Influence of Maceration Temperature in Red Wine Vinification on Extraction of Phenolics from Berry Skins and Seeds of Grape (Vitis vinifera)

The extraction of phenolics from berry skins and seeds of the grape, Vitis vinifera cv. Cabernet Sauvignon, during red wine maceration and the influence of different temperature conditions (cold soak and/or heating at the end of maceration) were examined. Phenolics contained mainly in berry skins, viz., anthocyanin, flavonol, and epigallocatechin units within proanthocyanidins, were extracted during the early stage of maceration, whereas those in seeds, viz., gallic acid, flavan-3-ol monomers, and epicatechin-gallate units within proanthocyanidins, were gradually extracted. In addition to their localization, the molecular size and composition of the proanthocyanidins possibly influenced the kinetics of their extraction. Cold soak reduced the extraction of phenolics from the seeds. Heating at the end of maceration decreased the concentration of proanthocyanidins. Thus, modification of the temperature condition during maceration affected the progress of the concentration of phenolics, resulting in an alteration of their make-up in the finished wine.     

A combined phenolic extraction and fermentation reactor engineering model for multiphase red wine fermentation

Red wine production begins with a simultaneous fermentation and solid-phase extraction process. Red wine color and mouthfeel is the result of the extraction of phenolics from grape skins and seeds during fermentation, where extraction is a strong function of temperature and ethanol concentration. During fermentation, grape solids form a porous “cap” at the top of the fermentor, resulting in a heterogeneous fermentation system with significant temperature and concentration gradients. In this work, we present a spatial, time-variant reactor engineering model for phenolic extraction during red wine fermentation, incorporating fermentation kinetics, mass transfer, heat transfer, compressible fluid flow, and phenolic extraction kinetics. The temperature and ethanol concentration profiles predicted by this model allow for the calculation of phenolic extraction rates over the course of fermentation. Phenolic extraction predictions were validated against prior experimental data to good agreement and compared to a well-mixed model's predictions to show the utility of a spatial model over well-mixed models.     

Creation and validation of a reactor engineering model for multiphase red wine fermentations

Red wine fermentations are performed in the presence of grape skins and seeds to ensure the extraction of color and other phenolics. The presence of these solids results in two distinct phases in the fermentor, as the solids float to the top to form a “cap.” Modeling of red wine fermentation is, therefore, complex and must consider spatial heterogeneity to predict fermentation kinetics. We have developed a reactor-engineering model for red wine fermentations that includes the fundamentals of fermentation kinetics, heat transfer, diffusion, and compressible fluid flow. To develop the heat transfer component of the model, the heat transfer properties of grapes were experimentally determined as a function of fermentation progression. COMSOL was used to solve all components of the model simultaneously utilizing a finite element analysis approach. Predictions from this model were validated using prior experimental work. Model prediction and experimental data showed excellent agreement. The model was then used to predict spatial profiles of active yeast cell concentration and ethanol productivity, as well as liquid velocity profiles. Finally, the model was used to predict how these gradients would change with differences in initial bioavailable nitrogen concentration, a key parameter in predicting fermentation outcome in nitrogen-limited wine fermentations.     

Impact of diurnal temperature variation on grape berry development, proanthocyanidin accumulation, and the expression of flavonoid pathway genes

Little is known about the impact of temperature on proanthocyanidin (PA) accumulation in grape skins, despite its significance in berry composition and wine quality. Field-grown grapes (cv. Merlot) were cooled during the day or heated at night by +/-8 °C, from fruit set to véraison in three seasons, to determine the effect of temperature on PA accumulation. Total PA content per berry varied only in one year, when PA content was highest in heated berries (1.46 mg berry(-1)) and lowest in cooled berries (0.97 mg berry(-1)). In two years, cooling berries resulted in a significant increase in the proportion of (-)-epigallocatechin as an extension subunit. In the third year, rates of berry development, PA accumulation, and the expression levels of several genes involved in flavonoid biosynthesis were assessed. Heating and cooling berries altered the initial rates of PA accumulation, which was correlated strongly with the expression of core genes in the flavonoid pathway. Both heating and cooling altered the rate of berry growth and coloration, and the expression of several structural genes within the flavonoid pathway.     

