Higher alcohols concentration and its relation with the biological aging evolution

The production of 1-propanol, isobutanol, 2-methyl-1-butanol, 3-methyl-1-butanol and 2-phenylethanol by two flor yeast strains during accelerated biological aging of sherry wines with different aging time has been evaluated. The S. cerevisiae G1 strain has shown a higher production of higher alcohols than the S. bayanus F12 strain highlighting the 1-propanol production in the youngest wine. Differences between the two studied yeasts decreased in relation with the aging time of the initial wine used. The multiple regression analysis carried out to relate the higher alcohols concentration and the values obtained from an aging equation showed R-squared values ranging from 81.1 to 96.5%. The higher alcohols that best described such relation were 1-propanol, isobutanol and 3-methyl-1-butanol.     

无水有机醇介质中盐酸对蜡质玉米淀粉性质的影响

以无水甲醇、无水乙醇、异丙醇及正丁醇作溶剂,用盐酸对蜡质玉米淀粉进行改性。研究了蜡质玉米淀粉在有机醇溶液中酸改性前后的物化性质。结果表明经酸处理的蜡质玉米淀粉随有机醇介质(从甲醇到正丁醇)碳原子数量的增加,颗粒表面逐步出现小孔直到产生裂纹,冻融稳定性依次减弱,溶解度逐渐增大,膨胀度逐渐降低;淀粉的晶型基本没有变化,但对应衍射峰强度减弱。以上结果表明酸在不同有机醇介质中对淀粉的作用程度不同,从甲醇到丁醇依次增强。     

Major congeners of australian and imported brandies and other spirits as indicators of authenticity

The quantitative determination of the congeners methanol, n-propanol, ethyl acetate, i-butanol (2-methyl-1-propanol) and amyl alcohols (2-methyl-1-butanol and 3-methyl-1-butanol, which were not separated), was carried out on 61 Australian brandies, 61 French brandies and 50 wine distillates by gas chromatography. A comparison of the absolute amounts of congeners and their ratios (in the case of the C₃–C₅ alcohols) is presented in the light of several criteria of authenticity proposed by previous workers. Of these criteria, it was found that the amyl/i-butyl alcohol ratio and the i-butyl/n-propyl alcohol ratio were the most useful—on this basis, 11 French brandies (but no Australian brandy) were considered to be of suspect authenticity.     

Major constituents of fusel oils distilled from Australian grape wines

Fusel oils from Australian grape wines (Vine sp. Vitis vinifera) have been found to consist substantially of ethanol, n-propanol, isobutanol (2-methyl-1-propanol), isoamyl alcohol (3-methyl-1-butanol) and active amyl alcohol (2-methyl-1-butanol). In addition there are present large numbers of aliphatic esters, believed to be of considerable importance to grape brandy and spirit flavour and quality. The quantities and occurrence of these esters have been found to follow a systematic pattern. The major esterified alcohols are related to the free alcohols present and the major esterified acids occur as a series of acids of even carbon number with a maximum concentration at the n-decanoic acid. These relationships provide a basis for calculating the approximate ester composition of fusel oil.     

Synthesis of higher alcohols during cider processing

Ciders from two apple cultivars Gloster and Gala, were prepared. Apples were crushed and juice was extracted, immediately after crushing or after 24 h of maceration. Juice was allowed to ferment at 15°C and analysed for higher alcohols and sugars during fermentation. All higher alcohols analysed increased during fermentation as a result of yeast activity. More higher alcohols were synthesised in cider made from Gala cultivar than in cider from Gloster cultivar. Maceration increased the synthesis of iso-amyl alcohol, 2-phenyl ethanol, n-propanol, n-butanol, iso-butanol and methanol. Sensory evaluation classified cider made from non-macerated Gloster cultivar as the best followed by non-macerated Gala cultivar and macerated Gala cultivar. Sensory evaluation score correlated negatively to the sum of higher alcohols.     

