Development of a process for producing ethyl caproate‐ and ethyl lactate‐rich rice shochu

To increase the popularity of rice shochu, a process was developed to produce ethyl caproate‐ and ethyl lactate‐rich rice shochu. On a laboratory‐scale, there was a shochu production trial with Saccharomyces cerevisiae Y‐E. Caproic acid added in the second‐stage fermentation was esterified to ethyl caproate. Both ethyl caproate and ethyl lactate were produced by adding a caproic acid‐producing bacterial (CAPB) consortium and lactic acid bacterium (LAB) to the shochu production process. Yellow koji was more appropriate for producing a flavour‐rich shochu with the addition of a CAPB consortium and LAB than white koji. Optimal addition time for the CAPB consortium and LAB was on the first day of the second‐stage fermentation, judging from concentrations of ethyl caproate and ethyl lactate produced. Additional dosages of CAPB consortium and LAB positively affected the formation of ethyl caproate and ethyl lactate, respectively. Shochu production with the addition of 2% and 4% CAPB consortium led to ethyl caproate concentrations of 27.3 mg/L and 47.9 mg/L in genshu, respectively, and the shochu achieved the best sensory test score from the Japanese shochu brewery panellists. Copyright © 2015 The Institute of Brewing & Distilling     

Characteristic odour compounds in shochu derived from rice koji

Shochu, a traditional Japanese distilled liquor, makes use of rice koji, which is koji mould grown on rice grain. Rice koji is an essential ingredient of Japanese liquors such as shochu, and it plays a role as a source of the enzyme to degrade starch. However, there has been no research on the effect of rice koji on the flavour of shochu. Therefore, in this study, the volatile compounds in shochu derived from rice koji were investigated. Two shochu samples were prepared to assess the contribution of rice koji to the flavour. One shochu sample was prepared from rice koji, yeast and water (rice koji‐shochu). The other shochu sample was obtained from steamed rice and various enzymes instead of rice koji (enzyme‐shochu), along with yeast and water. The volatile compounds were analysed by gas chromatography–mass spectrometry (GC‐MS) and GC‐MS/olfactometry with aroma extract dilution analysis. The results showed that enzyme‐shochu had a higher flavour dilution value of dimethyl trisulphide and hexanal, whereas rice koji‐shochu had a higher flavour dilution value of some ester compounds that imparted aromatic odours such as fruity. Some unknown peaks representing compounds that impart characteristic odours such as soda, potato, lavender, and tea‐like were specifically detected in rice koji‐shochu. The concentrations and calculated odour active values of 14 compounds were measured. These results showed that isovaleraldehyde, ethyl caprylate, ethyl caproate and ethyl 2‐methylbutyrate played an important role in imparting the specific odour of rice koji‐shochu. Copyright © 2016 The Institute of Brewing & Distilling     

Behaviour of some volatile compounds during distillation of fermented marc exposed to the smoking process

Fermented marc was exposed to a controlled smoking process for 120, 240 and 460 min before distillation. To improve insight into the behaviour of ethanol and the partitioning of some volatile compounds, each distillate was collected in fractions (ethanol content from 24 to 59% vol) and analysed for the higher alcohols (2‐butanol, n‐butanol, n‐propanol, isoamyl alcohols, n‐hexanol) ethyl esters (ethyl acetate, ethyl lactate, ethyl caproate, ethyl caprylate, ethyl caprate, ethyl myristate and ethyl laurate) and volatile phenols (guaiacol, methyl guaiacol, ethyl guaiacol, propyl guaiacol, eugenol and isoeugenol). The results obtained showed that the behaviour of ethanol was not regular and the alcohol strength was lower when the smoking process was applied to fermented marc. The volatile phenols highlighted a distillation behaviour characterised by an increase in concentration at the end of the distillation process when ethanol decreased. Long time exposure of the marc to the smoking process resulted in higher reduction of ethanol, higher alcohols and ethyl esters. Instead, the volatile phenols increased with the duration of the smoking process.     

