2023 Research results

1.Genetic architecture underlying proanthocyanidin composition in American hybrid grapes

Author

KOYAMA Kazuya, KONO Atsushi, BAN Yusuke, IWASHITA Kazuhiro, FUKUDA Hisashi, and GOTO-YAMAMOTO Nami

Abstract

Background and goals
Grapes accumulate proanthocyanidins (PAs), complex polymer mixtures of flavan-3-ol units, in the skin and seeds. The composition of PAs, including subunit ratio and polymer length, and total concentration, is important because of their relationship to sensory properties of grape and wine. It is known that the grape species Vitis vinifera and Vitis labruscana have remarkably different PA concentration and composition. A mapping population derived from a cross between V.labruscana and V.vinifera was used to provide insight into the genetic architecture of PAs, as well as that of PA skin and seed properties.
Methods and key findings
The composition of PA subunits at the terminal and extension positions in the hybrid population’s skin and seeds was examined in great detail. Hierarchical clustering analysis of PA profiles grouped PA variables into five main clusters. There were distinct clusters related to compositional differences in skin and seeds, such as the percentage of galloylated or trihydroxylated subunits, polymer length, and the total PA concentration. A quantitative trait locus (QTL) analysis revealed several different minor loci between skin and seeds, each contributing to the phenotypic variation of total PA concentration. A few major QTLs on linkage groups 1 and 17 were discovered to contribute to the phenotypic variation of PA composition in both skin and seeds.
Conclusions and significance
A distinct genetic architecture between PA composition and total PA concentration in interspecific hybrid grapes was found. In contrast to PA concentration, a similar genetic architecture of PA composition was observed between skin and seeds.

Source

American Journal of Enology and Viticulture, 74, 0740016 (2023)

2.Impact of storage conditions on the volatile aroma compounds of aged sake

Author

BOERZHIJIN Surina, ISOGAI Atsuko, and MUKAI Nobuhiko

Abstract

The current study reports the effect of storage length and temperature on the key aroma compounds of aged Japanese sake. In total, 41 bottles of commercial aged sake aged between 3 and 53 years, including 20 bottles of low-temperature (controlled at ≤ 15℃) aged sake and 21 bottles of ambient-temperature aged sake, were analyzed. The concentrations of sotolon, dimethyl trisulfide (DMTS) and 3-methylbutanal were greatly enhanced in ambient-temperature and peaked after 11–20 years of aging. While in low-temperature, the concentration of isoamyl acetate and ethyl caproate, the main compounds that contribute to the freshness of Japanese sake, were maintained above their odor thresholds (0.27 mg/L and 0.12 mg/L, respectively) in 3–30 years aging. Methional concentration decreased along with the aging time in ambient-temperature, while in low-temperature it increased up to 30 years of aging and declined afterwards. The results obtained in this study can be applied as a useful tool to regulate and optimize the aging methods of sake, furthermore, to predict the effects of storage time when applying different temperatures in the sake aging field.

Source

Journal of Food Composition and Analysis, 121, 105351 (2023)

3.Changes in sake making properties of rice grains during the two ways of rice polishing

Author

OKUDA Masaki, TAKAHASHI Kei, BAO Hong-Bin, KOHNO Hiromi, JOYO Midori, MUKAI Nobuhiko, KINOSHITA Yasuaki, ENOMOTO Yasuhiro, YOSHIOKA Toshiaki, IWAMOTO Osamu, EBI Katsuya, and TAMEHISA Hirobumi

Abstract

The influences of rice polishing conditions on the rice properties for sake making were investigated. The rice grains were polished in the following two ways: a (#90 program) fine grind stone roll (#90), and a lower roll rotation speed and higher electric current, a (#60 program) usual grind stone (#60), and a normal roll rotation speed and normal electric current. The shapes of polished rice grains became flat in the #90 program, while grains remained close to the original, spherical shape in the #60 program. The ratios of cracked rice and residual embryos were higher in the #90 program than those in the #60 program. The rice protein content was lower in the #90 program than that in the #60 program. The contents of crude fat, Na, Mg, P and Ca decreased rapidly until rice polishing ratio of 80% in both programs, but the degree of decrease differed between the two programs. The contents of crude fat, Na, Mg, P and Ca were higher in the #90 program than that in the #60 program until the 70% polishing ratio. The water absorption ratio and the ratio of cracked rice during steeping at early stages were higher in the #90 program than that in the #60 program. The enzyme digestibility (Brix) was slightly higher in the #90 program than that in the #60 program; the contents of amino acids in digested solutions were lower and the contents of mineral contents in digested solutions were higher in the #90 program than in the #60 program. The data from the 70% polishing rice analyzed by the national standard methods of rice used for sake making correlated significantly with the data from various rice-polishing ratios. This result indicated that the data from 70% polishing rice analyzed by the national standard methods of rice used for sake making are useful to evaluate the rice properties, even in the case of a lower rice-polishing ratios.

