Effect of the prefermentative addition of copigments on the polyphenolic composition of Tempranillo wines after malolactic fermentation

The influence of the prefermentative addition of copigments and different winemaking technologies on the polyphenolic composition of Tempranillo red wines after malolactic fermentation was studied. Six experiments dealing with the prefermentative addition of caffeic acid, rutin, (+) catechin, white grape skin tannin, white grape seed tannin and control wines were realised. Three different winemaking technologies (traditional vinification, prefermentative cold maceration at 6–8 °C and cold soak at 0–2 °C with dry ice) were studied. Prefermentative addition of copigments increases anthocyanin copigmentation reactions and produces wines with a greater colour, a higher anthocyanin concentration, a superior contribution of anthocyanins to the colour of the wine, a superior percentage of tannins polymerised with polysaccharides and less astringency. Cold prefermentative maceration increases the extraction of polyphenols, the anthocyanin copigmentation reactions and the polymerisation reactions between tannins and polysaccharides. The effectiveness of the combination of copigments and prefermentative maceration treatments was demonstrated by the increase of the concentration of the polyphenolic compounds.     

不同皮渣浸渍发酵时间对葡萄酒中缩合单宁构成及感官品质的影响

为明确不同皮渣浸渍时间对葡萄酒中缩合单宁的影响,以赤霞珠和西拉为材料,进行不同浸渍发酵时间处理,对葡萄皮和葡萄籽以及葡萄酒中缩合单宁的含量、组成、缩合单宁以及相关口感指标等进行了分析。结果表明,不同葡萄品种中缩合单宁的初始含量、聚合度及没食子酰化率都有显著差异（P<0.05）。葡萄皮中缩合单宁的平均聚合度显著高于葡萄籽（P<0.05）,而葡萄皮缩合单宁的没食子酰化率则显著低于葡萄籽缩合单宁（P<0.05）。葡萄皮和葡萄籽中缩合单宁组成的最大差异是葡萄籽缩合单宁中不含有（?）-表棓儿茶素亚单元,而且末端单元主要是由（+）-儿茶素、（?）-表儿茶素和（?）-表儿茶素没食子酸酯组成。皮渣浸渍时间对葡萄酒中缩合单宁的组成及含量都有明显影响。随着浸渍时间的延长,葡萄酒中缩合单宁的总含量呈上升趋势,而平均聚合度则呈下降趋势。不同品种的葡萄酒之间缩合单宁含量也存在显著差异（P<0.05）,这与不同葡萄品种中酚类物质的可浸提率有关。葡萄酒中葡萄皮缩合单宁的占比一直显著高于籽粒缩合单宁的占比（P<0.05）,说明葡萄皮中缩合单宁比葡萄籽缩合单宁更容易浸提到葡萄酒中。相对于苦味和酸味,不同浸渍时间处理对葡萄酒的涩味影响更为显著（P<0.05）,综合考虑酒体的丰满度和口感的平衡,皮渣浸渍时间选择14 d左右更好一些。     

Effect of Wine Maceration Enzymes on the Extraction of Grape Seed Proanthocyanidins

Proanthocyanidins, which are located in the skins and seeds of grapes, are important for red wine quality since they participate in astringency, bitterness and colour stabilization. Maceration enzymes have long been used to improve the extraction of phenolic compounds from skins, but their role in seed degradation and the release of seed phenolic compounds is not well known. This contribution describes the effect of different pure enzyme activities (xylanase, cellulase, polygalacturonase and pectinmethylesterase) on the release of proanthocyanidins from seeds of Monastrell and Cabernet Sauvignon grapes. The results demonstrate that some enzymes, especially polygalacturonase and cellulase, favour the degradation of seed cell walls, promoting the diffusion of proanthocyanidins, although differences due to grape variety also exist.     

Astringency sub-qualities of red wines and the influence of wine–saliva aggregates

Astringency is a sensory attribute, related to the quality and mouthfeel of red wines. However, the origin of astringency sub-qualities, such as the typical drying astringency found in immature grapes, is still unknown. Astringency of red wines with similar tannin content but different astringency sub-qualities, from different harvest dates, is studied. Astringency was characterised in terms of friction coefficient, polyphenol content, sensory analysis and tannin/salivary–proteins aggregates characterisation. A different evolution during ripening was found for both Cabernet Sauvignon and Carménère, and tannin–protein aggregates showed differences in size, shape and surface. The velvety sub-quality appears to be related to aggregates with low precipitation, and with specific surface characteristics as roundness and Feret diameter. Results from this work propose an effect of aggregates on sensory perception and opens the possibility to explore their effect on oral lubrication.     