SEMICONTINUOUS ETHANOL FERMENTATION WITH SHOCHU DISTILLERY WASTE*

An effective utilization system using distillery waste discharged from Japanese traditional shochu factory was developed. Mugi (barley) shochu distillery waste discharged from a novel vacuum distillation procedure (35–40°C) contained a large number of viable yeast (7 × 10⁶ cells/ml), glucoamylase activity (19.7 units/ml), acid protease activity (940 units/ml), and neutral protease activity (420 units/ml). Ethanol fermentation was achieved with a mash composed of glucose as the sola carbon source and mugi shochu distillery waste. After ethanol fermentation was completed the fermented broth was again distilled at 35–40°C in vacuo and the non volatile residue used in the next ethanol fermentation. In this way, semicontinuous ethanol fermentation system of more than 10 cycles was developed. Even in the distillate of the mash of the 8th fermentation cycle, 7.9% of ethanol, 33.0 ppm of ethyl acetate, 28.5 ppm of isobutyl alcohol, and other aromatic compounds were present. A semicontinuous ethanol fermentation system has been developed for shochu distillery waste which conventionally is treated as wastewater.     

Effect of the FAA1 gene disruption of sake yeast on the accumulation of ethyl caproate in sake mash

Fatty acid activation gene (FAA1) in sake yeast Kyokai no. 701 (K701) was disrupted to investigate the accumulation of ethyl caproate in sake mash. Ethyl caproate, recognized as an important apple-like flavor in sake, is generated by fatty acid synthesis in yeast cells. The disruptant for the FAA1 gene (K701Δfaa1) exhibited a reduced growth rate in a medium containing cerulenin and myristic acid or oleic acid compared with that of the parental strain (K701). In a sake brewing test in which the rice used was polished to 60% of its original size, the fermentation ability of K701Δfaa1 was inferior to that of K701 but the production of ethyl caproate by K701Δfaa1 was 1.6-fold higher than that by K701. These results suggest that the FAA1 gene in sake yeast plays an important role in sake brewing and the accumulation of ethyl caproate.     

Development of Efficient Shochu Production Technology with Long‐term Repetition of Sashimoto and Reuse of Stillage for Fermentation

In traditional shochu production with a long‐term repetition of sashimoto, the activity of yeast cells decreases, generally resulting in bacterial contamination problems. In this study, a pilot scale study was carried out to demonstrate a technique developed with a laboratory scale test, which improved the activity of the yeast in the first‐stage fermentation and the possibility of reuse of stillage for the fermentation to reduce the quantity of stillage from the distillation by 50%. The yeast cells were activated by aeration and stirring for several hours after sashimoto. The yeast cells maintained a high activity level during the entire test period. The ethanol concentration of the second‐stage fermented mash was improved and an ethanol concentration of more than 17.5% (v/v) was achieved when stillage was reused in place of water for the fermentation. Comparing the flavour compounds of shochu produced by the traditional process with the long‐term repetition of sashimoto, 0.2 ppm of furfural was detected in the shochu produced from the stillage reuse process. No other significant differences were found in the concentrations of the low‐, middle‐ and high‐boiling flavour compounds examined, nor in the concentrations of isoamyl acetate and β‐phenethyl acetate, which are desired flavour compounds in shochu.     

Classification of Barley Shochu Samples Produced Using Submerged Culture and Solid‐state Culture of Koji Mold by Solid‐phase Microextraction and Gas Chromatography‐Mass Spectrometry

An easy and fast method of analyzing volatile components contained in shochu, by headspace solid‐phase microextraction and gas chromatography‐mass spectrometry, was established to determine the difference in the content of the various components of barley shochu produced using a submerged culture of koji mold (submerged‐culture shochu) and a solid‐state culture of koji mold (solid‐culture shochu). The contents of the volatile components between the two types of shochu were compared. The results of the comparison revealed that the content of ethyl lactate, ethyl benzoate, 3‐methyl‐1‐pentanol, diethyl succinate, citronellol, and 2‐phenethyl acetate differed between the submerged‐culture and the solid‐culture shochu samples. In addition, the classification of barley shochu samples, including those on the market, into submerged‐culture shochu and solid‐culture shochu, was carried out by multivariate analysis using the quantitative values of the above‐mentioned six compounds, and distinct discrimination was found possible.     