Source

J. Brew. Soc. Japan, 118(5), 340-364 (2023)

4.Targeted mutations produce divergent characteristics in pedigreed sake yeast strains

Author

KLINKAEWBOONWONG Norapat, OHNUKI Shinsuke, CHADANI Tomoya, NISHIDA Ikuhisa, USHIYAMA Yuto, TOMIYAMA Saki, ISOGAI Atsuko, GOSHIMA Tetsuya, GHANEGOLMOHAMMADI Farzan, NISHI Tomoyuki, KITAMOTO Katsuhiko, AKAO Takeshi, HIRATA Dai, and OHYA Yoshikazu

Abstract

Modification of the genetic background and, in some cases, the introduction of targeted mutations can play a critical role in producing trait characteristics during the breeding of crops, livestock, and microorganisms. However, the question of how similar trait characteristics emerge when the same target mutation is introduced into different genetic backgrounds is unclear. In a previous study, we performed genome editing of AWA1, CAR1, MDE1, and FAS2 on the standard sake yeast strain Kyokai No. 7 to breed a sake yeast with multiple excellent brewing characteristics. By introducing the same targeted mutations into other pedigreed sake yeast strains, such as Kyokai strains No. 6, No. 9, and No. 10, we were able to create sake yeasts with the same excellent brewing characteristics. However, we found that other components of sake made by the genome-edited yeast strains did not change in the exact same way. For example, amino acid and isobutanol contents differed among the strain backgrounds. We also showed that changes in yeast cell morphology induced by the targeted mutations also differed depending on the strain backgrounds. The number of commonly changed morphological parameters was limited. Thus, divergent characteristics were produced by the targeted mutations in pedigreed sake yeast strains, suggesting a breeding strategy to generate a variety of sake yeasts with excellent brewing characteristics.

Source

Microorganisms, 11(5), 1274 (2023)

5.Yeast diversity during the spontaneous fermentation of wine with only the microbiota on grapes cultivated in Japan

Author

SHIMIZU Hideaki, KAMADA Aya, KOYAMA Kazuya, IWASHITA Kazuhiro, and GOTO-YAMAMOTO Nami

Abstract

Making wine via spontaneous fermentation without sulfur dioxide and commercial yeast (spontaneous winemaking) is increasing in recent year, but there is scant research regarding microbial communities present in Japan during spontaneous winemaking using culture-independent molecular methods. We analyzed fungal communities and populations during laboratory-scale spontaneous winemaking using sterilized labware to avoid winery-resident microbes. In the spontaneous fermentation of four grape varieties (Pinot Noir, Riesling, Koshu, and Koshusanjaku) grown in the same Japanese vineyard, our analysis of yeast and other fungal species by next-generation sequencing based on the ITS1 region demonstrated that S. cerevisiae was eventually dominant in seven of 12 fermentation batches (three replications for each grape variety), whereas non-Saccharomyces species (e.g., Schizosaccharomyces japonicus, Lachancea dasiensis,and Hanseniaspora valbyensis) became dominant in four batches at the end of fermentation. In another batch, lactic acid bacteria (LAB) became dominant and the fermentation remained incomplete. Diverse microbes were involved in the spontaneous fermentation (particularly in Koshusanjaku), indicating that residual sugar remained and lactic and acetic acid largely increased. Compared to the control wine made with SO₂ and commercial yeast, the concentration of lactic acid was 45-fold higher in the must dominated by L. dasiensis,and the concentrations of acetic acid and lactic acid were 10-fold and 19-fold higher in the must dominated by LAB, respectively. Even when indigenous S. cerevisiae became dominant, the finished wines obtained high sensory-analysis scores for 'complexity' but low scores for 'varietal typicality', indicating the risk of fermentation with unselected wild yeast on the grapes grown in Japan.