Characterisation of Chinese alcoholic beverages by their congener contents

Using gas-liquid chromatography 33 Chinese alcoholic beverages were analysed for their contents of methanol, ethyl acetate, n-propanol, iso-butanol and iso-amyl alcohol (sum of 3-methyl-1-butanol and 2-methyl-1-butanol). A characteristic pattern of the ratios of some of the major congeners was observed. This was compared with the corresponding results for other alcoholic beverages obtained by the authors and by other workers. It was found that the ratios of iso-butanol: n-propanol, iso-amyl alcohol: n-propanol and methanol: n-propanol are useful criteria for the identification of Chinese alcoholic beverages.     

Dispersion of food proteins in water-alcohol mixed dispersants

Dispersions of commercial casein and whey protein and laboratory-prepared soybean protein were studied in mixed dispersants of water with various aliphatic alcohols, methanol, ethanol, n-propanol and 2-propanol. Supernatant and protein sediments were separated by centrifugation in two steps: 1800 rpm 10 min, followed by centrifugation of the supernatant at 50 000 rpm for 60 min (125 000×g). A gel-like protein sediment obtained at low alcohol concentration by high-g centrifugation increased in amounts as a function of the alcohol concentration until it progressively transformed, with higher alcohol concentrations, into an opaque flock (precipitate), sedimenting at 1800 rpm. It was concluded that the sediment obtained by ultracentrifugation was a protein of increased density which was produced by partial and progressive dehydration and alcohol binding. The conversion of the sediment into a flock or precipitate is discussed in terms of the hydrophilic-lipophilic balance of the protein and of the polar-nonpolar character of the dispersant.     

Thermostable NAD+-dependent (R)-specific secondary alcohol dehydrogenase from cholesterol-utilizing Burkholderia sp. AIU 652

An alcohol dehydrogenase produced by Burkholderia sp. AIU 652, which was isolated with a cholesterol medium, was purified to homogeneity and characterized. The enzyme had broad substrate specificity, and the best reaction was the reversible oxidation of 2-propanol to acetone and 2-butanol to 2-butanone. The K(m) values for secondary alcohols and ketones were much lower than those for primary alcohols or diols. In addition, the enzyme oxidized R-(-)-alcohols in preference to S-(+)-alcohols, and utilized NAD+, but not NADP+ as the cofactor. The molecular mass was 150 kDa with four identical subunits, and the activity was inhibited by o-phenanthroline, 8-hydroxyquinoline, and alpha,alpha'-dipyridyl. Thus, this enzyme was classified into a group of NAD+-dependent R-(-)-specific secondary alcohol dehydrogenases. However, this enzyme was better than the previously reported NAD+-dependent R-(-)-specific secondary alcohol dehydrogenases for chiral chemical synthesis in terms of substrate specificity, stereospecificity, and thermostability. This enzyme might be applicable as an effective biocatalyst for the production of chiral alcohols and related compounds.     

静态顶空气质联用法测定霞多丽在酒精发酵过程中香气的变化

运用静态顶空-气相色谱质谱联用法,从霞多丽葡萄汁到酒精发酵结束,每隔12h对其香气成分进行检测。检测得到的香气成分通过质谱谱库进行定性,色谱峰面积归一化法进行定量。测定结果显示:霞多丽在酒精发酵过程中共检测出31中香气物质,其中醇类物质有11种,酯类物质有13种,其他物质(酸、醛、酮)有7种。发酵前后香气成分的种类和相对含量变化显著。其中酯类和醇类物质的种类和相对含量随着发酵的进行有所增加,而其他类(酸、醛、酮)物质的种类和相对含量随着发酵的进行急剧下降。发酵结束后,发酵液的主要香气成分为:乙醇、2-甲基丙醇、3-甲基丁醇、2,3-丁二醇、苯乙醇、正丙醇、己醇、乙酸己酯、辛酸乙酯、壬酸乙酯、2-苯基乙酸乙酯、十二酸乙酯、乙酸乙酯、2-甲基乙酸丙酯、3-甲基乙酸丁酯、己酸乙酯、乙酸。     

猕猴桃果酒香气成分的固相微萃取GC/MS分析

采用固相微萃取法提取、富集秦美猕猴桃果酒中的香气成分,经GC-MS分离与分析,共鉴定出64种化合物,其含量占挥发性成分的96.44%,包括酯类、醇类、酸类、醛酮类、烃类以及少量的其他化合物,以酯类、醇类、酸类化合物为主.其中主要成分为乙酸-3-甲基丁酯、3-甲基丁醇、苯乙醇、辛酸乙酯、癸酸乙酯、乙酸乙酯、乙酸苯乙醇酯、已酸乙酯、辛酸、2-甲基丙醇、乙酸-2-甲基丙酯、癸酸、乙酸己酯、己酸等.这些物质的共同作用形成了猕猴桃果酒独特的风味.     

