Effect of the modifier (Graciano vs. Cabernet sauvignon) on blends of Tempranillo wine during ageing in the bottle. II. Colour and overall appreciation

The effect of Graciano (GRA) (Spanish valuable variety of limited production) vs. Cabernet Sauvignon (CS) (world-wide known French variety) on the colour of wines from Tempranillo (TEM-base wine) (largely cultivated Spanish variety), was studied in wine blends prepared with 25% and 10% (v/v) of each modifier after 4, 6, 9, 16.5 and 23 months of ageing in the bottle. Although possessing pH values very similar to the base wine, the blends of TEM with GRA or CS wines showed chromatic changes (higher a*, C*, CI, %red and %dA, and lower h, %yellow, tint and L*) that were perceptible by the human eye, even when using as little as 10% of modifier wine. However, no differences in colour parameters were found between the TEM-GRA (90:10) and the TEM-CS (90:10) blends, and between the TEM-GRA (75:25) and the TEM-CS (75:25) ones, this being consistent with the results relating to the temporal evolution of anthocyanins and flavanols (Part I). Moreover, the results of the principal component analysis indicated that the degree of interrelation existing between the colour parameters and the phenolic components during ageing in the bottle was similar for the TEM-GRA and TEM-CS blends. From a practical point of view, the ANOVA analysis also demonstrated that for any of the modifier wines used, certain colour parameters and phenolic components allowed differentiation between the base wine and the 75:25 blends, whereas others allowed differentiation between the base wine and both the 90:10 and 75:25 blends, during the ageing period studied. Some similarities between GRA and CS as modifier wines of TEM blends were also found in terms of their organoleptic characteristics, also demonstrating that both varieties could render blended wines with better overall quality attributes than the base wine after 23 months of ageing in the bottle.     

Effects of mechanical thinning on fruit and wine composition and sensory attributes of Grenache and Tempranillo varieties (Vitis vinifera L.)

Background and Aims: Cost-effective yield control is required by the wine industry in order to reduce the existing worldwide wine surplus and to improve grape quality. The object of this study was to evaluate the chemical and sensory effects on the resulting wines of mechanical cluster thinning performed at different intensities on Grenache, and at different timings (pea size and veraison) on Tempranillo. Methods and Results: The experiments were conducted with a machine harvester in 2007 on two commercial vertical shoot-positioned vineyards in Spain's Rioja region. In both varieties, mechanical thinning was effective in yield reduction and resulted in more ripened fruit, and wines with higher alcohol and pH values, more intense colour and increased phenolic content. Regardless of the thinning intensity, sensory changes were less noticeable in Grenache than in Tempranillo wines. Of the latter, those from vines thinned during veraison were less aromatic and sour, but had increased astringency. Conclusions: Yield management through mechanical thinning induced changes to the chemical composition of fruit and wines as well as to the wines' aroma, taste and mouthfeel. The extent of the sensory implications seems to depend on several factors such as the variety and timing of thinning application. Significance of the Study: This is one of the first studies addressing the effects of mechanical thinning on the sensory properties of the resulting wine and has implications for viticultural management practices.     

The effect of pH on the formation of maillard-derived aroma volatiles using a cooked meat system

The effect of pH on the formation of volatile compounds was investigated using minced beef in which the pH was adjusted within the range 4.0–5.6, by the addition of hydrochloric acid before cooking. The strong buffering capacity of the meat ensured that the pH did not vary during heating. Volatiles were analysed using headspace concentration and gas chromatography-mass spectrometry. The total quantity of volatile compounds increased as the pH decreased. A number of furanthiols and their oxidation products were preferentially formed at acid pH; some of these compounds had strong meaty aromas. The formation of other heterocyclic compounds such as thiazoles and pyrazines were favoured by higher pH.     

Suitability of pre‐dawn and stem water potential as indicators of vineyard water status in cv. Tempranillo

Background and Aims: Irrigation management requires the collection of up‐to‐date information that allow growers to make rapid decisions, water potential being one of the most used parameters in irrigation scheduling. The goal of this research was to determine whether predawn (Ψpd) and stem (Ψs) water potential can be used equally well, quantifying the effect external factors have on the relationship between them. Methods and Results: Ψpd, mid‐morning (Ψs‐m) and noon (Ψs‐n) stem water potential were measured at seven cv. Tempranillo vineyards. Climatic conditions, vine growth and fruit load affected daily water potential dynamics. A greater decline of Ψs occurred when temperatures were higher and there was no dew formation, as well as under larger canopies and fruit load. While the relative impact of these variables on water potential was not particularly high, it was by no means negligible. Conclusions: Data collected in this study did not favour Ψpd, Ψs‐m or Ψs‐n as a preferred measure to evaluate plant water status. It is important to remark that similar Ψpd values do not necessarily indicate the same level of deficit, and that similar Ψs values do not always mean similar water availability. Therefore, a straightforward interpretation of Ψpd and Ψs can sometimes be misleading. Significance of the Study: The results obtained provide significant explanation to the lack of agreement in the literature regarding the most suitable time to measure water potential. Vineyard managers and scientists should select it according to the level of stress expected, climatic conditions and irrigation frequency.     