Source

Journal of Bioscience and Bioengineering, 136(1), 35-43 (2023)

6.Effects of temperature conditions after rice heading on the brewing properties for the 2002–2019 crop years.

Author

TAKAHASHI Kei, OKUDA Masaki, JOYO Midori, NUMATA Mineyo, BAO Hong-Bin, and KOHNO Hiromi

Abstract

The correlation between the brewing properties of sake rice and temperature for a month after heading remains unclear. In this study, we investigated the relationship between the brewing properties of 22 rice varieties using sequential earlier-period rice analysis data gathered from the 2002 to 2019 crop years and temperature during the rice development period from the Automated Meteorological Data Acquisition System. The 1,000-grain weight of brown rice showed a negative correlation with both the minimum and maximum temperatures for a month after heading. The influence of the minimum temperature was strong in table rice, whereas that of the average and maximum temperatures was strong in rice cultivars for sake brewing. The influence of temperature in the middle to later stages of a month of rice development was larger. Water absorption during the 20 and 120 min period showed a positive correlation with the maximum temperature. The crude protein content of many rice varieties, which is positively correlated with the minimum temperature, is affected by nighttime temperature in the paddy field. As formol nitrogen (FN) is affected by both the crude protein content and Brix value, the influence of temperature was offset. The ratio of Brix to FN showed a negative correlation with both the minimum and maximum temperatures for a month of rice development. Thus, we revealed the correlation between the brewing properties of sake rice and the temperature conditions for a month of rice development.

Source

J. Brew. Soc. Japan、118(7)、503-518 (2023)

7.The relationship between glucose concentrations and overall ratings of sakes at the first-stage sensory evaluations of the annual Japan sake contests

Author

FUJITA Akiko, AKAMATSU Fumikazu, and YAMADA Osamu

Abstract

In order to investigate the relationship between the glucose concentrations and the overall ratings of sakes at the first-stage sensory evaluations of the Annual Japan Sake Contests, statistical analysis was performed using the chemical components and sensory evaluation results of 2,567 ginjo-shu entries from the past 3 years. Our results showed that glucose concentrations and the differences in the glucose concentrations between sequential sake samples did not significantly affect the overall rating. Sake that was rated highly in the required evaluation criteria of “gorgeous aromas” and “refreshing aftertaste” was also rated highly in the “overall rating” by the judging panel. Sake having off-odor indicators of the optional criteria, such as “sulfide” and “moldy”, lowered their “overall rating” considerably. Our results suggest that the judging panel at the first-stage sensory evaluation of the Annual Japan Sake Contests evaluates each sake seriously and conducts separate sensory evaluations without any dependence on specific components according to the judging criteria of flavor harmony and character. Moreover, quality control to eliminate the generation of off-odors along with manufacturing technology to increase the harmony of flavors during sake production are essential to achieve high product ratings.

Source

J. Brew. Soc. Japan, 118(8), 579-587 (2023)

8.The selection of reference standards and creation of the flavor wheel for establishing a sensory analysis of Honkaku shochu and Awamori

Author

OSAFUNE Yukio, TOSHIDA Kenji, HAN Jinshun, ISOGAI Atsuko, and MUKAI Nobuhiko

Abstract

The arrangement of aroma compounds and flavor terminology is an important step in establishing a sensory evaluation system. We have reported on the detection thresholds and the odor activity values of the compounds contributing to the aroma characteristics of Honkaku shochu and Awamori. As a result, thirty-two compounds have been selected as candidates for reference standards. In this work, these compounds were evaluated by experts on Honkaku shochu and Awamori to test the validity of the concentrations and the sensory attribute terms. As a result, it is suggested that candidates are utilizable as reference standards, after increasing the concentrations of some compounds and changing the submission methods. We reviewed the compounds which have very similar aroma characteristic, and finally thirty compounds were adopted as reference standards. Further, a flavor wheel of Honkaku shochu and Awamori was made with reference to the sensory attribute terms which were collected in this work.

