Baker's yeast (Saccharomyces cerevisiae) is one of the most essential ingredients in bakery products. During the commercial baking process, baker's yeast is subjected to baking-associated stresses such as high-sugar concentrations, air-drying and freezing. These stresses significantly influence cell growth and fermentation. To avoid lethal damage, yeast cells need to adapt to the harsh environments. In order to clarify which genes are important for adaptation to stresses, a functional genomics analysis was carried out under stress conditions that simulated those occurring during the fermentation of dough and the production of dried yeast. Gene expression profiles indicated that many genes are involved in stress tolerance in yeast. In particular, it was suggested that the folding of intracellular proteins and the removal of denatured proteins play important roles in yeast cells under stress conditions. Additionally, it was suggested that the increased expression of genes involved in energy production is important for adaptation to stresses. We expect that these gene expression profiles accelerate improvements in the breeding of baker's yeast that has higher tolerance to stresses.

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The instrumental analytical value and the organoleptic value (n=576) of 18 representative raw cod roe samples were used to investigate the possibility and the limitation to apply the covariance structure analysis (CSA) as one of the evaluating methods of palatability. Three causal models were obtained as follows : 1) the evaluation of the appearance of the samples, 2) the evaluation of taste, flavor and texture, and 3) an integrated model of the models 1) and 2). The palatability of raw cod roe was found to be affected by three factors, “appearance”, “smoothness”, and “seasoning”, while the overall preference except appearance was affected by three factors such as “cod roe flavor”, “smoothness”, and “seasoning”. In applying this method, the value of chi-square test is considered to be improved by using a perceptual numerical value and a logarithmic value having linearity as input variables in an instrument analysis and adapting a line scale. The expansion of the applicable scope of the CSA to product development would require further investigations into the processing method and the applicable possibility to the sensory evaluation data whose number of the samples is less than 200, which is generally required for the covariance structure analysis.

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Light-colored soy sauce (Usukuchi shoyu) is usually used for seasoning boiled dishes (Nimono). Although Usukuchi shoyu contains more NaCl by about 2% than Koikuchi shoyu, many Nimono cooked with Usukuchi shoyu contain less NaCl than those cooked with Koikuchi shoyu. This cooking phenomenon of Usukuchi shoyu is experientially well known, and called as “Usukuchi shoyu paradox”. In this paper, we studied the mechanisms of Usukuchi shoyu paradox by two organoleptic evaluation methods. Firstly, we determined the discrimination threshold of saltiness in two kinds of shoyus, and the concentration of NaCl in each shoyu was significantly discriminated at 0.92% and at 0.95% in Usukuchi shoyu (p<0.05), and at 0.92% and at 0.97% in Koikuchi shoyu (p<0.001), respectively. Furthermore, dried bonito soup stock (Katsuo-dashi) was significantly discriminated at 1.00% and at 1.25% in Usukuchi shoyu (p<0.01), and at 1.00% and at 1.50% in Koikuchi shoyu (p<0.05), respectively. Also, the discrimination threshold of the taste of seaweed soup stock (Konbu-dashi) was less concentrated in Usukuchi shoyu than in Koikuchi shoyu. Secondly, the enhancing effect of saltiness was determined with probit method when Katsuo-dashi, Usukuchi shoyu and Koikuchi shoyu were combined. Sample 1 was prepared as a combination of 4% of Usukuchi shoyu and 3% of Katsuo-dashi, and the saltiness of sample 1 was equivalent to 0.90% NaCl solution when the NaCl concentration of sample 1 was 0.872%. Sample 2 was prepared as a combination of 4% of Koikuchi shoyu and 3% of Katsuo-dashi, and the enhancing effect of saltiness was not confirmed. Although 4% of Usukuchi shoyu, 4% of Koikuchi shoyu, and 3% of Katsuo-dashi did not show the enhancing effect of saltiness individually, the 95% confidential limits reinforced that only the combination of Usukuchi shoyu and Katsuo-dashi enhanced saltiness. In conclusion, the mechanism of Usukuchi shoyu paradox was suggested as follows : Usukuchi shoyu had a lower threshold for saltiness, which makes it easier to adjust appropriate saltiness required for Nimono and a combination of Usukuchi shoyu and Katsuo-dashi enhanced saltiness. Therefore, Nimono cooked with Usukuchi shoyu would be palatable with less salt.

