Glycosidic aroma compounds of some Portuguese grape cultivars

In order to evaluate the potential aroma of some Portuguese grapes, several glycosidically bound aroma compounds of ten grape varieties grown in Évora, Alentejo, Portugal, were released, identified and quantified using gas chromatography–mass spectrophotometry. White varieties were Arinto, Perrum, Rabo‐de‐Ovelha, Roupeiro and Antão Vaz. Red varieties were Trincadeira, Aragonez, Tinta Caiada, Moreto and Castelão. Grapes of Roupeiro and Trincadeira from five other vines in the Alentejo region were also studied. For each variety pulp and skin were analyzed separately. The compounds produced by enzymatic hydrolysis of glycoside precursors extracted from pulps and skins of these grapes were similar to the ones appearing in the so‐called ‘aromatic’ varieties; however, the amounts found were significantly lower. These results seem to show the neutral characteristic of these grapes to indicate that each variety has a distinctive profile regarding compounds from the linalool class. The ratios of trans : cis forms of some linalool compounds remain the same in all samples of Roupeiro and Trincadeira, regardless their origin. In Trincadeira grapes no linalool was detected. Skins are always richer than pulps. The acid hydrolysis of norisoprenoid aglycons produced highly odorant compounds previously described in grape varieties. Although some differences between varieties could be detected, the red grapes Aragonez and Castelão are richer in vitispiranes while Moreto, Trincadeira and Tinta Caiada are richer in actinidols; in white grapes, only Roupeiro and Perrum show detectable amounts of vitispiranes. These results need further investigation and analysis to be considered as a statement and should be confirmed in an extended study. Copyright © 2006 Society of Chemical Industry     

Influence of grape composition and winemaking on the anthocyanin composition of red wines of Tannat

The anthocyanin composition of Tannat red wines obtained with four winemaking techniques was evaluated in different years. The wines were elaborated with traditional maceration (TM), cold pre‐fermentative maceration, delayed extraction of anthocyanins and extended maceration. Two vinifications were carried out for each technique, employing 70 kg of grapes in each one. The anthocyanin composition of wines was analysed by high‐performance liquid chromatography–diode array detection. The results confirm the fundamental role of the grape composition on the anthocyanin composition of the wines. The winemaking had an important effect on the total concentration of anthocyanins and also may modify the anthocyanic profile of wines. The wines obtained with TM had higher or similar content of anthocyanins than those elaborated with the other techniques. Canonical discriminant analysis of data showed that vintage has a greater effect on anthocyanin concentration than winemaking techniques.     

刺葡萄汁与其它几种葡萄汁及葡萄酒的原花青素含量对比

采用铁盐催化比色法,对刺葡萄汁、巨峰葡萄汁以及几种商品葡萄汁和2种葡萄酒中的原花青素含量进行了对比测定。结果表明:刺葡萄汁中的原花青素含量为3147μg/mL,巨峰葡萄汁为1187μg/mL,Welch’s紫葡萄汁2476μg/mL,蒙娜丽莎干红葡萄酒2854μg/mL,长城干红葡萄酒2757μg/mL,可见刺葡萄汁中原花青素含量显著高于其它葡萄汁和葡萄酒中的含量。     

连续流动-水杨酸盐分光光度法测定葡萄酒及 葡萄汁中氨氮含量

目的利用连续流动分析仪建立以水杨酸-次氯酸盐比色法为基础的葡萄酒和葡萄汁中氨氮的分析方法。方法葡萄汁及葡萄酒样品经过滤后直接进样,试样与试剂在蠕动泵的推动下进入化学反应模块,在密闭的管路中连续流动,并按特定的顺序和比例混合、反应,显色完全后进入流动检测池进行光度检测。结果氨氮标准溶液利用12%乙醇溶液配制线性范围为0~60 mg/L,相关系数(r2)大于0.999;方法检出限(LOD)为0.015mg/L。在低、中、高三个浓度水平添加下,样品氨氮回收率范围为90.0%~96.8%,相对标准偏差(n=6)均小于1%。结论该方法灵敏度高,重复性好,操作简便,适用于大批量葡萄酒和葡萄汁中氨氮含量的检测。     

