Chemical affinities between the major volatile compounds present in a grape pomace distillate

BACKGROUND: The distillation of vinification by‐products to obtain alcoholic drinks is potentially an important source of income for the producing countries and avoids the environmental problem of waste management. Traditional technologies of distillation involve an important cost in terms of time and staff. Nowadays, companies install new distillation equipment, with high capacity and equipped with rectification columns, which is an important advance. Nevertheless, few studieshave been published concerning their correct management. In this study, the major volatile compounds were determined by gas chromatography in 61 samples of grape pomace distillate, corresponding to the fractions collected during seven complete distillation cycles. RESULTS: With a high degree of significance, the concentrations of 1,1‐diethoxyethane, propanol, hexanoate and ethyl acetate present positive correlations with the ethanol. However, those of benzyl alcohol, 2‐phenylethanol, furfurol, lactate, ethyl mirystate and diethyl succinate, were negative, which indicates that both groups of compounds were vented in the fractions of major or minor alcoholic degree, respectively. In addition, knowledge of the relationships between the volatile compounds contributes to improved management of an industrial distillation unit. CONCLUSION: The correlations established between the concentrations of the different volatile compounds indicate their physico‐chemical affinities or their biochemical origin. Copyright © 2009 Society of Chemical Industry     

Changes in volatile compounds during maturation of some grape varieties

The evolution of volatile compounds in three Vitis vinifera varieties (Monastrell, Cabernet Sauvignon and Tempranillo) was followed during maturation to determine whether they could be used as a maturation index. The volatile compounds were extracted and analysed by gas chromatography and gas chromatography-mass spectrometry. The volatile compounds of these non-aromatic varieties generally occurred in very low concentrations and only the C₆ compounds appeared in sufficiently high concentrations for their evolution to be followed and used to determine optimum maturity.     

Spent grape pomace as a still potential by‐product

This research consisted of the determination of several phenolic compound and fatty acid contents of the grape seeds and skins obtained from pomace PRE and POST distillation. The quantification of flavan‐3‐ol composition, the determination of the mean degree of polymerisation (mDP) of the condensed tannins and the estimation of their antiradical activity have been also realised. The distillation process applied did not seem to significantly affect the fatty acid distribution of extracted oils. Conversely, the antiradical activity of both seeds and skins changed. Heating significantly decreased the seeds’ activity, while increased the skins’ activity to around 50% compared to PRE sample. The conclusion from this study is that despite the degradation caused by the drastic conditions, many interesting, valuable compounds are still present in the extract from the waste of this process, which makes it a useful matter for a better exploitation than as fertiliser or for producing renewable energy.     

川西北干旱河谷地区赤霞珠葡萄果实花色苷的积累

花色苷是葡萄果实主要呈色物质,其积累受环境因素的影响.本研究以川西北干旱河谷地区的赤霞珠葡萄果实为试材,采用高效液相色谱-质谱联用以及荧光实时定量PCR技术分析了果实成熟过程中花色苷的组成与含量及部分关键酶基因的表达.结果表明,从果实完全转色至随后的3或4周内,是花色苷积累的高峰期;酰化和非酰化花色苷的相对比例及甲基化和非甲基化花色苷的相对比例不随成熟进程或年份而变化,但花翠素类与花青素类花色苷的相对比例受年份影响较大,降雨量是最主要的影响因子,它可能通过影响花色苷积累高峰期果实类黄酮代谢中F3'H和F3'5'H基因的表达而影响碳的分支流向.     

Characterization of free flavor compounds in traminette grape and their relationship to vineyard training system and location