Influence of skin maceration time on the proanthocyanidin content of red wines

This paper studies the influence of different maceration times (5, 10 and 20?days) during the elaboration of Monastrell, Syrah and Cabernet Sauvignon wines on the proanthocyanidin composition and sensory characteristics of the resulting wines. Significant differences were found between wines elaborated with different maceration times. The different maceration times affected the qualitative and quantitative proanthocyanidin composition of the resulting wines, the total proanthocyanidin content increasing with the maceration time. The percentage of skin-derived proanthocyanidins was always higher than that of seed-derived proanthocyanidins for all the maceration time assayed, although the contribution of seed proanthocyanidins to wine composition increased for the longest maceration time. However, the study also shows that differences exist between wines elaborated with the same maceration time but with different varieties, indicating the importance of two factors, the initial concentration of grape phenolic compounds and their extractability, on the final concentration of wine proanthocyanidins. In this way, the wines obtained from Syrah had the highest proanthocyanidin content compared with the corresponding wines from Cabernet Sauvignon or Monastrell, even though Syrah grapes presented the lowest proanthocyanidin content in skins and similar seed proanthocyanidin content to Cabernet and Monastrell grapes.     

The maceration process during winemaking extraction of anthocyanins from grape skins into wine

The rate of anthocyanin extraction from skins of Monastrell grapes into wine during the maceration process has been studied by following anthocyanin accumulation in wine and its decrease in crushed skins. The most important changes occurred during the first 7 days of maceration; the following 7 days saw very little variation in the levels of the anthocyanins found in the wine or the crushed skins. The anthocyanin profile of the wines was quite different from that of the grape skins, whereas the crushed grape skins had a profile very similar to the profile of the grape skins at the time of harvest. Any differences in the proportions of the different anthocyanins found in Monastrell grapes and wines cannot therefore be attributed to different rates of extraction for each of the anthocyanins during winemaking. Other explanations, such as degradation or yeast cell wall adsorption, must be sought.     

不同浸渍工艺对夏黑葡萄醪理化指标及颜色的影响

以热浸渍法、冷浸渍法、常温浸渍法为基础,通过部分添加不同浓度的二氧化硫和果胶酶,探究不同浸渍工艺对葡萄醪中单宁、总酚含量、pH值、色度、色调等指标的影响。结果表明,冷浸渍法（浸渍温度4 ℃、二氧化硫添加量50 mg/L、浸渍时间13 h）浸提时,葡萄醪中单宁含量6.884 mg/L,总酚含量122.332 mg/L,pH值3.85,色调最低,色度最高;常温浸渍法（浸渍温度20 ℃、二氧化硫添加量50 mg/L、浸渍时间13 h）浸提时,葡萄醪中单宁含量7.612 mg/L,总酚含量134.756 mg/L,pH值3.85,色调最低,色度最高;热浸渍法（浸提温度80 ℃,浸渍时间100 min）浸提时,葡萄醪中单宁含量23.451 mg/L,总酚含量264.688 mg/L,pH值3.43,色调最低,色度最高。     

Application of the dual attribute time‐intensity (DATI) sensory method to the temporal measurement of bitterness and astringency in sorghum

Bitterness and astringency are attributes generally cited as the cause of tannin sorghums being unpalatable. The objective here was to determine the effect of sorghums with varying tannin content on bitterness and astringency simultaneously using dual attribute time‐intensity (DATI). A trained panel assessed bitterness and astringency of bran infusions of tannin and tannin‐free sorghums. In both sorghum types, bitterness developed and reached maximum intensity faster (T_max 22.5 s; P < 0.001) than astringency (27.9 s). The duration of the astringent sensation (D_tot 69.9 s) lasted longer than bitterness (66.3 s). Overall, the temporal parameters for bitterness distinguished infusions from tannin and tannin‐free sorghums slightly more clearly than those for astringency. The research established that, for sorghum, bitterness and astringency are related. The DATI method also revealed that panellists’ perceptions of the time course of bitterness and astringency differ.     