PRODUCTION OF SHOCHU ON A COMMERCIAL SCALE FROM POST-DISTILLATION SLURRY BY A NEWLY DEVELOPED RECYCLING PROCESS

During commercial scale fermentation for the production of rice shochu using post-distillation slurry in place of the first-stage mash, it was difficult to stir the mash from the first to the third day because of the high viscosity of the mash. Shochu was therefore fermented with a two-step addition of cooked rice, adding rice on the first and third days, to reduce the viscosity of mash during the first few days. Even though the ethanol concentration of the mash after 9 d was 17.2 v/v% and was a little lower than that obtained in laboratory scale tests, the yield of pure ethanol was 473 ml kg^?1 of rice and this value was higher than the average value (450 ml kg^?1) when shochu is made in the standard manner on a commercial scale. The shochu produced on a commercial scale by the newly developed recycling process was very mild and smooth, and received high scores in sensory tests.     

ETHANOL FERMENTATION WITH SHOCHU DISTILLERY WASTE AND AROMATIC RED RICE BRAN

Shochu distillery waste which had been exhausted by a vacuum-distillation procedure at low temperature (35–40°C) was used for secondary ethanol fermentation with the bran of aromatic red rice (Oryza sativa var. Indica, Tapol). The filtrate of the fermented mash made from kome shochu distillery waste and aromatic red rice bran had a characteristic wine-like red color, contained about 12% ethanol (v/v), and possessed a fine aroma that was fortified with the aromas of higher alcohols and volatile esters during secondary ethanol fermentation. A novel red alcoholic beverage was produced from the industrial by-product of shochu-making, kome shochu distillery waste and a by-product of Sekihan-cooking, aromatic red rice bran. The filtrate of the fermented mash had a characteristic absorbance at 530 nm. As the amounts of aromatic red rice bran in the mash were increased, the absorbance at 530 nm increased. Thus, a novel system utilizing shochu distillery waste, which is conventionally treated as wastewater, and aromatic red rice bran was established economically using a simple vacuum-distillation and secondary ethanol-fermentation procedure without the need for any complicated or expensive processes.     

红曲霉Monascus sanguineus X1处理黄水的培养基优化及酯化液制备

黄水是白酒酿造的主要副产物之一,富含多种有机质,可用于制备酯化液促进白酒增香,提高其利用率。研究了一株高产酯化酶的红曲霉菌株Monascus sanguineus X1,以酯化酶活力为指标,从碳源、碳氮比、接种量和pH值4个方面对X1菌株的培养基进行单因素实验及正交试验优化;采用酯化酶液处理黄水,制备酯化液,研究了黄水、乙醇、己酸等酯化前体物质添加量对酯化液制备的影响。结果表明,该红曲霉优化发酵培养基组分(以100 mL计):大米粉7.0 g,大豆蛋白胨2.0 g,NaNO30.2 g,KH2PO40.15 g,MgSO4·7H2O 0.1 g,培养基初始pH值5.0,接种量10%(体积分数)。在此条件下,添加体积分数为10%的黄水和体积分数为4%的乙醇,酶活力可达745.80 U/mL。向酯化酶液中加入体积分数为0.8%的己酸和体积分数为20%的乙醇继续培养1 d后,酯化液中己酸乙酯的体积分数可达0.121%;而向酯化酶液中补加体积分数为10%的黄水后,己酸乙酯和乳酸乙酯的体积分数分别可达0.055%和0.032%。该结果旨在为将黄水资源用于白酒增香提供理论参考。     

