Adapting to climate change is crucial for Australian viticulture, with a shift towards drought-tolerant grape varieties being a potential strategy. This study explored the sensory and volatile profiles of three emerging red grape varieties – Montepulciano, Nero d’Avola, and Touriga Nacional – grown in Australia, comparing them to traditional varieties (Cabernet-Sauvignon, Grenache, and Shiraz). Thirty-six trained tasters used Rate-All-That-Apply (RATA) to assess 35 wines, and GC-MS analysis determined the volatile composition of the wines. Seventeen out of 35 targeted volatiles were revealed odour-active across all varieties. However, linalool, associated with floral notes, was odour-active only in Touriga Nacional. Conversely, 1,8-cineole was found in emerging varieties and Cabernet-Sauvignon, but not in Shiraz and Grenache. Canonical Variance Analysis (CVA) identified key volatile compounds characterising each variety. Touriga Nacional wines were most distinct, denoted by linalool and α-terpineol. Shiraz and Montepulciano shared similar volatile profiles, both distinguished by β-damascenone and 2-phenylethyl acetate. Cabernet-Sauvignon and Grenache were characterised by 2-phenylethanol, while Nero d'Avola showed overlap with this group while additionally featuring 1,8-cineole. Sensory and volatile profiles suggest potential similarities between Shiraz – Montepulciano and Grenache – Nero d’Avola wines, whereas Touriga Nacional generated more diverse red wine styles encompassing wines similar to mainstream varieties. Collectively, these findings highlight the potential of emerging varieties to complement traditional Australian red wines as sustainable warm climate options, with some varieties showing closer stylistic similarities to mainstream styles than others.

The adsorbents used to remove taint compounds from wine can also remove constituents that impart desirable color, aroma, and flavor attributes, whereas molecularly imprinted polymers (MIPs) are tailor-made to selectively bind one or more target compounds. This study evaluated the potential for MIPs to ameliorate smoke taint in wine via removal of volatile phenols during or after fermentation. The addition of MIPs to smoke-tainted Pinot Noir wine (for 24 h with stirring) achieved 35-57% removal of guaiacol, 4-methylguaiacol, cresols, and phenol, but <10% of volatile phenol glycoconjugates were removed and some wine color loss occurred. Of the MIP treatments that were subsequently applied to Semillon and Merlot fermentations or wine, MIP addition post-inoculation of yeast yielded the best outcomes, both in terms of volatile phenol removal and wine sensory profiles. Despite some impact on other aroma volatiles and red wine color, the findings demonstrate that MIPs can ameliorate smoke-tainted wine.

This pioneering investigation involved the application of accentuated cut edges (ACE) technique to Sauvignon blanc winemaking. The concentration of varietal thiol precursors in juice was significantly higher for ACE treatment compared to conventional crushing, with two-way or three-way interactions of the experimental factors, which included yeast strain and malolactic fermentation, being determined from the wine data. ACE yielded higher concentrations of 4-methyl-4-sulfanylpentan-2-one (4-MSP) and enantiomers of 3-sulfanylhexanol (3-SH) and 3-sulfanylhexyl acetate (3-SHA) in wines that were more abundant in phenolic compounds. Compared to Sauvy yeast strain, VIN13 produced greater amounts of 3-SH and 3-SHA but less 4-MSP with wines exhibiting lower intensity 'floral' and 'fruity' notes. MLF increased 3-SH and 4-MSP concentrations and led to wines that exhibited more non-fruity sensory attributes. The study revealed the potential of ACE for increasing varietal thiol concentrations in Sauvignon blanc wine and altering overall sensory profiles, with interactions involving yeast strain and MLF.

