Effects of viscosity on the bitterness and astringency of grape seed tannin

To examine the separate effects of viscosity and sweetness on astringency, aqueous solutions of grape seed tannin (GST) were thickened with carboxymethyl cellulose (CMC) from 2 to 45 cP (experiment 1) or sweetened with 0 to 1.8 g/L aspartame (experiment 2). Trained subjects continuously rated astringency and bitterness in duplicate. Subjects were categorized by the salivary flow induced by citric acid and ability to taste n-propyl thiouracil (PROP). In experiment 1, maximum intensity and total duration of astringency were significantly decreased as viscosity rose, although time to maximum intensity of astringency was not affected. Maximum intensity and total duration of bitterness were not significantly affected by increasing viscosity; however, the onset of bitterness was significantly delayed. In experiment 2, increasing sweetness had no affect on any astringency parameter, although maximum intensity of bitterness was significantly decreased. Neither PROP nor salivary flow-status had any effect on perception of bitterness or astringency in either experiment.     

Influence of texture on the temporal perception of sweetness of gelled systems

The aim of this work was to study how the texture of two hydrocolloid gelled systems with different mechanical properties – κ-carrageenan and gellan gum – sweetened with two sweeteners with different sweetening power – sucrose and aspartame – influence the temporal perception of sweetness using a time–intensity test. The results show that the different aspects of temporal perception of sweetness of hydrocolloid gels were related to their mechanical properties in different ways. Maximum sweetness intensity was closely related to the amount of deformation required to break the network and with its resistance to deformation. Meanwhile resistance to rupture was also an important factor influencing the variation in the rate of intensity decrease. The time needed to reach maximum sweetness intensity was only dependent on sweetener concentration.     

Effect of gel texture and sucrose spatial distribution on sweetness perception

Layered gels differing in mechanical and breakdown properties (soft, medium and hard gels) and in the distribution of sucrose in the matrix (homogeneous and inhomogeneous distributions) were used to investigate the effects of texture and spatial distribution of sucrose on sweetness perception. Rating tests, 2-Alternative forced choice tests and time-intensity analysis were performed to compare the sweetness of soft, medium and hard gels with homogeneous and inhomogeneous distributions of sucrose. Results showed that all gels with an inhomogeneous distribution of sucrose were perceived sweeter than gels in which sucrose was homogeneously distributed. This indicates that the enhancement of sweetness by an inhomogeneous distribution of sucrose does not depend on the texture of the gel matrix. Furthermore, the time-intensity profiling showed that soft gels, which had low values of fracture strain and fracture stress and broke down in a large number of small fragments upon chewing, had the highest sweetness intensity. The time required to reach the maximum sweetness intensity tended to be shorter in soft gels. These findings suggest that the breakdown behavior of the gel matrix during oral processing affects the perception of sweetness of layered gels.     

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.     

Sensory astringency of 5-O-caffeoylquinic acid,tannic acid and grape-seed tannin by a time-intensity procedure

The astringency of 5-0-caffeoylquinic acid (5-CQA) was investigated by a time-intensity technique alongside those of tannic acid and grape-seed tannin. Significant differences were recorded between 5-CQA and the other phenolic solutions for the intensity of the response, its persistence (or overall duration), its fading (or decline from maximum intensity to zero), and for the total gustatory response (or total area under the time-intensity curve). In each case, 5-CQA elicited a weaker response than either grape-seed tannin or tannic acid. Nevertheless, overall, panellists recorded a response for 5-CQA that was qualitatively similar to those for tannic acid and grape-seed tannin, which are traditionally accepted as astringents. This phenomenon occurred, despite 5-CQA having a molecular mass of 354 and containing only one 1,2-dihydroxyphenyl residue, which would place it outwith the traditional definition of an astringent. The requirements appropriate to vegetable tanning may not therefore apply to oral astringency.     