Dependence of wine sensory attributes on vine water status

The dependence of wine sensory attributes on the water status of the source vines was determined following vineyard irrigation treatments which included early and late season water deficits and continually irrigated vines. In both seasons, the experimental wines made from the different irrigation treatments did not differ in the concentration of residual sugar or ethanol, titratable acidity, or pH. The concentrations of anthocyanins and total soluble phenolics in the wines were greater from water deficit treatments than from continually irrigated vines. For sensory evaluation, a novel protocol for paired comparisons was developed to test separately for differences in wine appearance, flavour, taste and aroma; differences were detected for each wine comparison. In both seasons, continually irrigated wine differed from early and late season water deficit wine, and early season water deficit wine differed from late season water deficit wine in appearance, flavour, taste and aroma. The sensory differences were not attributable to differences in vine yield or fruit maturity. When professional wine tasters were sampled using similar tests, a majority was able to detect visual but not flavour differences between a selected pair of wines. It is concluded that, where vine water status can be altered, irrigation offers a means to manipulate wine sensory characteristics in the vineyard.     

Clarifying effect of different fining agents on mulberry wine

Fining experiments have been conducted on mulberry wine, in which five fining agents (bentonite, gelatin, casein, egg albumin and PVPP) were investigated. The effect of these agents on polyphenol content, colour intensity, antioxidant activity and aromatic profile has been determined. In general, all treatments improved the limpidity of the mulberry wines to some extent. The wine was mostly negatively affected by gelatin and led to the greatest reduction of phenol content (16.61%), colour intensity (32.26%) and antioxidant activity. Concerning aroma, the addition of PVPP, casein and bentonite both significantly altered the aroma profile. It is noteworthy that egg albumin led to the lowest diminution total phenol value (5.74%) and improvement of antioxidant capacity and colour among the tested fining agents. Furthermore, the aroma profile remained mostly unaffected by egg albumin. As consequence, the optimal fining agent for mulberry wine was egg albumin.     

Malolactic fermentation of Tempranillo wine: contribution of the lactic acid bacteria inoculation to sensory quality and chemical composition

Malolactic fermentation (MLF) of Tempranillo Rioja wines (Spain) inoculated with two lactic acid bacteria (LAB) strains were studied and compared with spontaneous MLF. Inoculation with selected Oenococcus oeni lyophila shortened MLF duration up to 19 days and lead to wines with more fresh and fruity characters, especially when implantation was 100%. We demonstrated modifications in the concentration of volatile and nitrogenous compounds and a good correlation between analytical and sensory attributes was also noted. In addition, the low initial amino acid concentration and the consumption of these compounds by the inoculated yeast strain during alcoholic fermentation resulted in wines with very low biogenic amines levels (under 3.75 mg L^?1) after MLF and 3 month storage period in all cases. The results showed the significance of choose the most suitable starter to elaborate quality wines and suggest the control of amino acid content in must and wine to prevent the formation of biogenic amines.     

我国果酒发展及研究现状

果酒是以水果为原料,经发酵、调配等工艺制得的低酒精度饮料酒,其保留水果原有的风味及营养成分,因符合当前人们的消费需求而深受喜爱。该文简述了果酒的营养价值、种类和工艺流程,从果酒菌株选育、复合果酒开发、多菌株混合发酵、降酸技术、澄清技术以及香气成分等方面介绍了我国果酒的研究现状,阐述了我国果酒行业发展现状及存在的问题,并对果酒行业的未来进行了展望,为果酒产业品质的深入研究提供参考。     

酒类香气物质研究进展

分析了酒类香气物质的研究状况,介绍了目前国内外酒类香气成分的分析方法,包括样品的前处理、定性分析、定量的方法以及研究进展,以期为酒类香气物质研究者提供参考。前处理的方法主要有直接进样、液液萃取、蒸气蒸馏、静态顶空、动态顶空、固相萃取、固相微萃取和搅拌棒萃取法等;定性分析采用气相色谱(GC)、质谱(MS)及多种仪器联用;定量分析法包括了归一法、内标法和外标法等。     

Anthocyanin fingerprint of clones of Tempranillo grapes and wines made with them

Background and Aims:  Different clones with distinctive enological characteristics have been identified in many grape cultivars, but data on differences in anthocyanin composition of clones of the same cultivar are scarce. Thus, it has been considered of interest to check changes in the anthocyanin fingerprint of six different clones of Tempranillo grapes grown in the same vineyard, and of wines made with them, over three consecutive years.
Methods and Results:  Data were submitted to different statistical procedures. Despite slight differences in the anthocyanin fingerprint of some clones (relative content of different anthocyanins analysed), variations from year to year were more important than differences in the anthocyanin profile of the clones considered. This fact was also observed when the content (mg/kg grapes) of those molecules was considered. Moreover, Tempranillo wines made with different clones could be classified by discriminant analysis, using the anthocyanin fingerprint or the levels (mg/L wine) of several anthocyanins as predictor variables, and the year grapes were collected as a classification factor.
Conclusions:  The anthocyanin fingerprint of six clones of Tempranillo grapes grown in the same vineyard and that of wines made with them over three consecutive years was affected mostly by weather conditions, despite slight differences in the anthocyanin fingerprint of some clones.
Significance of the Study:  This is the first report on the anthocyanin composition of different clones of Tempranillo grapes and of wines made with them, and indicates that anthocyanin fingerprint of Tempranillo wines depends mainly on agroclimatic factors, and not on genetic differences among clones.     

