Binding of oak volatile compounds by wine lees during simulation of wine ageing

The retention of wine volatile compounds by wine lees could have an influence on the quality of the product. The aim of this work was to study the binding of wine volatile compounds from oak wood by the wine lees during simulation of wine ageing. The compounds with the most affinity for the lees were eugenol, 4-propylguaiacol, 4-methylguaiacol, furfural and 5-methylfurfural. Lees also bound other compounds important for aroma in aged wine such as oak lactones, although to a lesser degree. Guaiacol and γ-nonalactone were the only compounds studied that were not bound by the lees. Because the lees bind important compounds to wine aroma, ageing red wine in oak barrel in presence of lees could diminish the impact of the aromatic compounds from oak wood on wine aroma.     

Sorption and diffusion properties of volatile phenols into cork

The sorption and diffusion properties of seven common volatile phenols in hydro-alcoholic medium placed in contact with natural cork were investigated to determine the influence of cork closures on the concentration of these compounds in wine. Weighted cork samples were immersed in model wine solutions containing selected concentrations of each compound and were sampled over time. Sorption coefficients ranged between 125 and 306 mg of aroma compound per kg of cork, while diffusion coefficients varied from 0.8 to 4.1 × 10⁻¹¹ m²/s. Sorption isotherms of guaiacol and 4-propylguaiacol, respectively, the lowest and highest sorbed compounds of an homologous series of guaiacol, accurately fit Henry’s model. Hydrophobicity of aroma compounds seems to be a determining factor in both diffusion and sorption. This could indicate a preferential pathway for diffusion through suberin, the more hydrophobic constituent of cork.     

Factors influencing the production of volatile phenols by wine lactic acid bacteria

This work aimed to evaluate the effect of certain factors on the production of volatile phenols from the metabolism of p-coumaric acid by lactic acid bacteria (LAB) (Lactobacillus plantarum, L. collinoides and Pediococcus pentosaceus). The studied factors were: pH, L-malic acid concentration, glucose and fructose concentrations and aerobic/anaerobic conditions. It was found that, in the pH range of 3.5 to 4.5, the higher the pH the greater the production of volatile phenols. This behaviour is correlated with the effect of pH on bacterial growth. Increasing levels of L-malic acid in the medium diminished the production of 4-vinylphenol (4VP) and stimulated the production of 4-ethylphenol (4EP) by L. plantarum NCFB 1752 and L. collinoides ESB 99. The conversion of 4VP into 4EP by the activity of the vinylphenol reductase may be advantageous to the cells in the presence of L-malic acid, presumably due to the generation of NAD+, a cofactor required by the malolactic enzyme. Relatively high levels of glucose (20 g/L) led to an almost exclusive production of 4VP by L. plantarum NCFB 1752, while at low concentrations (≤ 5 g/L), 4EP is mainly or solely produced. Part of the glucose may be diverted to the production of mannitol as an alternative pathway to regenerate NAD+. This is corroborated by the experiments done with fructose, a compound that can be used as an electron acceptor by some bacteria becoming reduced to mannitol. In anaerobiosis, the reduction of 4VP into 4EP is clearly favoured, which is consistent with the need to increase the availability of NAD+ in these conditions. This study shows that the amount and the ratio 4VP/4EP produced by LAB are greatly affected by certain environmental and medium composition factors. The behaviour of the bacteria seems to be driven by the intracellular NAD+/NADH balance.     

红葡萄酒"酒脚"的综合开发利用

在红葡萄酒发酵后和陈酿期间的处理中,倒罐后所剩余的罐底沉淀物就是红葡萄酒的"酒脚".如果"酒脚"得不到妥善的处理,就会对周边的自然环境产生污染和破坏.     

利用米酒糟培养泰山赤芝工艺条件研究

以米酒糟为主要原料,选择合适的碳源,采用液体深层发酵法培养泰山赤芝,以菌丝体干重、胞外多糖、胞内多糖的产量为指标,通过单因素试验确定了泰山赤芝的培养条件.在此条件下泰山赤芝的菌丝体干重可达14.62 s/L,胞外多糖产量可达3.01g/L,胞内多糖占菌丝体干重的20.22%.     