葡萄籽中原花青素提取方法优化处理

溶剂提取法是提取葡萄籽原花青素的常用方法 ,然而 ,在不同提取条件下 ,提取效果并不一致。利用水、甲醇、乙醇、丙酮及它们的水溶液提取葡萄籽中的原花青素 ,而后用铁盐催化比色法测原花青素含量 ,考察了提取剂的浓度、粉碎度对提取的影响。在优化处理的基础上 ,获得了有效的提取条件 :葡萄籽粉碎度 10 0目 ,提取剂 70 %甲醇水溶液。     

Separation of polymeric tannins from white wine by a combination of 2-butanol extraction and column chromatography

A new procedure was developed for the separation of polymeric tannins from a high-tannin white table Koshu wine by extraction with organic solvent and adsorption chromatography. The wine was adjusted to pH 1.0, sodium chloride was added to give a final concentration of 12.5% NaCl, then phenolic compounds including phenolic acids and tannin phenolics were extracted with 2-butanol. About 95% of the total phenolics was extractable.Polymeric tannins were separated from the extract by chromatography on Bio-Gel P-2, which adsorbs polymeric tannins in the presence of 10% acetic acid-50% ethanol, and recovered quantitatively by subsequent elution with 50% acetone. The phenolic acids and flavonoid tannins of low molecular weight that were eluted first using 10% acetic acid-50% ethanol, and the tannin phenolics of high molecular weight subsequently eluted using 50% acetone, were both free of potassium and sodium ions.This method, including the extraction and chromatography, is useful for rough separation of polymeric tannins and other phenolics from white wines.     

Berry morphology and composition in irrigated and non-irrigated grapevine (Vitis vinifera L.)

The present study was carried out in a 5-year-old vineyard (Vitis vinifera L., cv. Aglianico) located in Southern Italy. Half of the plants (IRR) were fully irrigated, whereas the other half were not irrigated (NIRR). In both of the treatments, plant water status, gas exchange, photosynthetic efficiency and productive performance were determined. The arid conditions resulted in significant decreases in stem water potential in NIRR (minimum values of -1.34 and -1.52 MPa in IRR and NIRR, respectively). The values of yield per plant, cluster weight and total berry weight were significantly higher in IRR. Grape berries were separated into four weight classes, and morphometric and microscopic analyses were carried out to measure and calculate berry skin characteristics. Irrigation determined a marked shift toward heavier (+23% in the class ≥ 1.25 g) and bigger (336.35 mm3 vs 299.15 mm3) berries, and induced significant changes in other morphometric berry parameters. No differences among berry weight classes and irrigation treatments were observed for berry skin thickness. In all of the berry weight classes, total anthocyanins extracted from berry skins were significantly higher in NIRR than in IRR (12301.53 and 9585.52 mg kg?1 fresh berry skin, respectively), and appeared to be positively related to berry weight, whereas total flavonols were not significantly different between the two treatments. Qualitative changes in the levels of single anthocyanin and flavonol compounds were detected between IRR and NIRR. In addition, iron, copper and zinc, whose high concentration can negatively affect wine quality, were significantly higher in the IRR treatment. The results highlighted that the absence of irrigation did not determine decreases in grape quality. Such data can be of primary importance in environments where water availability is by far the most important limiting factor for plant growth.     

Lignin-derived oak phenolics: a theoretical examination of additional potential health benefits of red wine

Lignin-derived phenolic compounds can be extracted from oak barrels during the aging of red wine, and it is hypothesized that these compounds may contribute to the health benefits of red wine by their antioxidant, radical-scavenging, or chemopreventive activities. Density functional calculations (B3LYP/6-311++G**) support the radical-scavenging abilities of the oak phenolics. Sinapaldehyde, syringaldehyde, syringol, and syringylacetone all have bond dissociation energies that are lower than resveratrol and comparable to the flavonoid catechin. Molecular docking studies of the oak phenolics with known resveratrol protein targets also show that these compounds dock favorably to the protein targets. Thus, lignin-derived oak phenolics, although found in small concentrations, may contribute to the beneficial antioxidant, chemopreventive, and cardioprotective effects of red wine.     