cis-2-Methyl-4-propyl-1,3-oxathiane (cis-2-MPO), arising from 3-sulfanylhexan-1-ol (3-SH) and acetaldehyde, was recently identified in wine, but the enantiomeric distribution was unknown. Such information could reveal influences on wine aroma, given the impact of chirality on odorant molecules. Herein, a stable isotope dilution assay employing headspace solid-phase microextraction with chiral gas chromatography-mass spectrometry was developed, validated, and applied to a selection of wines. Studies with (3R)-3-SH revealed the elution order of the cis-2-MPO enantiomers and the concentrations of (2R,4S)-2-MPO and (2S,4R)-2-MPO in the studied wines ranged from undetected to 250 ng/L and 303 ng/L, respectively. Strong positive correlations were found between (3R)-3-SH and (2S,4R)-2-MPO (r = 0.654), and (3S)-3-SH and (2R,4S)-2-MPO (r = 0.860). Additionally, cis-2,4,4,6-tetramethyl-1,3-oxathiane, constituted from acetaldehyde and 4-methyl-4-sulfanylpentan-2-ol (4-MSPOH), was identified in wine for the first time. This new 1,3-oxathiane, which presents a novel fate for 4-MSPOH, was detected in wines as a single enantiomer at up to 28 ng/L.

Varietal thiols are important wine aroma compounds that are generally less abundant in red wines. Accentuated cut edges (ACE), known for accelerating phenolic extraction, was applied to Shiraz winemaking and compared with conventional crushing (NOACE) to examine the effects on varietal thiol precursor extraction and thiol formation. Water addition to grape must and skin contact time (SCT) during fermentation were also assessed. Although there was no difference for precursors in the must, ACE significantly decreased 3-S-glutathionylhexan-1-ol concentration during fermentation. 3-Sulfanylhexan-1-ol and ethyl esters were significantly influenced by crushing method and/or SCT, with NOACE or shorter SCT yielding higher concentrations. Acetates, higher alcohols, fatty acids, and isoprenoids differed according to the interaction of crushing method and SCT, with ACE and shorter SCT significantly enhancing all groups except acetates. Volatiles in Sauvignon blanc and Pinot noir wines produced at commercial scale with ACE were briefly evaluated, suggesting an impact of grape variety.

研究优选胶红酵母与酿酒酵母不同混合发酵方案对季风性气候区干红葡萄酒的香气质量、多酚及颜色的影响,优化增香酿造技术方案.实验以陕西合阳梅鹿辄葡萄为试材,设计2种菌株不同比例同时接种和顺序接种策略酿造干红葡萄酒.酿造完成后,对葡萄酒样品的香气成分进行顶空固相微萃取结合气相色谱-质谱联用法定性定量分析,香气特征通过感官量化品评法描述,采用光谱法量化分析酒样的13个颜色与多酚相关指标.结果表明,高比例同时接种显著增加了品种香气成分的含量,尤其是C6化合物和硫醇,而顺序接种更利于释放萜烯类和β-大马酮香气成分;发酵香气中高级醇、C6～C12脂肪酸及其酯类的含量随优选酵母接种比例的升高而增加,顺序接种在提高乙酸酯和苯乙基类化合物含量上有明显优势.较高比例(4∶1)同时接种和顺序接种处理明显增加了酒样中总花色苷、黄酮醇、酒石酸酯的含量,显著提高了辅色花色苷比例.感官分析表明,高比例同时接种处理显著增强供试酒样果香和花香的同时,也增强了生青和动物味,而顺序接种处理适度增强果香和花香的同时却能降低不良气味.综上,优选胶红酵母与酿酒酵母不同接种处理的混合发酵干红葡萄酒具有差异明显的色泽风味质量特征,顺序接种适度增香的同时没有生成不良气味的风险,并且有利于改善色泽质量.

cis-2-Methyl-4-propyl-1,3-oxathiane (cis-2-MPO) was recently identified in wine and proposed to arise from the reaction of 3-sulfanylhexan-1-ol (3-SH) and acetaldehyde. However, the evolution profile of cis-2-MPO during alcoholic fermentation (AF) and storage and its relationship with varietal thiols and acetaldehyde production were unknown. These aspects were investigated by fermenting Sauvignon blanc juice with J7 and/or VIN13 yeast strains and assessing the stability of cis-2-MPO during wine storage. Moderate to strong Pearson correlations verified similar evolution trends between acetaldehyde, 3-sulfanylhexyl acetate, and cis-2-MPO, with initial increases and a peak during the early to middle stages of AF before consecutive decreases until the end. Contrarily, 3-SH correlated moderately only at the end of AF. A consistent decrease observed for cis-2-MPO when spiked into Sauvignon blanc wine and assessed during 1-year storage revealed its general instability, but acetaldehyde addition (100 mg/L), pH 3.0, and storage at 4 °C all appeared to retain cis-2-MPO. These results have implications for wine aroma and the potential for cis-2-MPO to act as a sink (or source) for 3-SH in wine over time.

