Intensity of taste and astringency sensations elicited by red wines is associated with sensitivity to PROP (6-n-propylthiouracil)

The relationship between sensitivity to 6-n-propylthiouracil (PROP) and taste and astringency perception elicited by red wines was examined. Twenty-five subjects were classified into three PROP sensitivity groups (non-tasters, tasters and super-tasters) based on their bitterness ratings of a 0.32 mM PROP solution as measured on a Labeled Magnitude Scale (LMS). In a completely randomized block design, subjects used the LMS to rate the bitterness, astringency and acidity intensities of three commercial red wines. Contrary to the findings of previous studies with wine, bitterness, astringency and acidity intensities were all correlated with individual PROP taster status. PROP non-tasters gave significantly lower intensity ratings for the bitterness, astringency and acidity of the red wines than did PROP tasters and super-tasters. Individual differences among taster groups may be related to preference and consumption behavior of consumers of wine and other alcoholic beverages.     

Sensory changes during bottle storage of Spanish red wines under different initial oxygen doses

Sixteen commercial Spanish red wines selected to cover a wide range of sensory properties were stored at 25 °C for 6 months in air-tight containers under different oxygen doses (0–30 mg L^− 1) mimicking real and extreme bottling situations. The 16 initial samples (before storage) and the 80 stored samples (16 wines × 5 oxygen doses) were submitted to sensory analysis. Sensory changes related to post-bottling storage and initial oxygen dose were evaluated by means of discriminant and characterisation sensory strategies.Significant increases in black fruits, dried fruits, woody, lactic and stronger increases in cooked vegetables and spicy notes reveal a general pattern of aroma evolution. Remarkable departures to this general pattern have been observed, which can be related to the initial sensory properties of the wines and to their basic polyphenolic composition. The effect of post-bottling storage in bitterness is wine dependent, while global decreases in both global intensity and persistence evaluated in mouth are observed. Discrete increases in astringency are observed for wines with the lowest initial astringent scores. Important sensory interactions between aroma attributes (herbal and spicy) and bitterness and between roasted and astringency perception are shown. Little impact of the initial oxygen dose in the in-mouth sensory properties is reported. These results are relevant for wine experts in that they help understanding the evolution of wine sensory properties in the bottling stage. This study may help them to develop strategies for managing this winemaking stage with objective criteria.     

基于电子舌技术的襄阳市售米酒滋味品质评价

本研究采用电子舌技术和多变量统计学方法相结合的手段,对湖北襄阳市市售米酒的滋味品质评价分析。结果表明,41个市售米酒样品间基本味觉和回味指标差异均非常显著(p<0.01),通过主成分和围绕中心点的分割算法分析均发现市售米酒样品依据其滋味品质均可划分为两个聚类,由冗余分析发现两个聚类间的差异是由于涩味、苦味以及后味A(涩味的回味)等三个指标导致的。由此可见,电子舌作为一种新型的现代化智能感官仪器,在米酒的滋味品质评价中具有巨大应用潜力。      

Optimization and validation of a taste dilution analysis to characterize wine taste

ABSTRACT:  A procedure for the general taste dilution analysis (TDA) of wine has been optimized and applied to characterize the tastants of 5 different wines. Samples are concentrated first by vacuum distillation at 20 °C to obtain a dearomatized concentrate. Such concentrate is redissolved in water and injected in a semipreparative C18-high performance liquid chromatography (HPLC) column. The effluent is separated in fractions that are collected and concentrated by vacuum distillation. Sequential dilutions of the fractions are further evaluated by a sensory panel to assess the intensity of the basic tastes and in-mouth sensations. Fractions were also submitted to HPLC-mass spectrometry (MS) analysis to screen for known tastants of wines. The Taste Dilution chromatograms showed that taste differences between wines are mainly located in fractions 1, 2, and 6, and are mainly related to bitterness and astringency. Different aspects of the method setup and of its reliability are evaluated and discussed.     

Bitterness and astringency of grape and wine polyphenols

Extracts containing anthocyanins (ACN), and skin tannins (SKIN) and seed tannins (SEED) were prepared from Vitis vinifera cv. Cabernet Franc grapes grown in the Loire Valley, and characterised. Phenolic fractions from Cabernet Franc wines made from three Loire Valley locations were also isolated and characterised. Bitterness and astringency of ACN, SEED and SKIN as well as the wine extracts were evaluated by time intensity procedures in citric acid solution and in a base white wine. SEED and SKIN were equally astringent when tasted at the same concentration in spite of differences in tannin composition. The lower molecular weight (MW) of SEED was equal in astringency to larger MW SKIN which had a lower percentage of galloylation. The SEED fraction was slightly more bitter than the SKIN fraction in the citric acid solution, although no difference could be detected between samples in base white wine. Astringency of ACN alone was much lower than either SKIN or SEED. Addition of ACN to either tannin fraction produced very small sensory effects in citric acid. In wine, addition of ACN to either SEED or SKIN increased astringency significantly over either fraction alone, but had no effect on bitterness. The wine fractions differed only in astringency, which was correlated with tannin units as determined by thiolysis.     