Dynamic superheated liquid extraction of anthocyanins and other phenolics from red grape skins of winemaking residues

Grape skins from a grape pomace were subject to extraction with superheated ethanol-water mixtures for quantitative extraction of anthocyans and other phenolic compounds. The variables affecting dynamic extraction of these compounds were studied and identification and quantification of the extracted compounds were performed by both direct spectrophotometry or after HPLC separation using UV or MS detectors. The optimal working conditions for total extraction of anthocyans were: 1:1 (v/v) ethanol-water acidified with 0.8% (v/v) HCl, 120 degrees C, 30 min, 1.2 ml/min and 80 bar. The yields of anthocyanins, total phenolics and flavanols thus obtained were much higher (3 times for anthocyanins, 7 times for total phenolics and 11 times for flavanols) than those provided by dynamic conventional solid-liquid extraction. Several sample preparation procedures for skins as alternatives to free-drying were also investigated and drying at 40 degrees C for 24h provided the best results. Extraction with acidified water provides similar composition and poorer efficiency than 1:1 ethanol-water; also similar to two commercial grape skin extracts used as natural colorants.     

Localization of volatile acidity reducing factors in grape

Summary Must clarification processes cause an increase in the acetate content of wine at the end of the alcoholic fermatation process, this phenomenon being particularly noticeable when fermentation is obtained by means of the so-called high acetate-producer yeast strains. The influence of different must fractions (free run juice, pressed juice, skins and seeds) on acetate production in white grape was investigated, and the addition of skins and and seeds to a synthetic nutritive medium (MNS) was seen to cause a considerable reduction in acetate production. Strain-related differences become evident when the grape bunch is subjected to heat shock (90°C) before musting. In such conditions, acetate content after fermentation is approximately the same as that of the control specimen (not heat treated) for the low acetate-producer strain (S191c) and higher for the high producer strain (S22b). This suggests the presence of some thermolabile factor that is responsible for inhibiting acetate production. In order to determine the chemical nature of this factor, a series of tests was performed on two substances contained in grape skins and seeds, i.e., polyphenolic compounds and unsaturated fatty acids. A reduction in acetate production was observed in the presence of both substances, their effect being greater when used in connection with high acetate-producer yeast strains.     

Proanthocyanidins--a final frontier in flavonoid research?

Proanthocyanidins are oligomeric and polymeric end products of the flavonoid biosynthetic pathway. They are present in the fruits, bark, leaves and seeds of many plants, where they provide protection against predation. At the same time they give flavor and astringency to beverages such as wine, fruit juices and teas, and are increasingly recognized as having beneficial effects on human health. The presence of proanthocyanidins is also a major quality factor for forage crops. The past 2 years have seen important breakthroughs in our understanding of the biosynthesis of the building blocks of proanthocyanidins, the flavan-3-ols (+)-catechin and (-)-epicatechin. However, virtually nothing is known about the ways in which these units are assembled into the corresponding oligomers in vivo. Molecular genetic approaches are leading to an understanding of the regulatory genes that control proanthocyanidin biosynthesis, and this information, together with increased knowledge of the enzymes specific for the pathway, will facilitate the genetic engineering of plants for introduction of value-added nutraceutical and forage quality traits.     