Accentuated Cut Edges (ACE) is a recently developed grape must extraction technique, which mechanically breaks grape skins into small fragments but maintains seed integrity. This study was the first to elucidate the effect of ACE on Shiraz wine's basic chemical composition, colour, phenolic compounds, polysaccharides and sensory profiles. A further aim was to investigate any potential influence provided by ACE on the pre-fermentation water addition to must. ACE did not visually affect Shiraz wine colour, but significantly enhanced the concentration of tannin and total phenolics. Wine polysaccharide concentration was mainly increased in response to the maceration time rather than the ACE technique. ACE appeared to increase the earthy/dusty flavour, possibly due to the different precursors released by the greater skin breakage. The pre-fermentation addition of the water diluted the wine aromas, flavours and astringency profiles. However, combining the ACE technique with water addition enhanced the wine textural quality by increasing the intensities of the crucial astringent wine quality sub-qualities, adhesive and graininess. Furthermore, insights into the chemical factors influencing the astringency sensations were provided in this study. This research indicates that wine producers may use ACE with pre-fermentation water dilution to reduce the wine alcohol level but maintain important textural components.

Mixed fermentation of Pichia fermentans and Saccharomyces cerevisiae was designed to circumvent the problem of weak aroma in Chinese spine grape wines. Spine grape, “Xiang Pearl”, was used for wine production by red wine-making processes. Physicochemical indices were measured using titratable and spectroscopic methodologies. Volatiles were quantified by SPME-GC-MS, and aroma attributes were analyzed by trained panelists. Results showed mixed fermentation benefited color properties by improving total anthocyanin, polymeric anthocyanin, and total tannin contents. The content of varietal compounds, except those of thiols, were reduced, whereas fermentative compounds contents, especially those of higher alcohols, esters, and phenylethyls, were increased by mixed fermentation. Sensory analysis showed mixed fermentation enhanced fruity and floral traits in wine; this was confirmed by mathematical regression showing elevated levels of fermentative volatiles dominated the contribution to pleasant aroma, whereas reduced content of varietal compounds, with the exception of thiols, correlated negatively with favorable characteristics.

为了探索混合发酵中酵母生长动力学及糖苷酶活变化,评价优选的胶红酵母在葡萄酒增香酿造中的应用潜力,优化接种方案.以胶红酵母与酿酒酵母顺序接种发酵‘爱格丽’干白葡萄酒为处理,在发酵过程中,血球计数法测总酵母数量;p-NPG法测β-葡萄糖苷酶、鼠李糖苷酶、半乳糖苷酶及木糖苷酶活性;稀释平板法测2种酵母的生长变化,每24 h取样,单一酿酒酵母发酵为对照.酵母生长动力学显示,顺序接种方案有助于减慢发酵速率,酿酒酵母接种时间越晚,胶红酵母的生长量随之升高且生存时间增长.4种糖苷酶主要在发酵早期表现较高的活性,混合接种发酵显著提升鼠李糖苷酶、半乳糖苷酶和木糖苷酶活性的累积量.可见顺序接种有助于降低发酵速率,增长胶红酵母生长时间,提升糖苷酶的活性,且顺序接种48 h方案最具增香酿造的潜力.