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Kurozu is a food which has been traditionally made in Kagoshima and it is noted that kurozu has many physiological activities. In this paper, the anti-hyperglycemic effect of kurozu moromi powder (Kmp), the fermentation residue of kurozu, was examined by using type II diabetic model KK-A^y mice. Mice fed normal diet or normal diet with 0.5% Kmp or normal diet with 0.01% pioglitazone (Pio) for 51 days. The blood glucose level of Pio group significantly decreased after the day 10, but that of Kmp group decreased after the day 40 against the control group. Serum total cholesterol (T-CHO) and triglyceride (TG), and muscle T-CHO significantly decreased in Kmp group and Pio group. Liver TG significantly decreased only in Kmp group. The translocated-glucose transporter 4 (GLUT4), peroxisome proliferator-activated receptor α (PPAR α), and phosphorylated-AMP-activated protein kinase α (AMPKα) in muscle increased in Kmp group and Pio group. The insulin receptor β (IRβ) increased in Kmp group and phosphorylated-IRβ increased in Kmp group and Pio group in liver. The PPARγ increased in Pio group, but it decreased in Kmp group in adipose tissue. These results suggested that Kmp could be an effective food for the prevention of hyperglycemia and hyperlipidemia.

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Estimation method of mixing ratio of materials in processed foods by amino acid patterns were invented by Tamura et al. (the traditional way). It shows the ratio of buckwheat protein in dried buckwheat noodles as follows :
α′_T=
{∑a_i^Np_i^N∑(b_i^N)²−∑a_i^Nb_i^N∑b_i^Np_i^N}/{∑a_i^Np_i^N[∑(b_i^N)²−∑a_i^Nb_i^N]+∑b_i^Np_i^N
[∑(a_i^N)²−∑a_i^Nb_i^N]}:(A)
α′_T is the ratio of buckwheat protein. a_i^N, b_i^N and p_i^N are the amounts of amino acids of buckwheat, flour, and a sample, respectively. The summation of a_i^N, b_i^N and p_i^N is standardized to 1. In short, the equation (A) is not estimating the mixing ratio of buckwheat as weight ratio in dried buckwheat noodles, but gives “protein” ratio. We devised the estimation method of the mixing ratio of buckwheat as weight ratio (the improved way). The equation is as follows :
α′=
{∑(AVERAGEa_i)p_i∑(AVERAGE b_i²)−∑(AVERAGE a_i)(AVERAGE b_i)∑
(AVERAGE b_i)p_i+[(X_p−X_b)/X_a] [∑(AVERAGE a_i)(AVERAGE b_i) ∑
(AVERAGE a_i)p_i−∑(AVERAGE a_i²) ∑(AVERAGE b_i)p_i]}/
{∑(AVERAGE a_i)p_i∑(AVERAGE b_i²)+∑(AVERAGE a_i)(AVERAGE b_i)∑
(AVERAGE b_i)p_i−(X_b/X_a)[∑(AVERAGE a_i)(AVERAGE b_i) ∑(AVERAGE a_i)p_i−∑(AVERAGE a_i²) ∑(AVERAGE b_i)p_i]}: (B)

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Angiotensin I-converting enzyme (ACE) inhibitory peptides were prepared by extracting tamari shoyu residue with alkali, followed by chromatography on Diaion AMP 01 and Toyopearl HW-50F. The amino acid sequence of the four kinds of ACE inhibitory peptides were determined after successive chromatographic isolation on reverse phase HPLC. Leu-Val-Gly and Phe-Glu-Thr-Arg, which showed strong ACE inhibitory activity among these peptides, showed significant reduction in systolic blood pressure when they were orally administered to spontaneously hypertensive rats in a single dose (5mg/kg of rat weight). These results suggest that administered Leu-Val-Gly and Phe-Glu-Thr-Arg lowered systolic blood pressure by suppressing ACE activity.

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[in Japanese]

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