Characterisation of volatile compounds in an alcoholic beverage produced by whey fermentation

An alcoholic beverage (35.4% v/v ethanol) was produced by distillation of the fermented broth obtained by continuous whey fermentation with a lactose-fermenting yeast Kluyveromyces marxianus. Forty volatile compounds were identified in this drink by gas chromatography. Higher alcohols were the most abundant group of volatile compounds present, with isoamyl, isobutyl, 1-propanol, and isopentyl alcohols being found in highest quantities (887, 542, 266, and 176 mg/l, respectively). Ethyl acetate had the highest concentration (138 mg/l) among the esters. Besides higher alcohols and esters, other components, including aldehydes, acids and terpenes were also identified in the whey spirit. Considering that the quality of an alcoholic beverage can be evaluated by the relation between isoamyl alcohol/2-methyl-1-propanol and 2-methyl-1-propanol/1-propanol, which have to be higher than unity, it was concluded that a novel spirit of acceptable organoleptic characteristics can be produced by cheese whey continuous fermentation with K. marxianus.     

无水有机醇介质中盐酸对小麦淀粉性质的影响

研究了小麦淀粉在有机醇溶液中酸变性前后的物化性质。采用无水甲辞、无水乙醇、异丙醇及正丁醇为溶剂,用盐酸对小麦淀粉进行改性。结果表明:经酸处理的小麦淀粉与原淀粉相比,随有机醇介质(从甲醇到正丁醇)碳原子数量的增加,颗粒表面出现的形变逐渐明显、冻溶稳定性依次减弱、透光率依次增强,在不同温度下溶解度逐渐增加,膨胀度逐渐降低,但改性后淀粉的黏度很小,几乎检测不出。说明酸在不同有机醇介质中对淀粉的作用程度不同,从甲醇到丁醇依次增强。     

Heavy sulphur compounds, higher alcohols and esters production profile of Hanseniaspora uvarum and Hanseniaspora guilliermondii grown as pure and mixed cultures in grape must

Hanseniaspora guilliermondii and Hanseniaspora uvarum were tested in grape must fermentations as pure and mixed starter cultures with Saccharomyces cerevisiae. In pure cultures, the specific growth rates found were 0.29 h(-1) for H. uvarum, 0.23 h(-1) for H. guilliermondii and 0.18 h(-1) for S. cerevisiae. No significant differences were observed between these values and those obtained in mixed cultures. Results presented in this work show that growth of apiculate yeasts during the first days of fermentation enhances the production of desirable compounds, such as esters, and may not have a negative influence on the production of higher alcohols and undesirable heavy sulphur compounds. Growth of apiculate yeasts reduced the total content of higher alcohols in wines, when compared to those produced by a pure culture of S. cerevisiae. Furthermore, the highest levels of 2-phenylethyl acetate were obtained when H. guilliermondii was inoculated in grape musts, whereas H. uvarum increased the isoamyl acetate content of wines. Apiculate yeasts produced high amounts of ethyl acetate; however, the level of this compound decreased in mixed cultures of apiculate yeasts and S. cerevisiae. When S. cerevisiae was used as a starter culture, wines showed higher concentrations of glycerol, 2-phenylethanol and ethyl hexanoate. In mixed cultures of apiculate yeasts and S. cerevisiae, wines presented amounts of methionol, acetic acid-3-(methylthio)propyl ester, 4-(methylthio)-1-butanol, 2-mercaptoethanol and cis-2-methyltetrahydro-thiophen-3-ol similar to those produced by a pure culture of S. cerevisiae. An increase in the amounts of 3-(ethylthio)-1-propanol, trans-2-methyltetrahydro-thiophen-3-ol and 3-mercapto-1-propanol was obtained in wines produced from mixed cultures with H. guilliermondii.     