Changes in grape seed polyphenols during fruit ripening

The quantity and characterization of extracted flavan-3-ol monomers and procyanidins was determined in seeds from Vitis vinifera cv. Cabernet Sauvignon berries, over the course of ripening and at different levels of vine water status. The per berry extractive yield of all polyphenols decreased with maturity, and followed second-order kinetics. The flavan-3-ol monomers decreased most rapidly, followed by the procyanidin extension units and finally, the terminal units. The relative proportion of procyanidin extension units did not vary with maturity. During fruit ripening, the mean degree of polymerization of extracted procyanidins is unchanged when analyzed intact by HPLC, but decreases by thiolytic degradation. The proportion of extracted procyanidins resistant to acid catalyzed thiolysis increased with maturity. Changes in vine water status affected polyphenol amounts, indicating that cultural practices can be used to influence composition. Oxidation of the seed polyphenols during fruit ripening, could explain these observations.     

不同提取溶剂和方法组合从落叶松毛虫蛹中提取的脂肪酸成分和含量的比较

落叶松毛虫Dendrolimus superans (Butler)蛹个体较大, 具有很高利用价值。为明确东北落叶松毛虫蛹中脂肪酸成分, 探讨最佳提取溶剂和提取方法的组合, 分别以正己烷、 石油醚和乙醚为提取溶剂, 结合超声波振荡萃取法、 索氏萃取法及溶剂萃取方法热浸和冷浸4种提取方法提取落叶松毛虫蛹油, 并采用毛细管色谱-质谱法分析提取物的脂肪酸种类和相对含量。结果表明： 正己烷溶剂与4种提取方法的组合中, 溶剂萃取热浸法提取率最高, 为25.60%。索氏萃取及溶剂萃取方法热浸和冷浸均检测到10种脂肪酸, 正己烷-超声波振荡萃取组合检测到9种脂肪酸。石油醚溶剂与4种提取方法的组合中, 索氏萃取提取率最高, 为29.31%, 均检测到10种脂肪酸。乙醚溶剂与4种提取方法的组合中, 溶剂萃取冷浸法提取率最高, 为29.11%, 检测到的脂肪酸种类为溶剂萃取冷浸法（13种）＞索氏萃取法（12种）＞溶剂萃取热浸法（11种）＞超声波振荡萃取法（9种）。在检测到的总脂肪酸中, 63%以上为不饱和脂肪酸, 其含量受提取溶剂和方法的影响不大。因此, 适合东北落叶松毛虫蛹中脂肪酸提取的最佳组合为石油醚溶剂 索氏萃取法。     

Resveratrols in Grape Berry Skins and Leaves in Vitis Germplasm

Background

Resveratrol is an important stilbene that benefits human health. However, it is only distributed in a few species including grape and is very expensive. At present, grape has been an important source resveratrol. However, the details are scarce on resveratrol distribution in different Vitis species or cultivars.

Methodology/Principal Finding

The composition and content of resveratrols were investigated by HPLC for assessing genotypic variation in berry skins and leaves of 75 grape cultivars, belonging to 3 species and 7 interspecific hybrids. Trans-resveratrol, cis-piceid and trans-piceid were detected in berry skins and leaves, but cis-resveratrol was not. Resveratrol content largely varied with genetic background as well as usage. In most cultivars, total resveratrol including the above three compounds was higher in berry skins than leaves. In berry skins of most cultivars and leaves of almost all cultivars, cis-piceid was the most abundant resveratrol; trans-resveratrol and trans-piceid were minor components. Some specific cultivars were found with extremely high levels of trans-resveratrol, cis- piceid, trans-piceid or total resveratrols in berry skins or leaves. In skins and leaves, rootstock cultivars had a higher content of total resveratrols, and the cultivated European type cultivars and their hybrids with V. labrusca had relatively low totals. There were no significant correlations of the amounts of total resveratrols or any individual resveratrol between berry skins and leaves. All 75 cultivars can be divided into four groups based on the composition of resveratrols and their concentration by principal component analysis.

Conclusion

Resveratrol content of grape berries and leaves varied largely with their genetic background and usage. Rootstock cultivars had a higher content of total resveratrols than the other germplasm. Total resveratrols were lower in leaves than berry skins in most cultivars. Cis-piceid was the most abundant resveratrol in most cultivars, and trans-res and trans-pd were minor components.     