酿酒酵母Y3401产己酸乙酯发酵条件的优化

以酿酒酵母Y3401为研究对象,对该菌株发酵产己酸乙酯条件进行优化。首先,通过单因素对其培养基条件(pH值和糖度)及诱导条件(温度、转速、接种量、乙醇添加量、己酸添加量、前体添加时机和诱导时间)进行优化,然后通过Plackett-Burman试验,筛选出5个显著影响酿酒酵母Y3401产己酸乙酯的因素,再通过最陡爬坡试验确定最大响应区域,最后采用Box-Behnken试验设计及响应面分析,确定其最优产己酸乙酯条件为:糖度14 Brix、初始pH 7、温度25℃、转速180 r/min、接种量3.5%、乙醇添加量8%、己酸添加量0.059%、前体添加时机30 h、诱导时间31 h。在此培养条件下己酸乙酯产量达10.1 mg/L。本研究结果有助于酿酒酵母Y3401更好地应用于白酒发酵中。     

Determination of Selected Beer Flavours: Comparison of a Stir Bar Sorptive Extraction and a Steam Distillation Procedure

The aim of this work was focused on the comparison of two sample preparation procedures — a stir bar sorptive extraction (SBSE) followed by solvent back extraction and a well‐established distillation method followed by liquid/liquid extraction — for the simultaneous determination of some beer esters (isoamyl acetate, ethyl caproate, ethyl caprylate, ethyl caprate, phenyl‐ethyl acetate, ethyl laurate, ethyl myristate, ethyl palmitate) and free fatty acids (caproic, caprylic, pelargonic, capric). Subsequent gas chromatographic analyses with flame ionization detection were used for the determination of these compounds. Both procedures were characterized by good linearity (correlation coefficients were higher than 0.9987). The relative standard deviations were found to be 2.1–7.3% for SBSE and 10–14% for the distillation technique with recovery 81–107% and 70–89%, respectively. Results obtained by these two procedures were in good correlation.     

浓香型白酒酒醅中乳酸菌分离及其对模拟固态发酵的影响

从发酵酒醅中分离得到21株产乳酸菌株,其中16株为芽孢杆菌。利用梅里埃微生物鉴定仪鉴定,得到干燥棒杆菌（Corynebacterium xerosis）、耳葡萄球菌（Staphylococcus auricularis）、枯草芽孢杆菌（Bacillussubtilis）、巨大芽孢杆菌（Bacillus megaterium）、腊状芽孢杆菌（Bacillus cereus group）、浸麻芽孢杆菌（Paenibacillusmacerans）6种产乳酸菌。将6株产酸菌进行模拟固态发酵,结果显示所有乳酸菌都不同程度的抑制了己酸、己酸乙酯以及乳酸乙酯的产量,其中浸麻芽孢杆菌、巨大芽孢杆菌属的2株产乳酸菌严重抑制了乙醇和己酸乙酯的生成量,巨大芽孢杆菌的一株还严重抑制了己酸的产量。     

Effects of the cultivation period of sweet potato on the sensory quality of imo‐shochu,a Japanese traditional spirit

Imo‐shochu is a Japanese traditional spirit made from sweet potatoes. Characteristic volatile compounds in imo‐shochu are mainly derived from the sweet potato and its flavour significantly depends on the quality and cultivar of sweet potato used. Thus, the effects of the cultivation period of sweet potatoes on sensory characteristics and composition of volatile compounds of imo‐shochu were investigated. Sweet potatoes (cv. Koganesengan) used in this study were harvested at 120, 150 or 180 days after planting, and each sample was used to prepare imo‐shochu. The imo‐shochu samples were evaluated by eight panellists in a blind study, who ranked them on the basis of various odour and taste attributes. Rank sums were calculated and data were analysed using the Friedman test. The compositions of the volatile compounds in the imo‐shochu samples were analysed using gas chromatography–mass spectrometry (GC‐MS). Sensory evaluations showed that a longer cultivation period of the sweet potatoes enhanced the floral aroma and characteristic taste of imo‐shochu. In addition, imo‐shochu prepared with the sample cultivated for 150 days was evaluated to have a sweeter taste than that prepared with the other samples. The GC‐MS analysis showed that imo‐shochu prepared with the sample cultivated for 180 days contained a lower concentration of monoterpene alcohols, but higher concentrations of β‐damascenone, rose oxide, and fatty acid esters than the imo‐shochu prepared with the sample cultivated for 120 days. These differences in the composition of the volatile compounds affected the sensory qualities of the imo‐shochu. Copyright © 2016 The Institute of Brewing & Distilling     