Insights on the chemical basis of the astringency of Spanish red wines

The main goal of the present study is to provide an insight on the role played by non-volatile molecules on the different in-mouth attributes, particularly astringency. For achieving such goal, the main in-mouth sensory attributes of 34 oaked Spanish red wines were measured by a trained panel. The wine content in 30 sensory-active molecules was analysed by different HPLC based methodologies together with classical enological parameters and two proanthocyanidin indexes. Fourteen compounds (aconitic acids, polymeric proanthocyanidins, caftaric, caffeic and coutaric acids and seven quercetins) were found to be at concentrations above reported taste thresholds and to have a reasonably high range of occurrence. Two highly statistically significant models for astringency were built with those compounds. Even if the models could not be fully validated by sensory addition experiments, the research has demonstrated that wine astringency is driven by polymeric proanthocyanidins and by certain phenolic acids, the rate trans/cis-aconitic acid and flavonol profiles. The research has highlighted the existence of extremely complex interactions between non-volatile compounds on the in-mouth sensory perception. Particularly remarkable is the lack of additivity and potential antagonism found between the pairs cis/trans-aconitic acids, between aconitic and caffeic acids and between quercetin-3-O-galactoside and quercetin-3-O-glucoside. Also remarkable was the sweetness × astringent interaction and the matrix-dependence of the sensory responses elicited by flavonols. These results suggest the need for new paradigms and experimental procedures for fully decoding the real sensory relevance of individual non-volatile compounds in the overall wine flavour.     

Sensory assessment and chemical measurement of astringency of Greek wines: Correlations with analytical polyphenolic composition

The purpose of this study was to measure the astringency of selected Greek red wines and to assess the relationship between sensory and chemical data. Nine red wines produced by three native Greek grape varieties (agiorgitiko, xinomavro and mavrodafni) were used and their astringency and bitterness was assessed by a trained panel. In addition, their astringency was estimated chemically employing the ovalbumin precipitation method. Their polyphenolic composition was also determined by High Performance Liquid Chromatography (HPLC). The sensory data showed that mandilaria was the most astringent variety whereas agiorgitiko was the least. Statistical analysis of the results indicated that the chemical data obtained for astringency significantly correlated with the sensory determinations. In addition, significant correlations were obtained between the sensory data and the wine polyphenolic composition.     

Influence of sour rotten grapes on the chemical composition and quality of grape must and wine

This study evaluated the effect of grape sour rot on wine fermentation and characterized the chemical composition and the sensory changes in wines produced from rotten musts. Microvinifications were performed during two vintages using healthy Trincadeira and Cabernet Sauvignon red grape varieties to which were added grapes affected by sour rot. Increasing sour rot percentages, up to 50%, contributed to a clear decrease in free run must and final wine yields and induced significant changes in grape must chemical composition expressed by the increase in sugar content, total acidity, volatile acidity, anthocyanins, total phenols, and color intensity. After malolactic fermentation, wines from rotten grapes showed higher values of alcohol content, dry extract, reducing sugar content, total and volatile acidity, anthocyanins, total phenols, and color intensity. Despite the higher levels of reducing sugars, the microbial stability was similar to that of healthy wines. The sensorial evaluation, after malolactic fermentation, showed that both types of wine were not statistically different regarding color, aroma, taste, and overall quality. During 6–8 month storage, wines from rotten grapes showed a significant higher percentage of color loss, suggesting that sour rot is responsible for the decrease in color stability. Nevertheless, the results of sensorial analysis demonstrated that the fermentation of grape musts containing up to 30% sour rot yields wines with similar or even higher-quality scores than wines made with healthy grapes.     

Phenolic composition and sensory characteristics of Cabernet Sauvignon wines: effect of water stress and harvest date

The effect of three water status level and two harvest date 55 and 64 days after veraison (DAV) on phenolic and sensory composition of Cabernet Sauvignon wines were investigated. The later harvest date led to wine with a higher alcohol content. Total phenols varied from 1439.66 to 1643.08 mg L^?1 with higher values at 64 DAV. No differences were observed between irrigation treatments. For total tannins and anthocyanins, no differences were found between harvest date. Separation of proanthocyanidins by Sep‐Pak Plus tC₁₈ cartridges showed only differences in concentration but not in the proportion of proanthocyanidin fractions. The wines from the most restricted treatment had a better colour and the same aroma of red fruits, persistence, astringency, fullness and bitterness, as the wine from the treatment with highest irrigation. Under the assay conditions, it was possible to obtain wines with a similar chemical and sensory composition earlier and using less irrigation water.     

Grape seed removal: effect on phenolics,chromatic and organoleptic characteristics of red wine

Winemakers are interested in wines with low bitterness and astringency, and therefore, there is a preference for a higher presence of skin proanthocyanidins in wines. However, the information regarding the effect of reducing or eliminating seed proanthocyanidins from the must or fermenting wine on the characteristics of finished wines is scarce. For this reason, we elaborated a wine using Monastrell grapes from which the seeds had been removed and compared it with a control wine (CW) made from intact grapes. The anthocyanin and proanthocyanidin concentration and profile, and the chromatic and sensory characteristics were studied. The absence of seed proanthocyanidins did not affect anthocyanin concentration, although the proanthocyanidin concentration was 40% lower than in the CW. The copigmentation (CA) study showed that both wines had a similar extent of CA phenomena although colour intensity was higher when seed proanthocyanidins were present. The panellist evaluated the wines elaborated without seeds as being fruitier, less astringent and with an overall higher quality.     

GC-MS法分析柠檬蒸馏酒与发酵酒挥发性风味物质

采用定量描述性感官评价法对柠檬发酵酒与蒸馏酒进行感官评定,检测其理化指标,并利用气质联用（GC-MS）技术分析其挥发性风味物质组分及含量。结果表明,2种柠檬酒口感接近,除涩味外,苦、酸、甜味无显著差异（P＞0.05）;总酸、还原糖和可溶性固形物含量差异均显著（P＜0.05）;通过GC-MS技术从柠檬发酵酒与蒸馏酒中分别检测出40种、33种挥发性风味物质,且均以酯类物质种类（20种、15种）及相对含量（53.63%、48.43%）最高。与柠檬发酵酒相比,除检测到酯类、醇类、酸类、醛类物质外,柠檬蒸馏酒中还检测到烷烃类、杂环类及烯类物质。