蛋白酶水解糯米酒糟的工艺优化

分别采用酒用酸性蛋白酶、木瓜蛋白酶水解糯米酒糟,优化提高水解液中氨基态氮含量的工艺条件。不同蛋白酶的水解实验结果表明,酒用酸性蛋白酶的水解效果最理想。糯米酒糟水解的最优条件为:加酶量2 000 U/g酒糟、料液比1∶3、pH3.5、温度40℃、时间5 h。在此工艺条件下,水解液中氨基态氮含量达到0.75 g/L,比初始糯米酒糟液提高了368.75%。     

酶解黄酒糟对料酒发酵的影响

为提高产品质量和黄酒糟的利用价值,以黄酒糟酶解物作为辅料生产料酒,探讨预处理方法对黄酒糟中酵母蛋白溶出率的影响,蛋白酶种类对黄酒糟蛋白酶解的影响,及酶解物的添加形式和添加量对料酒发酵的影响。沸水浴处理5 min有利于黄酒糟中酵母蛋白溶出,酵母蛋白溶出率较对照增加48. 21%;选择碱性蛋白酶酶解黄酒糟;以黄酒糟酶解混合物作为辅料,添加量为2. 0 g/L,与米醪共发酵制备料酒,料酒原酒液中氨基酸态氮和游离氨基酸含量分别为0. 521 g/L和3. 553 g/L,较对照分别提高391. 51%和404. 69%,其中氨基酸风味比值(鲜味和甜味氨基酸含量之和与苦味和涩味氨基酸含量之和的比值)为0. 690,较对照提高62. 35%。     

Cell viability and proteins release during ultrasound-assisted yeast lysis of light lees in model wine

Light lees that spent more than one year in barrels were used for ultrasound-assisted yeast lysis (22 W/L, 18 °C) in a model wine. For comparison, a classical yeast autolysis at mild temperature (25 °C) was performed. The effect of ultrasound on lees was evaluated by analysing the release of proteins and polysaccharides to the model wine, and the viability of the yeasts contained in the lees. Under conditions tested, ultrasound-assisted yeast lysis increased the concentrations of proteins and polysaccharides in the model wine due to the release of these compounds from yeasts. Unlike the classical autolysis, ultrasound led to a high cell disruption, and after 20 h of ultrasonic treatment, viable cells were hardly found. Furthermore, the final cell concentration for the ultrasound-assisted yeast lysis was much lower than that for the classical autolysis. The inactivation rate constant of ultrasound-assisted yeast lysis was 2.54 × 10⁻⁵ s⁻¹. Finally, the morphological changes in cells were examined by scanning electron microscopy to verify the effect of ultrasound on yeast cells.     

葡萄酒在酒泥上陈酿研究进展

酒泥是葡萄酒生产过程中产生的沉淀物,近年来在葡萄酒陈酿中应用越来越广泛.本文综述了一些有关葡萄酒泥的最新研究结果:酒泥对葡萄酒中的有害物质赭曲霉素A、农药残留等具有去除作用.酒泥释放出来的甘露蛋白对葡萄酒的稳定性和葡萄酒的香气有一定的改善作用.葡萄酒在酒泥上陈酿可以使香气更加复杂,口感柔和,质量得到提高,但也产生一些不需要的副产物,如生物胺.尽管关于酒泥的研究取得了一定的进展,但酒泥的成分多变,关于其各种组分对葡萄酒质量的影响还需要深入研究.     

桑椹果酒酒糟中原花青素提取工艺研究

选用溶剂浸提法从桑椹果酒酒糟中提取花青素.通过单因素和响应面(BBD)试验优化提取工艺.结果表明,影响花青素提取量因素的优先次序为提取温度＞固液比＞提取时间,较优的提取工艺条件为提取温度80℃、提取时间150.3min、料液比1∶20.在该条件下,花色素提取量的理论预测值为1.92264mg/g,实际验证为1.894mg/g,提取得率达到理论预测值的98.5％.     

废弃黄酒糟的开发利用

黄酒糟是黄酒酿造中的主要副产物,黄酒的平均出糟率约为20％～30％,数量相当可观,黄酒糟中残留的蛋白质较多,氨基酸种类齐全,营养价值高,具有广泛开发价值.该文综述了黄酒糟在制备调味品、风味酒、复合氨基酸以及作为酿酒的再生资源等多个领域的应用,为将来黄酒糟的处理以及废弃资源的再生利用提供了参考.     

