The relationship between the protein composition of rice and nitrogen compounds (amino acids and oligo-peptides) in the produced sake were investigated using endosperm protein mutant rice (LGC-1, ...LGC-Jun, Kx433, QA28), sake rice (Yamadanishiki) and cooking rice (Nipponbare, Nihonmasari, Koshihikari). The total nitrogen concentration, amino acid concentration and most peptide peak areas determined by RP-HPLC and gel filtration chromatography of the produced sake were lower when sake was made from a low glutelin content rice mutant compared with other rice varieties. The concentration of nitrogen compounds in the sake positively correlated with the glutelin content of the highly milled rice grains used for sake production. Sake produced using a low glutelin content rice mutant is generally evaluated as having a light taste. Our findings suggest that nitrogen compounds (oligo-peptides and amino acids) derived from rice glutelin significantly contribute to the taste of sake.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Using rice grains contaminated with radioactive cesium (134Cs and 137Cs) that was released by the Fukushima Daiichi Nuclear Power Plant Accident in March of 2011, we investigated the behaviors of the ...radioactive cesium and potassium (total K and 40K) during sake brewing. Cesiumis a congener of K, and yeast cells have the ability to take up Cs using known K transporters. During rice polishing, the concentrations of radioactive Cs and K in the polished rice grains decreased gradually until a milling ratio (polished rice weight/brown rice weight) of 70% was reached. No significant changes were observed below this milling ratio. Sake was brewed on a small scale using the 70% polished rice. The transfer ratio of radioactive Cs to sake and to the sake cake was significantly different than the ratio of K. Approximately 36% and 23% of radioactive Cs in the polished rice was transferred to the sake and sake cake, respectively; however, 40% was removed by washing and steeping the rice grains. On the other hand, 25% and 40% of K in the polished rice was recovered in the sake and sake cake, respectively, and 35% was removed by washing and steeping the rice grains. From the present results, the concentration of radioactive Cs in sake would be 4 Bq/kg fresh weight, which is well below the regulation values (100 Bq/kg), even using brown rice containing 100 Bq/kg of radioactive Cs.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Possible contamination by radioactive cesium (Cs), released by the Fukushima Daiichi Nuclear Plant Accident in Japan on March 2011, has been a matter of concern with respect to Japanese sake made ...from rice grains cultivated in affected fields. In this study, the behavior of stable 133Cs, which is a useful analogue for predicting the behavior of radioactive Cs, was investigated in the production of sake using rice grains harvested in Japan in 2010. The concentration of stable 133Cs in the polished rice grains decreased gradually with decreasing milling ratios until a ratio of 70% was reached, and below that point, it did not change significantly. The 133Cs concentration in the 70% polished rice was approximately 20% of that found in brown rice. The sake was brewed on a small scale using 70% polished rice, and the transfer of 133Cs from rice to sake was examined. Approximately 30–40% of 133Cs in the 70% polished rice was removed during the washing and the steeping of the rice grains, and approximately 40% of the 133Cs in the 70% polished rice was transferred to the sake. If the radioactive Cs species behaves similarly, these results suggest that brown rice containing 100 Bq/kg radioactivity of Cs would generate 70% polished rice grains containing 20 Bq/kg and that the sake brewed from these grains would contain 3–5 Bq/kg.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
ABSTRACT
The influence of nitrogen and sulfur compounds in rice grains on changes in flavor in stored sake was investigated using Japanese rice cultivars for sake making. Nitrogen content exhibited a ...significant positive correlation with sulfur content. Based on the molar ratio of nitrogen to sulfur in the rice grain, the sulfur compounds appeared to be derived from protein‐associated sulfur‐containing amino acids, as reported previously. The higher the protein content of the rice, the greater the amount of nitrogen and sulfur compounds found in both the digest of steamed rice grains and in the sake. Physicochemical changes were investigated in the stored sake to confirm the influence of total sulfur content. Polysulfides in the stored sake appeared to be higher when made from rice grains of high total sulfur content. Staling of stored sake was affected by levels of protein‐associated sulfur‐containing amino acids in the rice.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Background and objectives
Protein composition analysis of 81 rice samples was performed on three cultivars harvested different regions in Japan, and the effects of the protein composition on the ...nitrogen composition in sake.