葡萄酒中单宁涩感评价及结构分析研究进展

单宁是红葡萄酒中的重要成分,对红葡萄酒的口感、颜色、稳定性等都有着重要的影响。该文介绍了单宁的涩感评价方法（感官评价、蛋白质沉淀法、电子舌）及结构分析方法（色谱技术、核磁共振技术、质谱技术、基质辅助激光解吸附技术）的研究进展,并提出了今后的研究方向。     

葡萄籽油的添加对山核桃油抗氧化能力改善的研究

以山核桃油为主体,通过抗氧化剂BHT、VE、Vc及葡萄籽油的,对山核桃油的氧化稳定性进行研究.研究表明:当葡萄籽油的添加量为6％时,油脂的OSI值最大,相比较0.02％Vc、0.02％ VE及0.02％BHT的抗氧化剂添加对山核桃油抗氧化性影响要大,因此,葡萄籽油可以作为一种新型的天然抗氧化剂,对延长山核桃的货架保质期...     

Evaluation of aglianico grape skin and seed polyphenol astringency by SDS–PAGE electrophoresis of salivary proteins after the binding reaction

SDS–PAGE electrophoresis and densitometry analysis were carried out to evaluate the reactivity of Aglianico red grape skin and seed polyphenols with human salivary proteins in order to find a method able to assess their astringency. Analysis of the supernatant obtained after a tannin/human salivary protein binding assay and sensorial analysis showed that four proteins, lactoferrin, PRPbg1, PRPbg2 and α-amylase, were the proteins best able to distinguish tannin solutions characterised by different levels of astringency.     

Effect of heating conditions of grape seeds on the antioxidant activity of grape seed extracts

This study was carried out to evaluate the effect of heating and physical conditions of grape seeds on the antioxidant activity of their extracts. Two forms of grape seeds, whole and powdered forms, were heated at four different temperatures −50, 100, 150 and 200 °C. After heating, grape seeds were extracted with 70% ethanol (0.1 g grape seed/10 mL of 70% ethanol), and total phenol contents (TPC), radical scavenging activity (RSA) and reducing power of the extracts were determined. Thermal treatment of grape seed increased the antioxidant activity of extracts. The maximum TPC and RSA of whole grape seed extract (WGSE) were achieved when the seeds were heat-treated at 150 °C for 40 min, while that of powdered grape seed extract (PGSE) were at 100 °C for 10 min, and were greater than that of the non-treated control. Also, the reducing powers of WGSE and PGSE slightly increased at the conditions. According to the GC-MS analysis, several low-molecular-weight phenolic compounds such as azelaic acid, 3,4-dihydroxy benzoic acid, and o-cinnamic acid were newly formed in the WGSE heated at 150 °C for 40 min. There were slight differences in the kinds of phenolic compounds between non-heated and heated GSE. In HPLC analysis, the contents of gallocatechin gallate and caffeine in GSE significantly increased by heat treatment. These results indicated that antioxidant activity of GSE was affected by heating conditions (temperature and time) and physical conditions of grape seeds at the time of heat treatments.     

精炼对山葡萄籽油品质的影响

以酸热法提取得到的山葡萄籽原油为原料,研究了山葡萄籽油精炼前后的品质变化。测定山葡萄籽油精炼前后感观品质和理化指标、VE含量、氧化稳定性、微量元素含量、脂肪酸组成及含量的变化。结果表明:精炼山葡萄籽油较原油在感官品质与理化指标上都有很大提升,氧化稳定性提高,酸值(KOH)由(16. 85±0. 016) mg/g降至(0. 21±0. 013) mg/g;精炼对山葡萄籽油中微量元素含量影响不大,但V_E含量明显减少,从(66. 18±0. 21) mg/100 g降至(43. 65±0. 16) mg/100 g;脂肪酸组成变化不大,反式脂肪酸含量由(0. 07±0. 003)%增加至(0. 31±0. 004)%。     

Review: Condensed tannin and grape cell wall interactions and their impact on tannin extractability into wine