Purification and characterization of an enzyme that has dihydroxyacetone-reducing activity from methanol-grown Hansenula ofunaensis

An intracellular enzyme having reduction activity towards dihydroxyacetone (DHA), and that was induced by DHA, was purified and characterized from a methanol-grown yeast, Hansenula ofunaensis. After harvesting cells grown in a 1% methanol medium until the early stationary phase, the enzyme was purified through ammonium sulfate fractination and a series of ion-exchange, hydrophobic, and gel-filtration column chromatographies. SDS-PAGE and HPLC showed the enzyme to be a homo dimer composed of two identical subunits, each with a molecular mass of 38 kDa. The optimum pHs for DHA reduction and glycerol oxidation were 6.0 and 7.0, respectively. The optimum temperature for enzyme activity was 55 degrees C. The enzyme reduced several other compounds, including acetaldehyde, acetol, 2-butanone and 3-methyl-2-butanone, more effectively than it did DHA, while its oxidation activity was higher towards ethanol, 2-propanol, 1,2-propanediol, 2,3-butanediol and 1,3-butanediol than towards glycerol. The K(m) values for DHA in reduction and glycerol in oxidation were 430 mM and 4 M, respectively. The K(m) values for DHA in reduction and glycerol in oxidation were 430 mM and 4 M, respectively. The purified enzyme had high K(m) values for glycerol and DHA and low K(m) values for 2-butanol and butanone, although physiologically it had a role in DHA metabolism. There were similarities between the purified enzyme and sec-alcohol dehydrogenases reported previously in their behavior towards inhibitors and metal ions, as well as in their K(m) values for 2-butanol and 2-butanone, but differences in their subunit molecular masses and activities for ethanol. At pH 9.8, the oxidative activity of the purified enzyme for l-2-butanol was about eleven times higher than that for d-2-butanol.     

Thermal Unfolding of Gelatin in Solids as Affected by the Glass Transition

ABSTRACT: The thermal unfolding or denaturation of solid-state proteins during processing can affect their functionality. This project explored the relation between the glass transition temperature (T_g) and thermal unfolding temperature (T_m) using gelatin as a model system. Freeze-dried gelatin was prepared containing various polyol types at several concentrations. Using differential scanning calorimetry, T_m andT_g were determined. Moisture and polyols (that is, glycerol, xylitol, sorbitol, sucrose, and trehalose) promoted a lowering of both T_g andT_m, the extent of which depended upon the plasticizer type and concentration. For all the data, T_m > T_g, and a plot of T_m against T_g indicated a linear relationship ( R²= 0.95). These results suggest that formulations must be in the rubbery state to have the necessary mobility for hydrogen bond disruption that leads to protein unfolding. Glass transition data should be considered when developing processing parameters for proteinaceous systems.     

Extraction of Lipids from Cereal Starches with Hot Aqueous Alcohols

Cereal starches were extracted at 100°C with various proportions of lower alcohols and water to establish optimum conditions. Lipid yields generally exceeding 90% were obtained with one two-hour extraction of maize starch at 100°C when using not less than 14 ml of 75–85% methanol, 10 ml of 75% ethanol, 12 ml of 74–78% n-propanol, 14 ml of 74–78% isopropanol, or 17 ml of 84% n-butanol per gram of starch. Similar results were obtained with wheat A-starch ( > 8 μm granule diameter), wheat B-starch ( < 8 μm granule diameter) and rice starch using n-propanol-water, and with rice starch using methanol-water. Yields decreased if the proportions of alcohol and water were not kept within well-defined limits, especially with butanol and ethanol. The preferred conditions for complete recovery of lipids were two 2-hour extractions and one 1-hour extraction at 100°C with not less than 16 ml of 75% n-propanol per gram of starch.     