Source

J. Brew. Soc. Japan、118(8)、588-599 (2023)

9.Effects of Saccharomyces cerevisiae on oak chips on wine-making and fungi communities in uninoculated-fermentation

Author

SHIMIZU Hideaki, KAMADA Aya, KOYAMA Kazuya, IWASHITA Kazuhiro, and GOTO-YAMAMOTO Nami

Abstract

When uninoculated fermentation is used to make wine, Saccharomyces cerevisiae living on winery equipment and in the vineyards exert important influences on the fermentation. It has been unclear whether yeasts remain after the oak barrel is washed and uninoculated wine fermentation restarted. We prepared oak chips that were immersed in a fermentation mash with S. cerevisiae and (1) washed with water at an ambient temperature, washed with and soaked in (2) water at 80°C, (3) 50 mg/L sulfur dioxide solution, or (4) 30% ethanol solution. We then performed a fermentation test using sterilized grape juice and treated oak chips without yeast inoculation. Fermentation occurred except with the 80°C-treated chips. We next conducted an uninoculated fermentation test using fresh Chardonnay grape juice with or without oak chips that were washed with water after fermentation: S. cerevisiae and Hanseniaspora uvarum increased and finally reached the same percentages as those in a fungal species analysis using high-throughput DNA sequencing. After the fermentation of Chardonnay grapes, many ovoidal and lemon-shaped cells were observed on the oak chip surfaces. Our results thus demonstrated that wood surfaces such as oak chips provide an environment where yeasts can survive, and wood-resident yeasts can re-drive wine fermentation.

Source

J. Brew. Soc. Japan, 118(9), 639-648 (2023)

10.Influence of storage temperature on changes in sake quality

Author

ISOGAI Atsuko, IKEDA Yuriko, KUSAKA Kazutaka, MUKAI Nobuhiko, HISHINUMA Hayato, and UEHARA Hiroshi

Abstract

We investigated changes in the quality of sake stored at 0–35℃ for up to 6 months. Sake stored at 35℃ showed significantly high hineka intensity and a poor overall score, while no significant difference was observed between 15℃ and 0℃. DMTS and methional concentrations increased remarkably at 35℃ and were highly correlated with hineka intensity. Comparing average concentrations before and after 6 months of storage, differences were within 10% at 0℃, at 25℃ methional had almost doubled, and at 35℃ DMTS increased over 10 times. These results indicate that the favorable sake storage temperature is below 15℃ for quality preservation.

Source

J. Brew. Soc. Japan, 118(9), 649-657 (2023)

11.The bio3 mutation in sake yeast leads to changes in organic acid profiles and ester levels but not ethanol production

Author

AKASE Shiori, TOMONAGA Kazuko, TANAKA Jumpei, MORIYA Chise, KIYOSHI Keiji, AKAO Takeshi, WATANABE Kota, KADOKURA Toshimori, and NAKAYAMA Shunichi

Abstract

Biotin is an essential coenzyme that is bound to carboxylases and participates in fatty acid synthesis. The fact that sake yeast exhibit biotin prototrophy while almost all other Saccharomyces cerevisiae strains exhibit biotin auxotrophy, implies that biotin prototrophy is an important factor in sake brewing. In this study, we inserted a stop codon into the biotin biosynthetic BIO3 gene (cording for 7,8-diamino-pelargonic acid aminotransferase) of a haploid sake yeast strain using the marker-removable plasmid pAUR135 and investigated the fermentation profile of the resulting bio3 mutant. Ethanol production was not altered when the bio3 mutant was cultured in Yeast Malt (YM) medium containing 10% glucose at 15°C and 30°C. Interestingly, ethanol production was also not changed during the sake brewing process. On the other hand, the levels of organic acids in the bio3 mutant were altered after culturing in YM medium and during sake brewing. In addition, ethyl hexanoate and isoamyl acetate levels decreased in the bio3 mutant during sake brewing. Metabolome analysis revealed that the decreased levels of fatty acids in the bio3 mutant were attributed to the decreased levels of ethyl hexanoate. Further, the transcription level of genes related to the synthesis of ethyl hexanoate and isoamyl acetate were significantly reduced. The findings indicated that although the decrease in biotin biosynthesis did not affect ethanol production, it did affect the synthesis of components such as organic acids and aromatic compounds. Biotin biosynthesis ability is thus a key factor in sake brewing.