Findings
Crude protein content showed a significant positive correlation with glutelin content. Yamadanishiki cultivars showed lower crude protein and glutelin contents compared with Gohyakumangoku cultivars harvested from the same field. Total nitrogen content in the enzyme digest of steamed rice grains showed a significant positive correlation with the crude protein and glutelin contents. Ten polished (70%) white rice samples were investigated in a small‐scale sake brewing test. Total nitrogen compounds, bitter‐tasting peptides, and free amino acids in the brewed sake positively correlated with the glutelin content of the rice samples. There were no clear correlations between α‐amylase and acid proteinase activities with the nitrogen compounds in the sake.
Conclusions
The results indicated that the glutelin content in the cultivar rice affects sake quality through taste‐active and other nitrogen‐containing compounds produced from rice glutelin in the sake brewing process.
Significance and novelty
We revealed that the glutelin content in the milled rice grains is important to brew high quality of sake clearly. The present results would be useful for cultivation or breeding of sake rice.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Thai non-broken rice has been mainly used for the production of awamori after 2010. It is more difficult to absorb water ideally than for Thai broken rice, which has been mainly used for a long time. ...This difficulty in absorption for Thai non-broken rice has recently demanded on immediate solution. In the present study, to obtain the basic knowledge for improving the absorption of Thai non-broken rice, we examined the suitability of Thai rice used for awamori production compared with Nipponbare, which is used for sake making. The property of Thai rice starch by RVA analysis was significantly different from that of Nipponbare. The water absorption ratio of rice showed a negative correlation with the moisture of rice grains in both Thai rice and Nipponbare. However, the ratio of water absorption of Thai rice was lower than that of Nipponbare, when the moisture of the rice was same. The speed of water absorption was significantly improved by pulverizing the rice grains when the steeping time was short. Two steamings also significantly improved the ratio of water absorption of steamed rice and enzyme digestibility. From the above results, we recommend that prevention of an increase in the moisture of rice grains is important to deal with Thai rice appropriately. Also, sufficient steeping time, or two steamings are effective to achieve the ideal ratio of water absorption when using Thai rice.
Some oligopeptides and amino acids have a strong influence on the sensory qualities of sake, but the formation process of such compounds in sake mash has not been well elucidated. In this study, we ...investigated the formation process of bitter-tasting peptides derived from rice proteins in sake mash, because knowledge about their formation may contribute to the quality control of sake. We analyzed rice protein hydrolysates in sake mash, as well as in the enzymatic digest of steamed rice grains digested by either sake-
koji or by crude enzyme extracted from sake-
koji. SDS–PAGE showed that a smaller amount of polypeptides (>
M.W. 10,000) accumulated in the supernatant of sake mash than in either enzymatic digest. The concentration of peptides in the supernatant of sake mash increased gradually from the early stages of fermentation. Five bitter-tasting peptides (No. 9, <
QLFNPS; No. 13, <
QLFNPSTNP; No. 17, <
QLFNPSTNPWH; No. 18, <
QLFNPSTNPWHSP; No. 20, <
QLFGPNVNPWHNP), which were previously found in sake mash, were not found in significant amounts in sake
-koji. On the other hand, these peptides accumulated at the early stages of both sake mash fermentation and the enzymatic digests, although the levels in sake mash were higher than those in the digests. The present study demonstrated that the 5 bitter-tasting peptides formed in high concentrations when steamed rice grains were digested under conditions of sake mash fermentation with yeast.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In the present study, we investigated the estimation method for the enzyme digestibility of steamed rice grains for sake making using alkali / urea solubility. Visual observation of the alkali / urea ...concentration solubilizing rice grains showed significant correlations with the DSC(= Differential Scanning Calorimeter)gelatinization temperature, the enzyme digestibility of steamed rice grains, and the retrogradation of steamed rice grains. The absorbance of iodine staining after soaking rice grains in urea solutions measured using a spectrophotometer also showed significant correlations with the enzyme digestibility of steamed rice grains and the retrogradation of steamed rice grains. Therefore, the enzyme digestibility of steamed rice grains for sake making can be estimated easily by the alkali / urea concentration solubilizing rice grains and the absorbance of iodine staining after soaking the rice grains in a urea solution. However, the polishing ratio and the moisture content of rice grains influenced the urea concentration solubilizing rice grains, although the existence of a white-core did not. In conclusion, these methods will be useful to estimate the enzyme digestibility of steamed rice grains for sake making, if the estimation standards according to the polishing ratio and moisture content of the rice grains can be determined.