It has been suggested that tannin extraction from grape berries into wine is limited by tannin binding to cell walls. Here we review the current state of knowledge and identify gaps in research that would enable characterisation of these interactions. Such characterisation could improve tannin extraction management in winemaking. The work identified in this review supports the hypothesis that tannin–cell wall interactions are formed by hydrogen bonding and hydrophobic interactions with the binding capacity of the cell walls influenced by tannin and polysaccharide structure and composition. Cell wall changes during berry development may increase the tannin-binding capacity of cell walls, while tannin structure may also influence its affinity for cell wall material. This review also identifies the need to investigate cultural and environmental factors that affect tannin and polysaccharide composition, to characterise the tannin-binding capacity of cell walls and to develop methods for assessing tannin-binding capacity of fruit prior to harvest. It is envisaged that a detailed understanding of tannin interactions with other components in the grape would lead to a predictive model for extractability of condensed tannins into wine.     

Effect of temperature on oxidation kinetics of walnut and grape seed oil

The effects of temperature on the oxidation of walnut oil (WO) and grape seed oil (GSO) were investigated. Both oils were stored at 25, 40, 60, and 80°C for 60, 30, 12, and 6 day, respectively. Degree of oxidation was measured in terms of peroxide value (POV), conjugated dienoic acid (CDA) value, and p-anisidine value (p-AV). The rates of increase in POV, CDA, and p-AV in both oils were strongly dependent on storage temperature. The induction period (IP) decreased gradually with increasing storage temperature in both oils. WO showed shorter IPs (23.0, 9.2, and 1.0 day at 25, 40, and 60°C, respectively) than those of GSO (41.5, 12.0, and 1.8 day at 25, 40, and 60°C, respectively), indicating the higher susceptibility of WO to oxidation. The activation energy (Ea) for the IP of WO and GSO autoxidation was similar (75.87 and 75.66 kJ/mol, respectively), revealing similar temperature dependence for autoxidation in WO and GSO.

     

葡萄籽提取物对健康人体尿液的代谢组学研究

目的:采用1H-NMR代谢组学技术研究口服葡萄籽提取物后人体尿液中内源性代谢产物的变化规律。方法:选择16名健康男生随机平均分成两组,即试食组（A）和对照组（B）。试食组每人每天口服葡萄籽提取物软胶囊2粒,连续14d,对照组连续服用安慰剂14d。分别收集试食组及对照组服药前（0d）和服药后（14d）的晨尿,运用1H-NMR代谢组学技术分析尿液中内源性代谢产物的变化及其规律。结果:与对照组相比,服药14d后,试食组人体尿液中乳酸水平下降,肌酐水平上升,且具有显著性差异（p<0.05,0.01）;结论:葡萄籽提取物（GSE）对人体尿液中内源性代谢产物的调节作用显著,涉及能量代谢和氨基酸代谢通路,对能量代谢的调节尤为显著,是一种很好的运动营养补充剂。1H-NMR代谢组学技术在运动科学研究中的应用前景广阔。      

The role of acidity,sweetness, tannin and consumer knowledge on wine and food match perceptions

The purposes of this study were to (1) explore significant differences in perception of match for a variety of food and wine styles; (2) evaluate the impacts of wine sweetness level, wine acidity level, and wine tannin level on perception of match; and (3) investigate the impact of food and wine expertise on perceived level of match. The highest perceived wine matches for each food item were: Sauvignon Blanc and chêvre, Chardonnay and brie, Cabernet Sauvignon and spicy Italian salami, and Port and milk chocolate. Wine sweetness, acidity, and tannin levels all significantly impacted the level of match with certain food items. Food and wine expertise also significantly impacted the level of match, indicating differences between the more expert and novice participants in the role wine sweetness, acidity, and tannin had on level of match.     