果酒成分研究进展

果酒成分包括非挥发性基质成分和挥发性芳香成分。前者决定了果酒的营养价值,后者赋予果酒独特的特征风味。果酒的非挥发性基质成分和芳香成分均对果酒品质起着至关重要的作用。文章分别阐述了果酒非挥发性基质和香气的组成,并探讨了果酒非挥发性基质成分对芳香成分挥发性的影响,为改善果酒品质和建立果酒品质评价体系提供一定理论依据。     

The effect of increased yeast alcohol acetyltransferase and esterase activity on the flavour profiles of wine and distillates

The fruity odours of wine are largely derived from the synthesis of esters and higher alcohols during yeast fermentation. The ATF1- and ATF2-encoded alcohol acetyltransferases of S. cerevisiae are responsible for the synthesis of ethyl acetate and isoamyl acetate esters, while the EHT1-encoded ethanol hexanoyl transferase is responsible for synthesizing ethyl caproate. However, esters such as these might be degraded by the IAH1-encoded esterase. The objectives of this study were: (a) to overexpress the genes encoding ester-synthesizing and ester-degrading enzymes in wine yeast; (b) to prepare Colombard table wines and base wines for distillation using these modified strains; and (c) to analyse and compare the ester concentrations and aroma profiles of these wines and distillates. The overexpression of ATF1 significantly increased the concentrations of ethyl acetate, isoamyl acetate, 2-phenylethyl acetate and ethyl caproate, while the overexpression of ATF2 affected the concentrations of ethyl acetate and isoamyl acetate to a lesser degree. The overexpression of IAH1 resulted in a significant decrease in ethyl acetate, isoamyl acetate, hexyl acetate and 2-phenylethyl acetate. The overexpression of EHT1 resulted in a marked increase in ethyl caproate, ethyl caprylate and ethyl caprate. The flavour profile of the wines and distillates prepared using the modified strains were also significantly altered as indicated by formal sensory analysis. This study offers prospects for the development of wine yeast starter strains with optimized ester-producing capability that could assist winemakers in their effort to consistently produce wine and distillates such as brandy to definable flavour specifications and styles.     

香格里拉产区特色非酿酒酵母及自然发酵葡萄酒香气成分的研究

以香格里拉产区澜沧江流域4个不同海拔葡萄园（布村、溜筒江、斯农和阿东）的酿酒葡萄赤霞珠为试材,对各地葡萄酒特色非酿酒酵母进行分离鉴定,并采用气质联用（GC-MS）法对各地自然发酵葡萄酒的香气成分进行分析。结果表明：各地赤霞珠自然发酵葡萄酒中共分离鉴定到非酿酒酵母9个属10个种,其中,葡萄汁有孢汉逊酵母（Hanseniaspora uvarum）在各地均有分离到;黏红酵母（Rhodotorula glutinis）在布村、溜筒江和阿东均有分离到;出芽短梗霉（Aureobasidium pullulans）、汉逊德巴利酵母（Debaryomyces hansenii）和美极梅奇酵母（Metschnikowia pulcherrima）为斯农独有;而核果梅奇酵母（Metschnikowia fructicola）、季也蒙毕赤酵母（Meyerozyma guilliermondii）和克鲁维毕赤酵母（Pichia kluyveri）为阿东独有;浅黄隐球酵母（Cryptococcus flavescens）为溜筒江独有。这些非酿酒酵母使得各地自然发酵葡萄酒的香气各具特色,其中以醇类、酯类和芳香族类香气种类与含量的差异最为突出。     

新疆产区小芒森葡萄酒香气品质特性研究

小芒森是酿造天然甜酒的理想品种,该研究选用新疆五家渠、玛纳斯地区以及山东烟台地区的小芒森葡萄果实酿造的葡萄酒为材料,利用气相色谱-质谱法（GC-MS）对小芒森葡萄酒中的香气物质组成进行定性、定量分析。结果表明,小芒森葡萄酒香气物质的种类和含量受地区的影响,地区间差异主要体现在醇类和酯类的种类和含量上,新疆产区小芒森葡萄酒醇类和酯类总体都高于山东烟台地区,可达1 500 mg/L以上,赋予了葡萄酒丰富的水果香气。其次新疆产区的共性香气物质为乙酸乙酯、乙酸异丁酯、癸酸乙酯、己酸异戊酯、癸酸。根据这些结果,反映出小芒森葡萄酒在新疆产区所具有的香气特性,这将为提高新疆产区小芒森葡萄酒香气品质提供一定的理论基础。