Microwave Maceration of Pinot Noir Grape Must: Sanitation and Extraction Effects and Wine Phenolics Outcomes

Pinot noir grapes have a unique phenolic profile which can impinge on the extraction and stabilisation of compounds such as anthocyanins and tannins which contribute to the colour and mouthfeel of red wine. This study examined the concentration of phenolic compounds in Pinot noir grape must and wine following application of a novel microwave maceration treatment for red grape must. Microwave maceration was shown to be highly effective for extraction of phenolics from grape solids into grape juice. When juices were fermented to wine, ultraviolet–visible spectrophotometry showed microwave maceration was associated with significantly higher concentrations of total phenolics, anthocyanin, tannin and pigmented tannin in wine at 18 months bottle age, compared with control wine. Mean tannin concentration in microwave treatment wine was 0.60 gm/L at 18 months, compared with 0.14 gm/L in control wine. The microwave treatment was also associated with a substantial and rapid decrease in the grape-associated yeast population, compared with control maceration, and a shorter lag phase at the outset of alcoholic fermentation. Based on this study, microwave maceration warrants further investigation as a potential industrial-scale application in red winemaking.     

蓝靛果单宁的提取及对酵母发酵能力的影响

为确定酵母菌发酵蓝靛果果汁中的最适单宁含量,采用单因素实验及正交试验优化超声辅助法提取蓝靛果单宁工艺,将此条件下获得的单宁粗提液纯化、浓缩后得到单宁酸样品。将其添加到模拟蓝靛果果汁中,研究不同浓度单宁酸对酵母菌的影响,并验证最适单宁含量对发酵蓝靛果果汁的影响。结果表明,蓝靛果单宁最优提取条件为:乙醇体积分数50%,料液比1:60（g/mL）,超声温度50 ℃,超声时间40 min,此条件下单宁得率为14.68%。浓度为400 mg/L单宁酸模拟果汁中酵母菌的生长趋势良好,稳定期内酵母菌活性最高。与原发酵果汁相比,采用单宁酶处理后,最适单宁含量的发酵果汁中酒精度及总酸含量分别提高84.21%和14.58%,残糖含量及涩度值分别降低57.91%和86.32%,总酯含量提高38.45%。该含量单宁对酵母菌的发酵效果具有明显促进作用,果汁涩感降低且酸甜适中,果香及发酵香浓郁。     

Influence of grape variety on the extraction of anthocyanins during the fermentation on skins

The extraction of anthocyanins in the fermentation on skins is conditioned by several factors, such as the grape composition and the enological practices. In this work, the varietal effect on the anthocyanins extraction was studied, considering a series of fermentation on skins of Tannat, Cabernet-Sauvignon and Merlot. The different anthocyanic structures have a different diffusion in the must, at least during first stages of maceration. The decrease of the proportions of cyanidin and peonidin during the first days, with a consequent increase of the malvidin and petunidin proportions was verified. The coumarates proportions increased after the first day of maceration in all the musts. However, the definitive proportions of each anthocyanic form are reached rapidly and remain constant after the second or third day of maceration. The anthocyanic fingerprint of the young wines obtained in classical fermentation on skins is characteristic of each grape variety, although their evolution follows the general tendencies indicated.     

Autochthonous white grape pomaces as bioactive source for functional jams

Seeds and skins from grape pomaces of Pecorello and Mantonico cv underwent extraction (ultrasound–assisted or maceration), in order to obtain added-value ingredients for the production of a functional pear jam. The antioxidant features of the extracts were tested by in vitro colorimetric assays. Among seeds, Mantonico by maceration (MSC) showed the best results, as well as Mantonico by ultrasound-assisted extraction (MBs) among skin extracts. The selected extracts were fully characterised by NMR and MS techniques, confirming the presence of many polyphenols, flavonoids and tannins among others. Pectin was then derivatised by the grafting procedure with the active molecules of MBs and MSC. The latter produced the best antioxidant polymer also without toxicity evaluated using Caco-2 cells and was used for the jam preparation. The functional pear jam showed improved antioxidant performances in comparison with its non-functional counterparts as well as its maintenance over time (15 days).     

