness and bitterness of samples were supported by the results of chemical analyses. Further, we incorporated the 48 attributes into the 74 previously reported Japanese soy sauce attributes, for a total of 91 attributes. These 91 attributes were organized into a flavor wheel applicable to today’s Japanese soy sauce market. We also confirmed that the flavor wheel contained essential attributes commonly found in commercially available Japanese soy sauces and could effectively characterize these soy sauces. This is the first study to present sensory characteristics that can describe commercially available raw soy sauces. Furthermore, the schematization of soy sauce attributes will facilitate communication among stakeholders and contribute to the standardization, simplification and rapidity of Japanese soy sauce evaluation steps.

The 16S rDNA genotypes among lactic acid bacteria were determined using PCR-RFLP analysis. Eight tetrameric restriction enzymes (AccII, AfaI, HaeIII, HhaI, MboI, MspI, TaqI, XspI) were used for RFLP analysis and adequate numbers of informative band were obtained from each enzyme. Eighty-two genotypes were obtained from 99 lactic acid bacteria. In the case of only two restriction enzymes, sixty-five genotypes, which are most in all combination, were obtained from the combination of XspI and MspI restriction patterns. Therein, fifty-two species could be assigned to specific genotype, supporting the application of this analysis for identification of bacterial species. The genotype assigned by PCR-RFLP using XspI and MspI showed 92.3% successful phylogenetic affiliations. PCR-RFLP analysis using 20 lactic acid bacteria was demonstrated, and the results corresponded approximately to the calculated fragment patterns. These results indicate that PCR-RFLP should be useful for genotyping, identification and approximately classification of lactic acid bacteria.

Typically, low-protein rice and starchy rice are used in medical diets for patients with chronic kidney disease. In this study, we cooked 4 kinds of low-protein rice and starchy rice and examined their cooking properties and taste characteristics as well as observed the microstructure of the rice uncooked and cooked.

1. The moisture content of the low-protein rice and starchy rice had an effect on the added water volume and condition during storage.

2. By observation of the microstructure of the low-protein rice, we found that the sub-aleurone layer of the outer layer in low-protein rice was removed by processing. The starchy rice showed uniform microstructure.

3. The texture of the low-protein cooked rice indicated higher cohesiveness than the polished cooked rice; however, there were no differences in hardness and adhesiveness. The starchy cooked rice had a higher ratio in both hardness and cohesiveness but was lower in adhesiveness.

4. Regarding taste, sensory evaluation rated the low-protein cooked rice and starchy cooked rice as poor with low umami. In particular, the starchy cooked rice required improvement of its taste and texture.

Rice was cooked in tap water in a pot coated with powdered ceramic that radiates far infrared wavelengths. The amount of contained water and the sugar content of rice were investigated. The water content did not differ, whereas the sugar content increased compared to the control. Without pre-soaking of the rice, the total sugar content increased by 1.4 fold, whereas the glucose content, an important factor of sweetness, did not change. With 30 min pre-soaking of the rice, the total sugar content did not change, whereas the glucose content increased by 1.3 fold (not significantly different). These results suggested that the cooking of rice in a ceramic-coated pot could increase its flavor attributes. When pure water was incubated in the ceramic-coated vessel, the evaporation rate was slower than that of pure water incubated in a control pot. Therefore, it is possible that the ceramic properties alter the physiochemical nature of water. When a crude enzyme from rice was treated with ceramics, the hydrolytic activity of the starch enzyme increased at around 50°C．Thus, this suggests that the increased enzyme activity may be related to the increased sugar content.

Flavor development during natto fermentation was examined using GC/MS analysis. Steamed soybeans were inoculated with Bacillus subtilis (natto) as a starter, fermented for 3, 7, 12, and 18 hours, and the resultant natto products were subjected to GC/MS analysis. Steamed soybeans without starter were analyzed for comparison. MetAlign and AIoutput2 software were employed for semi-automatic GC/MS peak analysis and MS data processing to determine flavor compounds. As a result, a total of 38 volatile compounds were identified. Among these, 23 were also detected in the steamed soybean, revealing different effects during fermentation (6 compounds were reduced or disappeared during fermentation, 12 were relatively stable, and 5 were increased). Twelve flavor compounds including those constituting the major natto flavors, pyridines and branched fatty acids, were strongly induced during the late stage of fermentation.

Kagoshima no Tsubozukuri Kurozu was registered with the Japan Geographical Identification (GI) system on December 22, 2015. Kagoshima no Tsubozukuri Kurozu is a type of rice vinegar from Kagoshima Prefecture in southern Japan that is produced using a traditional method that has been handed down from one generation to the next. Tsubo and Kurozu are translated as earthen pots and black vinegar, respectively. The origin, history, and quality of GI-certified Kagoshima no Tsubozukuri Kurozu are reviewed herein.