Source

Journal of Biosciences and Bioengineering, 136 (1) 44–50 (2023)

12.The effect of Aspergillus luchuensis pectin methylesterase genes pmeA and pmeB on methanol production in sweet potato shochu

Author

MIZUTANI Osamu, KAKIZONO Dararat, TAKAHASHI Toru, MUKAI Nobuhiko, FUKUDA Hisashi, and YAMADA Osamu

Abstract

To reduce the methanol content in sweet potato shochu, we studied the pectin methylesterase genes of the shochu–koji mold Aspergillus luchuensis. We found the following three homologs of pectin methyleseterase in the genome of A. luchuensis: pmeA, pmeB, and pmeC. Using pectin as a substrate, the methanol-producing activity of the recombinant of each gene expressed in A. luchuensis was examined and found to be present in recombinant PmeA and PmeB. Additionally, small-scale fermentation of sweet potato shochu using disruptions of pmeA and pmeA-pmeB in A. luchuensis (∆pmeA and ∆pmeApmeB) resulted in significant reduction of the methanol content. Taken together, we revealed that the A. luchuensis pmeA gene was mainly involved in methanol production in sweet potato shochu.

Source

Bioscience, Biotechnology, and Biochemistry, 87(7), 777-785 (2023)

13.Analysis of sake components presented to the Japan Sake Awards 2022

Author

YAMADA Osamu, ISOGAI Atsuko, FUJITA Akiko, KISHIMOTO Toru, AKAMATSU Fumikazu, BOERZHIJIN Surina, NISHIMOTO Masaki, KANDA Ryoko, TERAMOTO Satoko, OGUSHI Kensuke, and FUKUDA Hisashi

Source

Report of the Research Institute of Brewing, 195, 1-18 (2023)

14.Review of the 45th Honkaku Shochu and Awamori contest in 2022

Author

MUKAI Nobuhiko, ISOGAI Atsuko, OKUDA Masaki, MASAKI Kazuo, TAKAHASHI Kei, OSAFUNE Yukio, BOERZHIJIN Surina, and FUKUDA Hisashi

Source

Report of the Research Institute of Brewing, 195, 19-36 (2023)

15.Analysis of beer components presented to craft beer contest of Japan Brewers Association in 2023

Author

KUSAKA Kazutaka, KISHIMOTO Toru, KAMIMOTO Maki and TERAMOTO Satoko

Source

Report of the Research Institute of Brewing, 195, 37-44 (2023)

16.Survey of ethyl carbamate in long-term aged sake

Author

BOERZHIJIN Surina, ISOGAI Atsuko, and MUKAI Nobuhiko

Source

Report of the Research Institute of Brewing, 195, 45-49 (2023)

17.Characterization of wine and microbial flora in mixed culture withTorulaspora delbrueckii

Author

GOTO-YAMAMOTO Nami, NISHIBORI Nahoko, and TAKAHASHI Masayuki

Abstract

The application of the mixed culture method that uses non-Saccharomyces yeast and Saccharomyces wine yeast in winemaking has been widely reported. However, we found that the fermentation speed was lower when small-scale winemaking was carried out using a mixed culture of Saccharomyces cerevisiae and Torulaspora delbrueckii than when using a pure culture of S. cerevisiae. The low cell density of S. cerevisiae observed in the mixed culture seems to be due to unknown factors and not the inhibition by alcohol or the shortage of assimilable nitrogen. Red wine produced by the mixed culture method has a light red color and a low ratio of stabilized pigments, both of which are probably caused by the low acetaldehyde production by T. delbrueckii. Thus, even though the mixed culture method has several benefits, careful consideration of winemaking methods is necessary for the application of this method.