三种不同珠干红葡萄酒品质的对比性研究

选取烟台地区的赤霞珠、梅鹿辄和蛇龙珠葡萄为原料,采用相同的工艺酿造干红葡萄酒,对酒的品质进行对比研究。结果表明,酒中3-甲基-1-丁醇、2-甲基-1-丁醇、1-己醇、β-苯乙醇、4-羟基-苯乙醇、甘油、丁二酸单乙酯、1,4丁内酯和丁二酸二乙酯的含量为赤霞珠＞梅鹿辄＞蛇龙珠。赤霞珠、梅鹿辄葡萄酒中2-甲基-1-丙醇的含量均高于蛇龙珠葡萄酒。蛇龙珠葡萄酒中丙醇、1-丁醇、丁二醇的含量较高。蛇龙珠葡萄酒中乳酸含量最高,而梅鹿辄葡萄酒中酒石酸含量最高。梅鹿辄、赤霞珠葡萄酒中杨梅素、槲皮素含量分别为蛇龙珠葡萄酒的5.0倍、6.4倍和19.6倍、44.5倍。蛇龙珠葡萄酒中除对香豆酸外,其余酚类物质的含量较少。梅鹿辄和赤霞珠葡萄酒的感官得分高于蛇龙珠葡萄酒。     

Regeneration of immobilized Candida antarctica lipase for transesterification

Immobilized lipase from Candida antarctica was employed to convert triglycerides to biodiesel using alcohol. Immobilized lipase is frequently deactivated by lower alcohols with deactivation being caused by the immiscibility between triglycerides and methanol or ethanol. When the lower alcohol is adsorbed to the immobilized enzyme, the entry of triglycerides is blocked, which causes the reaction to stop. An alcohol with three or more carbon atoms, preferably 2-butanol or tert-butanol, can regenerate the deactivated immobilized enzyme. The present work established that the activity of immobilized lipase could be significantly increased when such alcohols were used for an immersion pretreatment of the enzyme. The activity of the commercially available immobilized enzyme, Novozyme 435, increased about tenfold in comparison to the enzyme not subjected to any pretreatment. Following complete deactivation of the enzyme by methanol, washing with 2-butanol and tert-butanol successfully regenerated the enzyme and restored it to about 56% and 75% of its original activity level, respectively.     

温度对固相微萃取法分析南果梨果酒香气的影响

应用顶空固相微萃取法(HS-SPME)和气质联用(GC-MS)快速测定南果梨果酒中的香气成分。设立不同的温度条件,研究温度对固相微萃法分析南果梨果酒香气成分的影响。结果表明,在不同温度下,酯类和醇类化合物是鉴定出的主要香气成分;乙醇、乙酸乙酯、2- 甲基-1- 丙醇、异戊醇、2- 甲基-1- 丁醇、丁酸乙酯、乙酸异戊酯、3- 甲硫基丙酸乙酯、苯乙醇、癸酸乙酯是不同温度下共有的成分,温度在40℃鉴定出的香气成分种类最多。     

11 种保健酒中挥发性成分的分析

采用硅胶柱层析法结合气相色谱-质谱联用仪,对中国劲酒、竹叶青酒、张裕至宝三鞭酒、椰岛海王酒等11 种保健酒中的挥发性成分进行了分析,并通过标准品比对和NIST 11谱库检索进行了定性、定量研究。结果表明：11 种保健酒中共鉴定出37 种化合物,醇类6 种、烃类12 种、酯类9 种、醛类4 种、酸类2 种、酮类2 种、含氮化合物和酚类化合物各1 种,其中含量较大的成分有1-丙醇、2-甲基-1-丙醇、3-甲基-1-丁醇、乳酸乙酯、柠檬酸三乙酯、5-羟甲基糠醛和乙酸;通过内标法,对11 种保健酒中的乳酸丙酯进行了定量分析,线性回归方程为y =1.059 3x＋0.01（r=0.995）,含量范围在0.02～0.74 mg/L之间。检出限为0.005 mg/L ,定量限为0.01 mg/L。使用MATLAB 7.0软件,对中国劲酒、阳春牌滋补酒、沱牌枸杞酒以及椰岛海王酒、张裕至宝三鞭酒和竹叶青的挥发性成分进行了进行单因素方差分析和帕累托分析,结果表明：6 种酒样中烃类化合物的含量具有显著性差异;重要挥发性成分有3-甲基-1-丁醇、1-丙醇、2-甲基-1-丙醇、2-丁醇、5-羟甲基糠醛、丁香酚、乳酸乙酯、己酸乙酯、乙酸异戊酯、乙酸苯乙酯、癸酸乙酯、柠檬酸三乙酯、糠醛、肉桂醛、乙酸、苯乙烯、十四烷、十五烷、十六烷、1,4-二甲基苯、二苯胺。