Comparison of soluble proteins in juice and wine from Koshu grapes

Proteins were separated from Koshu grape juice and wine by precipitation with ammonium sulfate. The protein fractions were further fractionated by gel electrophoresis and gel isoelectric focusing, followed by amino acid analyses. The juice contained more than eleven protein fractions with molecular weights between 13,000 and 65,000, and their isoelectric points were between 3.6 and 10.5. The wine also contained more than eleven protein fractions with molecular weights between 21,000 and 65,000, while their isoelectric points were between 3.6 and 11.0. All the juice proteins and some major wine proteins were glycoproteins. The same three protein fractions were present in both juice and wine. The other juice proteins were lost during wine-making and thus, were not detected in the wine. About half of the proteins detected in the wine were not observed in the juice. Some juice proteins were bound to the flavonoid phenolics extracted from the wine and were removed as insoluble precipitates. There was specific interaction between wine flavonoids and juice proteins.     

Proteomic analysis of β-1,3-glucanase in grape berry tissues

Grape berries are considered recalcitrant materials in proteomic analysis, because berry tissues contain large amounts of secondary metabolites, especially phenolic compounds, which severely interfere with protein extraction and electrophoresis separation. We report hereby a PVPP/TCA-based protein extraction protocol for grape berries. Phenolic compounds in berry extracts were removed with repeated PVPP cleanups, and proteins were recovered with TCA precipitation. Protein resolution in 2-D gels was gradually improved with the increase of PVPP cleanup steps. By the protocol, about 760 protein spots of berry tissues were clearly resolved in 2-D gels with CBB staining. This protocol was also used to analyze β-1,3-glucanase (EC 3.2.1.39) in berry tissues. An anti-synthetic peptide antibody was prepared against 15 amino acid sequence residing on the surface of β-1,3-glucanase molecule. It detected two major spots in 2-D blots of berry extracts. The spots were identified by MALDI-TOF analysis as β-1,3-glucanase. The present study validates that β-1,3-glucanase is present in higher abundance in berry skins than in pulps, and in red berries than in white berries. Therefore, β-1,3-glucanase displays a tissue-specific expression. The preferential accumulation of β-1,3-glucanase in skins may be relevant to berry ripening.     

葡萄籽中原花青素的提取及应用现状

原花青素（proanthocyanidins,PC)是目前国际上公认的清除人体内自由基最有效的天然抗氧化剂,广泛分布于多种天然植物中。阐述了葡萄废弃物中原花青素的功能,分析了其应用开发现状。结合常用的提取方法,并综合国内外关于原花青素的研究进展,对葡萄籽中原花青素提取的工艺参数进行优化,从而得出葡萄籽中原花青素最优提取方案。以期为葡萄籽的全面利用和原花青素的工业化生产提供科学依据,使原花青素拥有更广泛的应用。     

Metabolism of phenolic compounds in <Emphasis Type="Italic">Vitis riparia</Emphasis> seeds during stratification and during germination under optimal and low temperature stress conditions

We studied the alterations in phenolic compounds in grape seeds during their stratification and germination under optimal conditions (+25 °C) and at low temperature (+10 °C). Biological materials in the study were seeds of Vitis riparia. Phenolic compounds were extracted from defatted seeds using 80 % methanol or 80 % acetone. The content of total phenolics was determined with the Folin-Ciocalteau reagent, while the content of tannins was determined by vanillin assay and the protein (BSA) precipitation method. The RP-HPLC method was used to determine phenolic compounds (phenolic acids, catechins) in the extracts. High amounts of tannins, catechins, gallic acid and lesser amounts of p-coumaric acid were found in the seeds. The content of total phenolics in acetone extracts was higher than that obtained using methanol. The amounts of phenolic acids and tannins found in V. riparia seeds after stratification were much lower. It may confirm a possible role of these compounds in dormancy of V. riparia seeds. After 72 h of low temperature treatment, inhibition of grape root growth and biochemical changes in seeds were detected. The chilling stimulated increased accumulation of some phenolic compounds (free gallic acid and catechins) in the seeds. These substances can protect plants against some abiotic stressors.