Source

Journal of ASEV Japan, 34 (1), 3-12 (2023)

18.Carbon stable isotopic compositions of glucose and ethanol in sake after simultaneous saccharification and fermentation processes

Author

AKAMATSU Fumikazu, IGI Yukari, FUJITA Akiko, YAMADA Osamu, and OKUDA Masaki

Abstract

The carbon stable isotopic composition of glucose is transferred to that of ethanol during the simultaneous saccharification and fermentation processes of sake production. However, there is limited information regarding carbon isotope discrimination between the ingredient rice and the sake components. Our fermentation experiments show that the carbon stable isotopic composition of rice is intermediate between those of glucose and ethanol in sake and do not differ significantly from those of rice koji and sake lees. Carbon isotope discriminationfrom rice to ethanol and from glucose to ethanol is 0.9 ± 0.1‰ (mean ± standard deviation, n = 18) and 1.9 ±0.2‰, respectively. This is approximately half of the isotope discrimination observed in grape wine due to the saccharification process during sake manufacture. Carbon isotope discrimination from ingredient rice to sake components provides valuable insights for the manufacturing process and the authentication of sake.

Source

Food Chemistry, 424(1), 136372 (2023)

19.A study on the impact of the introduction of bottled sake and the establishment of the capacity of Shi-gou bottle and 300-mL bottle

Author

WATANABE Yuji and OKADA Kanako

Abstract

Although the Shi-gou（四合）or 720-mL bottle is commonly used as a standard for sake containers, the origin of its capacity is still debated. This article provides an overview of the introduction of glass bottles and the establishment of domestic production systems, the introduction and development process of bottled sake in the sake industry, and their effects. This article conducted inference regarding the factors behind the origin and establishment of the Shi-gou and 300 mL capacities from historical documents. During the Meiji era (1868-1912), glass bottles were introduced, and the empty imported Western liquor bottles were initially used. Domestic production systems began to be established around 1887 (Meiji 20), and mechanization progressed around 1906 (Meiji 39), gradually strengthening production capacity throughout the Taishō era (1912-1926). In the sake industry, the production of bottled products began on a full scale around the end of the Meiji era (1868-1912). During the Taishō period, the market for bottled sake expanded. This resulted in the establishment of “bottle merchants” who collected and sold empty bottles, and a structure for reusing bottles unique to alcoholic beverages and soy sauce. The Shi-gou bottle is inferred to have originated from Western liquor bottles (known as “reputed quart” bottles), which had a standard capacity of about 750 mL, and the 300-mL bottle was introduced in response to the metric system. It is also inferred that this capacity became established as standards due to the coexistence of domestic and foreign bottles and the reuse of bottles by “bottle merchants”.

Source

Journal of sakeology, 2, 1-31 (2023)

20.Effect of water deficit stress during fruit cultivation on the carbon stable isotopes of organic acids in Japanese apricots and liqueur prepared from these fruits

Author

AKAMATSU Fumikazu, JOMURA Noriaki, TSUCHIDA Yasuhisa, IGI Yukari, HISATSUNE Yuri, TERAMOTO Satoko, FUJITA Akiko, and YAMADA Osamu

Abstract

The objective of this study was to assess the impact of water deficit stress during fruit cultivation on the δ¹³C values of citric acid and malic acid in Japanese apricots at different ripeness stages and their resulting liqueurs. Our experiments show that water deficit stress increases the δ¹³C values of citric acid and malic acid in tree-ripened fruits, counteracting the typical decrease during ripening. However, water deficit treatment has a minimal effect on the δ¹³C values of organic acids in green fruits. Regardless of fruit ripeness or water status, the δ¹³C values of organic acids in fruits are directly reflected in the resulting liqueurs. Overall, water deficit stress during fruit cultivation has the potential to promote similarity in the δ¹³C values of organic acids across fruits at different ripeness levels, reducing variations among liqueurs derived from fruits of varying ripeness levels.

Source

Isotopes in Environmental and Health Studies , 60(1), 1-12 (2024)

21.The effect of mash-in temperature on the characteristics and flavor stability of Pilsner-type beer