To improve the aroma profile of Ecolly dry white wine, the simultaneous and sequential inoculations of selected Rhodotorula mucilaginosa and Saccharomyces cerevisiae were performed in wine making of this work. The two yeasts were mixed in various ratios for making the mixed inoculum. The amount of volatiles and aroma characteristics were determined the following year. Mixed fermentation improved both the varietal and fermentative aroma compound composition, especially that of (Z)-3-hexene-1-ol, nerol oxide, certain acetates and ethyls group compounds. Citrus, sweet fruit, acid fruit, berry, and floral aroma traits were enhanced by mixed fermentation; however, an animal note was introduced upon using higher amounts of R. mucilaginosa. Aroma traits were regressed with volatiles as observed by the partial least-square regression method. Analysis of correlation coefficients revealed that the aroma traits were the multiple interactions of volatile compounds, with the fermentative volatiles having more impact on aroma than varietal compounds.

Objective:The aim of this study was to explore the growth and esterase activities in the mixed culture fermentation of non-Saccharomyces yeast and Saccharomyces cerevisiae.Methods:Esterase activities of non-Saccharomyces yeast from southern Sichuan liquor pits were measured in liquid fermentation medium.One yeast strain with the highest esterase activity was selected and identified through sequence analysis of the D1/D2 domain of 26S rDNA.Then,the alcoholic fermentation of mixed cultures of the isolate and S.cerevisiae were performed in model grape juice medium to explore the yeast growth kinetics and the evolution of esterase activities from substrates with different carbon chain lengths (C2-C8).Three experimental groups were set up by inoculating the non-Saccharomyces yeast strain 48 and 96 h before or at the same time as S.cerevisiae,and their pure cultures were used as controls.Results:The isolate was identified as Pichia fermentans.The fermentation rate of pure S.cerevisiae was the fastest.The yeast population in mixed culture fermentation was higher,especially with 96 h sequential inoculation.During fermentation,the highest esterase activities were accumulated with simultaneous inoculation (574 mU/mL).The C8 substrate accumulated the highest esterase activity (178-227 mU/mL),while the C2 accumulated esterase activity was the lowest (46-66 mU/mL).Comparison of the cell growth kinetics and the evolution of esterase activities during fermentations revealed that esterase activities were correlated with the growth of yeasts and arrived at the highest value in the stationary growth phase.Conclusion:The simultaneous inoculation of the isolate and S.cerevisiae in model juice with higher C4-C8 accumulated esterase activities has a good application potential for aroma enhancement.

利用课题组前期优选的具有高β-葡萄糖苷酶活性的葡萄汁有孢汉逊酵母(Hanseniaspora uvarum)研究其与酿酒酵母(Saccharomyces cerevisiae)菌株混合发酵的动力学,为其葡萄酒增香酿造的应用提供理论和技术支持.实验选用陕西杨凌的爱格丽葡萄为原料,设计优选菌株提前酿酒酵母48 h接种和同时接种两个发酵处理,接种量1.0×106 CFU/mL,同时用YPD液体培养基进行两个处理的模拟发酵实验,实验以纯酿酒酵母发酵为对照.发酵过程中监测不同酵母菌数量、酒精体积分数、还原糖等指标,建立动力学模型.结果表明,提前接种处理中优选菌株生存数量最多,生存时间最长,在其对数生长期酒精生成和还原糖消耗速率最慢,但整体酒精发酵正常,酒精生成量不受影响,说明发酵过程中不良副产物生成量有限.因此,优选菌株提前酿酒酵母接种的混合发酵具有葡萄酒增香酿造的应用可能.

葡萄酒样本选择673款不同价格水平的进口干红葡萄酒.葡萄酒的香气特征采用经过培训的品尝员的感官描述分析得到,而后香气特征采用“葡萄酒香气轮”上的香气标准术语归类.供试葡萄酒香气特征被标准化后被分为12个香气类别,每一香气特征和香气类别在不同价格区段的出现频率经统计计算得到.结果表明:不同价格区段的进口葡萄酒具有的香气特征有差异,除了＞1 400元/瓶的葡萄酒之外,其余价格区段的葡萄酒香气特征的出现频率与价格水平之间存在多元线性关系.偏最小二乘回归模型确认了进口干红葡萄酒价格与香气特征之间的数学联系,即来源于陈酿中的香气特征与价格呈正相关,并且确认＞1 400元/瓶的进口葡萄酒产品属于奢侈品的特例.