ABSTRACT:  Free volatile flavor compounds in Traminette grape were characterized and compared to those in benchmark white cultivars by gas chromatography-mass spectrometry with headspace solid phase microextraction. In addition, the effects of vineyard site location (hot compared with cool based on growing degree days) and various training systems on yield components, standard characteristics (Brix, pH, and TA), and flavor compounds in Traminette grape juice were also evaluated for 2 seasons. Twenty-two free volatiles were identified in Traminette juice. The most abundant volatile compounds included hexanal, trans -2-hexenal, linalool, nerol, and geraniol. These compounds were quantified and compared with those in Chardonnay, Gewürztraminer, and Riesling juice. The hexanal concentration was the highest in Chardonnay, and trans -2-hexenal concentration was the lowest in Riesling. Traminette contained the highest amount of monoterpenes, especially geraniol. Concentrations of free volatile compounds in Traminette varied between the hot site and the cool site. In fact, the concentrations of 6-carbon aldehydes were higher in Traminette grown in the cool site than those grown in the hot site, whereas monoterpenes were higher in the hot site than in the cool site. Among the 5 training systems, vines on the vertical shoot-positioned produced the highest amount of monoterpenes, specifically geraniol. Our study suggests that Traminette is a flavorful cultivar that contains free volatile flavor compounds similar to the parent Gewürztraminer, but at much higher concentrations. The accumulation of odor chemicals in Traminette was affected by vineyard location and training system. Finally, geraniol was the most characteristic odor in Traminette, and its presence can be used as a quality indicator for this cultivar.     

SPME-GC-MS测定葡萄原汁中的挥发性物质

葡萄原汁中的挥发性成分直接影响葡萄制品的感官质量.采用SPME-GC-MS(固相微萃取-气相色谱-质谱)对山葡萄和欧亚种葡萄原汁中的挥发性风味成分进行分析,共鉴定出65种风味物质,可分为酯、烯、醛、醇、酮、烷、呋喃、苯环、杂环等9大类.与欧亚种葡萄相比,山葡萄原汁中风味物质的种类和含量较多.从葡萄汁的风味体系上分析,山葡萄原汁中醛、醇、烯的组成较高;欧亚种葡萄原汁中酯、醛的组成较高.     

Anthocyanin profiles of major red grape (Vitis vinifera L.) varieties cultivated in Greece and their relationship with in vitro antioxidant characteristics

A range of fourty‐six red grape (Vitis vinifera spp.) samples, originating from six widely cultivated varieties and covering major parts of the Hellenic vineyard, were assayed for their content in six principal anthocyanin pigments. Representative in vitro antioxidant parameters were also determined, including antiradical activity (A_AR), reducing power (P_R) and hydroxyl free radical scavenging activity (SA_HFR). Quantitative determination using high performance liquid chromatography showed that the prevalent pigment was malvidin 3‐O‐glucoside (average content 82.53 mg per 100 g fresh berry weight), followed by its coumarate derivative (29.26 mg per 100 g), paeonidin 3‐O‐glucoside (10.84 mg per 100 g), petunidin 3‐O‐glucoside (7.80 mg per 100 g) cyanidin 3‐O‐glucoside (5.67 mg per 100 g) and delphinidin 3‐O‐glucoside (1.28 mg per 100 g). The richest variety was Syrah, with total average anthocyanin content of 186.02 mg per 100 g, whereas the Hellenic native variety Xinomavro had the lowest average anthocyanin level (38.70 mg per 100 g). The establishment of correlations of individual and total anthocyanin contents with the values from the antioxidant test was accomplished with linear regression. The links of total anthocyanins were significant with all antioxidant parameters (P < 0.001), but more importantly with SA_HFR (R² = 0.740). Malvidin 3‐O‐glucoside content had the higher correlation with SA_HFR compared with all other anthocyanins (R² = 0.698, P < 0.001).     

Comparative evaluation of the quality of red globe grape juice fermented by Lactobacillus acidophilus and Lactobacillus plantarum

Basic analysis, electronic senses and HS-SPME/GC-MS were used to evaluate the effects of single and mixed cultures of Lactobacillus acidophilus-26 and Lactobacillus plantarum-56 on the quality of fermented red globe grape (RGG) juice. The results showed that mixed culture fermentation was superior to single strain fermentation in terms of viable bacteria counts, consumption of total sugar (TS), total soluble solids, pH, functionality, and antioxidant properties of RGG juice (RGGJ). Whereas the aroma profiles of developing juices were dominated by abundant esters, acids, alcohols, aldehydes, and ketones. Compared with the single inoculation, co-inoculation of the two species induced lactic acid fermentations, leading to accumulation of acetic acid, ethyl acetate, and 2-hexenol significantly. Moreover, higher concentrations of ethyl acetate, benzoic acid ethyl ester, octanoic acid, sorbic acid, 2-phenylethanol, and 2-hexenol represented the characteristic flavours of juices. To sum up, these findings suggested that L. acidophilus-26 and L. plantarum-56 could be used as fermented strains to ferment and improve the quality of RGGJ.     