Author

KISHIMOTO Toru, HISATSUNE Yuri, and YAMADA Osamu

Abstract

Beers were brewed at mash-in temperatures of 35 °C, 50 °C, and 65 °C, and their flavor profiles and stability were examined. Beers with mash-ins at 35 °C and 50 °C exhibited full-bodied taste and estery sensory qualities with higher concentrations of esters and amino acids. Higher extract yields were obtained in wort with mash-ins at 35 °C and 50 °C, the optimal temperatures for enzymes to break down the tissue where starch granules are located. In contrast, the beer with a 65 °C mash-in temperature had a light taste and a toast-like aroma. In terms of providing nutrition for the yeast, the proteolytic process to produce amino acids seemed unnecessary for brewing beer made exclusively from malt. Following a month of storage at 30 °C, cardboard flavors predominated in beers with mash-in temperatures of 35 °C and 50 °C, while honey and sherry-like scents predominated in beers with a mash-in temperature of 65 °C. The concentrations of the 14 components contributing to the stale flavor of Pilsner-type beers, including Strecker aldehydes, did not correlate with mash-in temperature, with the exception of the concentration of (E)-2-nonenal, even though the mash-in temperatures were predicted to affect the formation of Strecker aldehydes during beer storage.

Source

American Society of Brewing Chemists , 82(1), 32-38 (2024)

22.Effects of fermentation nutrients for wine on sake brewing (Part 2)　-Differences due to the timing for adding

Author

IIZUKA Sachiko, TERAMOTO Satoko, FUJITA Akiko, and MUKAI Nobuhiko

Abstract

Previously, we have examined the one-step and the three-step (Stimula Sauvignon Blanc, addition at third step Tome ; Optimum White, addition at the day before pressing) preparations for fermentation mash with the use of fermentation nutrients for wine（Stimula Sauvignon Blanc and Optimum White, Lallemand）, their addition improved the utility efficiency of raw materials and enhanced the aroma of the brewed sake. In this study, we have investigated differences due to the timing for adding by the three-step (addition at koji and water mixture Mizu-koji or first step Soe) preparation for fermentation mash using wine and sake yeasts. In the case of using wine yeast, the effect of Mizu-koji or Soe in the addition of fermentation nutrients Stimula Sauvignon Blanc was higher than Tome in the previous report, while there was hardly any difference in Mizu-koji and Soe. Although this was not as remarkable as the previous results of the one-step preparation for fermentation mash, the addition of Stimula Sauvignon Blanc improved the utility efficiency of raw materials and enhanced the aroma of the brewed sake in the use of wine yeast. It was suggested that its addition improved the fermentative metabolism in sake brewing using wine yeast. The effects of their addition in the case of using sake yeasts were smaller than that of using wine yeast, the same as in the previous report. However little difference was observed in the timing for adding among Mizu-koji, Soe and Tome. From these results, in the case of using wine yeast, adding at the early stage of the sake brewing process is effective at the time for the addition of the fermentation nutrients for wine used in this study. In the case of using sake yeast, the timing for adding fermentation nutrients for wine does not have so great an influence on the quality of the sake.

Source

J. Brew. Soc. Japan119(1), 45-55 (2024)

23.Physiological role of the EHL gene in sake yeast and its effects on quality of sake

Author

TOMONAGA Kazuko, TANAKA Jumpei, KIYOSHI Keiji, AKAO Takeshi, WATANABE Kota, KADOKURA Toshimori, and NAKAYAMA Shunichi

Abstract

The EHL1/2/3 genes were identified by whole-genome sequencing of Kyokai No. 7 (K7), which is a well-known representative Japanese sake yeast Saccharomyces cerevisiae. The genes are present in K7, but not in laboratory strain S288C. Although the genes were presumed to encode epoxide hydrolase based on homology analysis, their effect on cellular metabolism in sake yeast has not yet been clarified. We constructed ehl1/2/3 mutants harboring a stop codon in each gene using the haploid yeast strain H3 as the parental strain, which was derived from K701, and investigated the physiological role and effects of the EHL1/2/3 genes on sake quality. Metabolome analysis and vitamin requirement testing revealed that the EHL1/2/3 genes are partly responsible for the synthesis of pantothenate. For fermentation profiles, ethanol production by the ehl1/2/3 mutant was comparable with that of strain H3, but succinate production was decreased in the ehl1/2/3 mutant compared to strain H3 when cultured in yeast malt (YM) medium containing 10% glucose and during sake brewing. Ethyl hexanoate and isoamyl acetate levels in the ehl1/2/3 mutant strain were decreased compared to those of strain H3 during sake brewing. Thus, the EHL1/2/3 genes did not affect ethanol production but did affect the production of organic acids and aromatic components during sake brewing.

Source

Journal of Biosciences and Bioengineering, 137,195-203 (2024)