不同粉碎条件对葡萄籽超微粉破壁率的影响

以赤霞珠葡萄籽为原料,研究不同的冷冻温度和粉碎时间对葡萄籽超微粉细胞破壁率的影响。借鉴理想破碎模型单元破碎率计算法,测定葡萄籽的细胞直径以及葡萄籽超微粉的粒径,并统计粒径的分布概率研究破壁率。结果表明:同一冷冻温度下,除个别条件下存在例外,葡萄籽细胞破壁率随着粉碎时间的延长有明显的升高趋势,且在-15和-25℃时破壁率与粉碎时间具有线性关系;在同一粉碎时间下,随着温度的降低破壁率有升高的趋势但不呈线性,在粉碎时间延长至75min时破壁率已达到较高水平,温度对其影响微弱。超微粉粒径小于葡萄籽细胞平均直径时,破壁率为100%;超微粉粒径大于葡萄籽细胞平均直径时,破壁率随着粒径的增大而减小。推荐较好的葡萄籽超微粉破碎条件为:冷冻温度-15℃、粉碎时间75min。     

不同粉碎条件对葡萄籽超微粉破壁率的影响

以赤霞珠葡萄籽为原料,研究不同的冷冻温度和粉碎时间对葡萄籽超微粉细胞破壁率的影响。借鉴理想破碎模型单元破碎率计算法,测定葡萄籽的细胞直径以及葡萄籽超微粉的粒径,并统计粒径的分布概率研究破壁率。结果表明:同一冷冻温度下,除个别条件下存在例外,葡萄籽细胞破壁率随着粉碎时间的延长有明显的升高趋势,且在-15和-25℃时破壁率与粉碎时间具有线性关系;在同一粉碎时间下,随着温度的降低破壁率有升高的趋势但不呈线性,在粉碎时间延长至75min时破壁率已达到较高水平,温度对其影响微弱。超微粉粒径小于葡萄籽细胞平均直径时,破壁率为100%;超微粉粒径大于葡萄籽细胞平均直径时,破壁率随着粒径的增大而减小。推荐较好的葡萄籽超微粉破碎条件为:冷冻温度-15℃、粉碎时间75min。      

Effect of grape seed oil supplementation on plasma lipid profiles in rats

The purpose of the study was to investigate the comparative effects of feeding of grape seed oil (GSO), soybean oil (SO), and lard on plasma lipid profile in rats. Lard fed diets increased body weight gain in rats and resulted in negative effects on lipoprotein metabolism. However, the GSO fed rats had a significant reduction in total cholesterol (TC, 60.6 mg/dL), low density lipoprotein cholesterol (LDLC, 16.8 mg/dL), and atherogenic index (AI, 0.9), and the ratio of high density lipoprotein cholesterol (HDLC) to TC (0.5) was significantly higher than those of SO and lard groups. These data suggest that GSO supplementation has significant health benefits through favorable alterations in plasma lipid profiles compared to SO and lard fed rats. GSO may be good dietary oil and may provide health benefits in hyperlipidemia and related complications.     

葡萄籽提取物对发酵猪肉香肠氧化稳定性的影响

以感官品质、酸价、过氧化值和硫代巴比妥酸值为指标,研究葡萄籽提取物对发酵猪肉香肠氧化稳定性的影响。实验结果表明,随着葡萄籽提取物添加量的增加,发酵猪肉香肠的感官品质变化不大,而酸价、过氧化值和硫代巴比妥酸值的变化越来越慢,表明葡萄籽提取物能明显减缓发酵猪肉香肠的产酸速度和氧化速度,进而提高其氧化稳定性;添加0.25%葡萄籽提取物对提高发酵猪肉香肠氧化稳定性效果最佳。     

葡萄籽的开发与利用

葡萄籽含有14%～17%的油脂,还含有3.9%的原花青素.为了合理利用葡萄籽资源,采用仁壳分离的方法,仁用于提取葡萄籽油,壳用于提取原花青素.同时,还对葡萄籽的国内外研究利用情况,市场应用情况和前景作了客观的分析论述,以期促进葡萄籽资源的合理利用.