Anthocyanin profile of Spanish Vitis vinifera L. red grape varieties in danger of extinction

This paper reports on a study of the anthocyanin fraction in berry skins of ten minority red and pink grapevine varieties from Castilla-La Mancha (Spain) and two traditional varieties from this growing region, Tempranillo and Garnacha Tinta, as references. These varieties were correctly identified beforehand by analysing six microsatellite regions recommended by the GENRES 081 project; five varieties were identified with genotypes identical to those described previously, and five new genotypes not described for any variety according to the literature consulted. Grape skin extracts of each variety were analysed by HPLC-UV-Vis, and four perfectly differentiated anthocyanin profiles were obtained. In six out of ten varieties (Churriago, Unknown 1, Unknown 2, Ariño, Brujidera and Moravia Agria) the major anthocyanin was malvidin-3-glucoside (39%). Tinto Velasco contained more than 29% delphinidin-3-glucoside, Gordera Roja and Teta de Vaca Tinta more than 40% peonidin-3-glucoside, and Rojal more than 29% cyanidin-3-glucoside. Results of this work point out the existence of unusual anthocyanic profiles in several of these indigenous varieties, and highlight the necessity of studying the effects of variety on other flavonoids and their impact on wine colour.     

黄山野菊花挥发性化学成分的提取及分析

报道了用蒸馏-萃取法(1)和同时蒸馏-萃取法(2)提取黄山野菊花中挥发性物质，测得用两种方法提取的黄山野菊花挥发油含量分别为2．83％和3．37％。用GC/MS法从黄山野菊花挥发油中分别确定出37种、28种化学成分，分别占黄山野菊花挥发油总检出量的63．16％和61．16％。用峰面积归一化法得出各类化学成分在挥发油中的相对百分含量。     

Biochemical comparison of two grape varieties differing in juice acidity

The winegrape cv. Cabernet Sauvignon and the tablegrape cv. Gora Chirine (both Vitis vinifera L.) differ in the acidity of their berry juice. The changes in pH, titratable acidity and the concentration of compounds of the berry juice were measured from 20–30 d before veraison to harvest on plants cultivated in the glasshouse. The difference in acidity between the juice of the two varieties appeared before veraison. At harvest, the berry juice of Gora Chirine had a pH of 5.2 and titratable acidity (TA) of 32 meq/L while that of Cabernet Sauvignon had a pH of 3.2 and TA of 150 meq/L. To evaluate cellular compartmentation in the berry pericarp, vacuolar pH was measured on intact berries at two growth stages, using ¹³C nuclear magnetic resonance (NMR). Vacuolar pH did not differ significantly between the two cvs. The lower TA of Gora Chirine juice could be attributed to lower concentrations of all three major acids, malic, tartaric and citric, and to a higher concentration of potassium. At veraison, the malic acid concentration in the berry juice of Cabernet Sauvignon was about seven times higher than that of Gora Chirine. The accumulation of hexoses, especially glucose, occurred earlier during the berry growth cycle in Gora Chirine than in Cabernet Sauvignon. The osmotic potential of the Gora Chirine juice, before veraison, was lower than could have been expected because of low acidity. This was due to the compensatory effect of early accumulation of glucose. Amino acid concentration was significantly higher in Gora Chirine than in Cabernet Sauvignon, especially just before veraison. The role of organic acids in berry acidity and osmotic potential, and various metabolic processes that may lead to the difference in organic acid concentration, are discussed.     