乳酸菌产生挥发性酚的初步研究

对7株分离于葡萄酒中的乳酸菌产生挥发性酚的能力进行了研究。利用气相色谱对p-香豆酸和阿魏酸的代谢产物4-乙烯基酚和4-乙基酚的含量进行了测定。结果显示,有2株菌能够利用p-香豆酸产生较多量的挥发性酚;乳酸菌利用阿魏酸产生挥发性酚的能力低于利用p-香豆酸产生挥发性酚的能力。     

Role of lees in wine production: A review

The sometimes contradictory role attributed by scientists to lees in wine production is discussed in this review. Studies dealing with the importance of lees in the natural removal of undesirable compounds from wine, the effect of lees–wine contact on the volatile fraction of wines, the key influence of lees on biogenic amine contents in wines, the interactions between lees and phenolic compounds, and the importance of mannoproteins and lipids released by lees have been critically reviewed. Finally, the present exploitation of lees is also outlined.     

简述在酒脚上陈酿葡萄酒的几种观点

在酒脚上陈酿葡萄酒从前是在橡木桶中进行,目前越来越多地成功应用于大罐中. 酒泥有时被看做是宝,这就是为什么白葡萄酒在酒泥上陈酿的原因.这些浓稠得有时令人呕吐的沉淀物,却是酵母的基本成分,它有利于改善和提高葡萄酒的质量.     

Development of volatile compounds of cava (Spanish sparkling wine) during long ageing time in contact with lees

In order to study the evolution of volatile compounds during long ageing times in contact with lees (more than 2 years), Headspace–solid phase microextraction (HS/SPME) method was applied to different cavas (Spanish Sparkling wine). Two different fiber coatings were used: PDMS which extracts the analytes by partitioning and DVB–CAR–PDMS which extracts either by partitioning or physically trapped the target compounds. Even though the volatile profile obtained by gas chromatography/mass spectrometry (GC/MS) was similar, the triple phase seems to be more suitable to follow the development of the volatile profile during its ageing time. Hexyl, 2-phenylethyl and isoamyl acetates significantly decrease over time, while 1,2-dihydro-1,1,6-trimethylnaphthalene (TDN), vitispirane and diethyl succinate significantly increase during ageing in contact with lees.     

Impact of two Williopsis yeast strains on the volatile composition of mango wine

The aim of the research was to study the volatile composition of mango wine fermented with two Williopsis yeast strains: Williopsis saturnus var. mrakii NCYC500 and W. staurnus var. suaveolens NCYC2586. Thirty terpenoids, twenty‐six esters, ten alcohols, nine acids, seven aldehydes and ketones, two ethers, two phenols and one sulphur compound were identified in the mango wine fermented with strain NCYC500, while twenty‐seven terpenoids, thirty esters, eleven alcohols, eight acids, eight aldehydes and ketones, three ethers, two phenols, one sulphur compound and one furan were detected in the mango wine fermented with the strain NCYC2586. The kinetic changes, final concentrations and odour activity values of major volatiles were compared between the two Williopsis yeast strains and also with other yeast reported in the literature. The results showed that Williopsis yeast strains NCYC500 and NCYC2586 were high producers of acetic acid and acetate esters, but low producers of medium‐ to long‐chain fatty acids and their corresponding ethyl esters. Unlike mango wine fermented with Saccharomyces cerevisiae, most terpenoids derived from mango juice were retained in the resultant mango wine fermented with the two Williopsis yeast strains, suggesting the mango wine could retain the aromatic hints of fresh mango.     

Interactions between yeast autolysates and volatile compounds in wine and model solution

The addition of a commercial yeast autolysate to a model solution of five typical wine aroma compounds (ethyl octanoate, linalool, 2-phenylethanol, β-ionone and octanoic acid) was investigated considering different variables, such as temperature, pH and the presence of highly concentrated natural volatile substances in wine (e.g. 3-methyl-1-butanol). The interactions of such compounds with both yeast walls and released colloids were studied using gas chromatography, with liquid–liquid extraction and solid-phase microextraction. The results were compared with those obtained by adding the commercial product to a white table wine, spiked with the five standard compounds. The data confirmed that yeast walls mainly bind less polar molecules: their loss in synthetic medium seemed to increase at higher pH values. Temperature and pH affected differently the interactions between yeast colloids and volatile compounds in wine and model solution: in complex solutions (as the addition of 3-methyl-1-butanol demonstrated) the interaction mechanisms could be influenced by competitive or other matrix-related effects, which can reduce the binding of single compounds, or even enhance their volatility.