Phenolic content and antioxidant potential of macerated white wines

Influence of maceration on phenolic content and antiradical activity was analyzed in fourteen white wines from Italian region Friuli–Venezia Giulia and Croatian region Istria. Total phenols were determined by Folin–Ciocalteu reagent, twelve individual polyphenols were determined by high-performance liquid chromatography and antiradical activity was determined using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH^·). The experiments showed that the maceration process increases significantly the amount of total phenols and inhibition of DPPH^·. Furthermore, a high synergistic activity of individual phenols was observed. The strongest inhibition of DPPH^· and the highest amount of total phenols were obtained for 800 Bianco, a blending macerated wine made from 3 white wine varieties. Our study shows that the antioxidant potential of white grape phenols can be preserved during wine processing. The maceration step allows the extraction of phenolic compounds from grape skins, seeds and stalks, resulting in phenol-rich white wine with strong antioxidant properties.     

Analysis of tannins in seeds and skins of Shiraz grapes throughout berry development

The flavan-3-ol and proanthocyanidin composition of both seeds and skin of Vitis vinifera L. cv. Shiraz grapes was determined by reversed-phase HPLC after acetone extraction and acid-catalysis in the presence of excess phloroglucinol. Samples were taken at weekly intervals from fruit-set until commercial harvest. The main period of proanthocyanidin accumulation in grape seeds occurred immediately after fruit-set with maximum levels observed around veraison. Over two seasons there was variation in both the timing and content of proanthocyanidins in seeds. In skin, proanthocyanidin accumulation occurred from fruit set until 1–2 weeks after veraison. Proanthocyanidin subunit composition was different in seeds and skin and changed during berry development but the mean degree of polymerisation of the tannin polymers in skins was higher than in the seeds at all stages of berry development. Proanthocyanidin levels in both seeds and skin decreased between veraison and harvest. Additional proanthocyanidin subunits were released when the residues remaining after acetone extraction were subjected to direct acid-catalysis in the presence of phloroglucinol. In the seeds, these accounted for much of the post-veraison decrease, but not in grape skin. At harvest, 75% of extractable berry proanthocyanidin was in the seeds. Accumulation of proanthocyanidins in the seeds appears to be independent of that in the skins, but in both tissues synthesis occurs early in berry development and maximum levels are reached around veraison.     

不同处理对磨盘柿冷藏及货架期品质与生理的影响

以磨盘柿为试材,用浓度为1.0 μL/L的1-MCP处理,用高浓度CO2(85%~90%)处理24 h,探究不同处理方式(CO2脱涩、1-MCP处理后CO2脱涩、1-MCP与CO2脱涩同时处理)对冷藏及冷藏后货架期果实的品质与生理影响。结果表明,与CO2脱涩相比较,1-MCP处理后CO2脱涩可以有效降低柿果呼吸强度,抑制乙烯生成速率、柿果色泽的改变,延缓柿果质地的降低,维持果实营养物质(TSS、TA及Vc含量)在较高水平,有效减缓了挥发性香气成分的减弱。但1-MCP与CO2脱涩同时处理却加速了果实成熟且贮藏后期差异显著(P<0.05)。因此,柿果经1-MCP处理后再高浓度CO2脱涩不仅可脱涩还具有较好的保鲜效果。     

Evaluation of sensory parameters of grapes using near infrared spectroscopy

Grape seed and skin sensory parameters are important characteristics in making decisions concerning the optimal harvest time and producing high-quality red wines. The potential of near infrared spectroscopy to determine several sensory parameters of seeds and skins was evaluated. Taste (sourness), texture (astringency, tannic intensity, dryness and hardness), visual (colour) and olfactory (intensity and type of aroma) attributes were considered. Calibration models were performed by modified partial least squares regression. The differences between sensory analysis and NIRS analysis in external validation were lower in the case of seeds; they were between 4.5% for hardness and 8.7% for colour. For the skins, differences in external validation were between 9.8% for tannic intensity and 13.7% for astringency. The results obtained show that NIRS technology has considerable potential for predicting the above sensory attributes.     