试论红曲霉在传统白酒中的生产与应用

在传统白酒中,以己酸乙酯为主的酯类成分,对酒质的等级有较为明显的影响.相比于目前广泛使用的乙酸菌、红曲霉菌可以促使己酸、乙醇进行酯化反应,生成己酸乙酯,因此对白酒提质有良好效果.从斜面培养、扩大培养等方面,介绍了制作红曲霉的工艺流程,随后采用对比法,分析了红曲霉菌对于基酒中总酸、总酯、出酒率以及己酸乙酯、乙酸乙酯等各类...     

保持低度浓香型白酒质量稳定技术的研究

在低度浓香型白酒勾兑过程中,通过有针对性的选择使用己酸含量较大的调味酒,适当提高己酸含量,能有效地抑制、延缓己酸乙酯的水解,达到稳定低度浓香型白酒酒质、延长其货架期的目的.     

化学酯化法对酒尾和黄水的利用

试验以浓香型白酒生产过程中的副产物-酒尾、黄水为主要原料,采用化学酯化法制备酯化反应产物,研究正己酸添加量、乙酸添加量、反应时间及反应温度对酯化反应产物中总酯含量的影响,并通正交试验优化酯化产物制备参数,使所得产物中香味物质含量高,比例适宜,风味协调.     

Chemical and microbiological quality of sugar cane juice influences the concentration of ethyl carbamate and volatile congeners in cachaça

The aim of this study was to assess the influence of heat treatment of sugar cane juice, supplementation with urea and double distillation on the concentration of volatile congeners (acetic aldehyde, ethyl acetate, n‐propyl, isobutyl and isoamyl alcohols and acetic acid) and contaminants (methanol, 1‐propyl and 2‐butyl alcohols, copper, and ethyl carbamate) in cachaça. Samples of fresh sugar cane juice, sugar cane juice submitted to heat treatment and contaminated sugar cane juice were supplemented (or not) with urea and fermented. The washes so obtained underwent single and double distillation. Supplementation with urea stimulated ethyl carbamate formation. The distilled products that originated from contaminated worts presented higher concentration of acetic acid and ethyl carbamate. Double distillation reduced the concentration of contaminants. The best quality pot still cachaça was obtained employing heat treatment of sugar cane juice, nonsupplementation with urea and double distillation. Copyright © 2015 The Institute of Brewing & Distilling     

Isolation and Characterization of Shochu Yeasts with Superior Brewing Ability from Shochu Mashes

Seven yeasts with superior ability in terms of alcohol fermentation and aromatic ingredient generation were isolated from 272 wild yeasts obtained from shochu mashes of shochu breweries. These seven yeasts were examined for their fermentation ability with rice and sweet potato using small scale of fermentation tests. Moreover, their thermotolerance was evaluated by growth tests and fermentation tests with barley koji. Among the isolated seven yeasts, the shochu yeast “MF062” was superior in the characteristics of fast fermentation, high alcohol production, aromatic ingredient generation and thermotolerance. It was named the “Heisei Miyazaki Yeast”. From the results of analyses of physiological and genetic characteristics of MF062, it was shown to be a Saccharomyces cerevisiae, but it showed different characteristics from the industrial yeasts used in shochu production. Using a sweet potato shochu brewing test, with 60 kg of raw materials and yeast MF062, it was confirmed that a high alcohol production yield and a high quality shochu could be obtained.