Substantial water uptake into detached grape berries occurs through the stem surface

Background and Aims: Water uptake through the stem surface contributes to total water uptake of submerged grape berries (Vitis vinifera L.). The objective was to identify the site of this uptake. Methods and Results: Uptake of water and a fluorescent dye was studied using a single berry + stem system. To identify the site of water uptake, the cut end of the stem and selected regions of the stem surface were coated with a silicone sealant. Water uptake was determined gravimetrically. After immersing in dye solution, the stem and the receptacle region of the stem/berry junction fluoresced, but the exocarp did not. Fluorescence of vascular bundles in stem and berry indicated that the dye taken up was transported into the berry. Selective coating of the various stem parts revealed that at steady state (96 to 144 h), the stem/berry junction (0.11 ± 0.04 mg/h), receptacle (0.09 ± 0.03 mg/h) and the remaining stem surface (0.08 ± 0.03 mg/h) contributed approximately equally to total water uptake in the whole stem region (0.24 ± 0.05 mg/h), which in turn accounted for 55% of uptake of a berry + stem (0.43 ± 0.05 mg/h). Conclusions: Stem/berry junction, and periderms of abscission zones and lenticels represent regions of preferential water uptake into detached grape berries. Significance of the Study: Extrapolating from the single berry system to an intact bunch on a grapevine demonstrates that water uptake through the stem tissues inside a compact bunch may contribute to berry cracking under vineyard conditions.     

Impact of agronomic practices on grape aroma composition: a review

Aroma compounds are secondary metabolites that play a key role in grape quality for enological purposes. Terpenes, C₁₃-norisoprenoids, phenols, and non-terpenic alcohols are the most important aroma compounds in grapes and they can be found as free volatiles or glycoconjugated (bound) molecules. The non-volatile glycosylated group is the largest, and it is present in all varieties of Vitis vinifera (L.), the most widely used species for wine production. These aroma precursors represent the reserve of aroma molecules that can be released during winemaking. Their relative and absolute concentrations at fruit ripening determine the organoleptic value of the final product. A large range of biotic and abiotic factors can influence their biosynthesis in several ways. Agronomic practices such as irrigation, training systems, leaf removal, and bunch thinning can have an effect at plant level. The spraying of stimulatory compounds on fruit at different developmental stages has also been shown to modify metabolic pathways at fruit level with some impact on the aroma composition of the grapevine fruit. Viticulturists could act to promote aroma precursors to improve the aromatic profile of grapes and the wine ultimately produced. However, agronomic practices do not always have uniform results. The metabolic and physiological changes resulting from agronomic practices are unknown because there has not been sufficient research to date. This review presents the state of the art regarding the influences of vineyard agronomic management on the biosynthesis of grape aroma compounds. Although literature regarding the topic is abundant there are still many unknown biological mechanisms involved and/or that have been insufficiently studied. The aim of this work is therefore to find the gaps in scientific literature so that future investigations can focus on them. © 2018 Society of Chemical Industry     

The effects of homogenisation method and freezing on the determination of quality parameters in red grape berries of Vitis vinifera

The effect of sample processing with three different blenders, sample freezing and storage time on the determination of berry quality parameters – total anthocyanins, total soluble solids (TSS), total phenolics (TP) and pH – in homogenates of red grape berries has been examined. Samples of Cabernet Sauvignon, Merlot and Shiraz from four regions of South Australia were homogenised using Ultra-Turrax, Waring or Retsch commercial blenders applied to fresh samples, and to samples held in frozen storage overnight or for 1, 3, 6 and 12 months. All samples were analysed immediately after homogenisation. The results showed that neither homogeniser type nor freezing had any significant effect on total anthocyanins or TSS. However, freezing had an effect on total anthocyanins concentrations in samples with higher colour. The homogeniser type had a significant effect on TP and pH for all varieties analysed together. Freezing had no significant effect on TP, but significant effect on pH, the value being greater in samples at the lower end of the pH range. Frozen storage time of up to 3 months had no significant effect on total anthocyanins, TSS or T P. Statistically significant differences were observed in the concentration of total anthocyanins in samples after 3 months of frozen storage.     

光果甘草叶、根中挥发性成分气相色谱-质谱法分析

经同时蒸馏萃取法（SDE）提取得到新疆光果甘草叶、根中挥发性成分,采用气相色谱-质谱（GC-MS）联用技术,结合计算机检索进行分析和鉴定,通过色谱峰面积归一化法对各组分进行定量分析。最终从光果甘草叶与根中分别分析鉴定28种和16种化合物,并对各组分进行归纳分析。通过对比甘草叶、根中的挥发性物质发现,叶中具有较多对风味贡献良好的挥发性化合物。实验结果为甘草资源的进一步开发利用提供了理论指导。