Interaction of phenolic compounds with bovine serum albumin (BSA) and α-amylase and their relationship to astringency perception

The ability of grape seed extracts to bind to bovine serum albumin (BSA) and α-amylase was studied by fluorescence quenching of protein intrinsic fluorescence and nephelometry. The influence of grape seed ripeness on astringency was also evaluated. From the spectra obtained, the modified Sterm-Volmer (K(app)) and the bimolecular quenching constants were calculated. Results showed that grape seed extracts had good affinity for proteins. The association strength of tannin-protein interactions varied with changes in tannin structure associated with the degree of ripeness affecting the binding/quenching process. In all cases studied, higher values of K(app) were obtained in samples at harvest which have greater ability to bind to proteins than have samples at post-veraison time. Nephelometric assays show the same trend as do fluorescence quenching studies. A possible explanation for this is that, as seeds ripen, their tannins increase in molecular mass, which relates to an increase in hydrophobicity of the molecules, and this increases protein affinity. However, that is contrary to the reported decrease in astringency of grape seeds during maturity. This indicates that tannin-protein interactions are not the only explanation for the complex sensations of astringency of grape seeds.     

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.     

冷浸渍及单宁处理提升赤霞珠葡萄酒的品质

为研究冷浸渍及单宁处理对赤霞珠葡萄酒颜色稳定性的影响,以和硕产区赤霞珠葡萄酒为对象,通过发酵前赤霞珠葡萄冷浸渍(8℃下,4 d、8 d、12 d)及发酵过程中添加不同浓度的VR单宁(TANIN VR COLOR,0.10、0.20、0.30 g/L)处理,对赤霞珠葡萄酒的基础理化指标、酚类物质以及CIELab颜色参数进行分析。研究发现,冷浸渍处理(4 d、8 d、12 d)与对照组相比总酸含量分别提升了17.63%、15.70%、26.96%,经过不同浓度(0.10、0.20、0.30 g/L)VR单宁处理的葡萄酒总酸含量分别增加了1.33%、16.74%、13.04%;随着冷浸渍时间的延长,葡萄酒中的单宁和总酚的含量有所增加,而花色苷含量在冷浸渍8 d时达到了最大值111.04 mg/L,添加0.20 g/L VR单宁的酒样单宁、总酚及总花色苷含量分别高于对照组28.40%、26.78%、25.42%;冷浸渍8 d的葡萄酒a^*值和Cab值最高,分别为38.85和42.29,而添加了0.20 g/L VR单宁的葡萄酒b^*值和Hab值与对照组相比分别降低了1.61%、1.84%。综合比较表明,冷浸渍8 d和添加0.20 g/L VR单宁的工艺处理可以有效地提升赤霞珠干红葡萄酒的颜色稳定性。     

感官评定方法确定麻竹笋苦涩味物质成分及与口感的关系

通过分析测定麻竹笋苦涩味物质含量与感官评定方法确定竹笋苦涩味物质成分及与口感的关系。麻竹鲜笋在100℃纯净水中分别进行0、30、90、150 s和420 s 5个时间梯度水煮处理,并测定煮后笋汤、笋渣的可溶性单宁、草酸和游离苦味氨基酸(Phe、Val、Arg、Met和Leu)含量,感官评定小组对其涩味、苦味强度评定,并通过对食品级草酸、单宁标准样品配制的不同质量浓度溶液进行苦涩味感官评定,建立单宁、草酸、单宁和草酸混合液的质量浓度与滋味强度的特征曲线函数。结果表明,影响麻竹笋苦涩味的主要物质是可溶性单宁,竹笋苦味和涩味均与单宁含量呈极显著关系,相关系数分别达0.896和0.867;竹笋涩味与草酸含量呈显著关系,相关系数为0.448,而竹笋苦味与草酸含量无显著关系;竹笋苦涩味与游离苦味氨基酸含量均无显著关系。利用单宁特征曲线函数对竹笋苦涩味偏重的成因进行了分析,对9个笋渣、笋汤的分析结果表明,单宁特征曲线函数对竹笋涩味的解释程度达60.6%~136.4%,对竹笋苦味的解释程度达63.4%~132.0%,较高的可溶性单宁含量是引起麻竹笋苦涩味偏重的主要原因。