超临界二氧化碳萃取山葡萄籽油的研究

对超临界CO2萃取山葡萄籽油的工艺条件进行了研究,研究了原料粉碎粒度、萃取压力、萃取温度和萃取时间对葡萄籽出油率的影响。结果表明:原料粉碎粒度60目,萃取压力30Mpa,萃取温度35℃,萃取时间160min为最佳工艺条件,在此条件下,出油率可达18.31%。     

Characterisation of Bobal and Crujidera grape cultivars,in comparison with Tempranillo and Cabernet Sauvignon: Evolution of leaf macronutrients and berry composition during grape ripening

We present characterisation data for two Spanish autochthonous grapevines, Bobal and Crujidera, in comparison with the well-known cultivars Tempranillo and Cabernet Sauvignon. Microsatellite markers were used for the molecular characterisation of Crujidera grapevines. Leaf macronutrient contents of the four cultivars were evaluated, as well as their changes at different vine developmental stages, and veraison was seen as the most suitable time to evaluate the nutritional status. Quantitative changes in some physiological parameters and the phenolic composition of the four grape varieties were measured during the last month of ripening. Polyphenols, tannins and anthocyanins increased with grape maturation, although the accumulation of these phenolic compounds and their patterns of evolution varied considerably with the cultivar. The biosynthetic potential of these grapes to produce resveratrol largely depended on the grape variety, with a remarkably high content found in Bobal berry skins.     

Antioxidant and antimicrobial potentials of Serbian red wines produced from international Vitis vinifera grape varieties

BACKGROUND: Antioxidant and antimicrobial potentials of Serbian red wines produced from different international Vitis vinifera grape varieties and their correlation with contents of phenolic compounds were studied by spectrophotometric and chromatographic methods. The antioxidant activity of red wines was estimated through their ability to scavenge 2,2′‐diphenyl‐1‐picrylhydrazyl free radical (DPPH^?). The red wines, gallic acid, (+)‐catechin and quercetin were screened in vitro for antimicrobial activity against Gram‐positive and Gram‐negative strains using microdilution and disc diffusion techniques. RESULTS: Excellent correlations between the contents of quercetin‐3‐glucoside (R² = 0.9463) and quercetin (R² = 0.9337) and DPPH^?‐scavenging ability of the red wines were found. Serbian red wines exhibited significant activity against Staphylococcus aureus, Listeria inocua, Micrococcus flavus, Sarcina lutea, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Shigella sonnei strains, which was in correlation with their phenolic composition and antioxidant activity. The compounds gallic acid, quercetin and (+)‐catechin showed high activity against B. subtilis, S. aureus, S. lutea and M. flavus Gram‐positive and S. enteritidis and P. aeruginosa Gram‐negative strains. CONCLUSION: The results show that quercetin‐3‐glucoside and quercetin concentrations can be used as markers for the determination of antioxidant and antimicrobial potentials of red wines. Copyright © 2012 Society of Chemical Industry     

Physicochemical characteristics and functional properties of grape (Vitis vinifera L.) seeds protein

The amino acid composition, physicochemical and functional properties of grape (Vitis vinifera L.) seeds protein (GSP) were evaluated and compared with those of soybean protein isolate (SPI). Amino acid analyses of GSP revealed high levels of glutamic/glutamine, glycine and aspartic/asparagines. SDS‐PAGE analysis demonstrated that globulin was the major protein component in GSP, whose subunit molecular weights were mainly varied from 25.5 to 40.0 kDa. The isoelectric pH of GSP was found to be at the acidic pH of around 3.8. At all the pHs tested except pH 2.0, no significant changes of GSP secondary structure were observed. GSP exhibited beneficial functional properties such as preferable solubility and emulsifying activity, while the foaming properties and water holding capacity were relatively poor compared to SPI. It could then be employed to soup, sauce, beverage or meat product for improving nutritional and sensory quality of these foods at appropriate pHs.     

Uptake of grape anthocyanins into the rat kidney and the involvement of bilitranslocase

Anthocyanins are among the most common flavonoids in the human diet. In spite of their very low bioavailability, anthocyanins are indicated as active in preventing the progress of cardiovascular and neurodegenerative diseases, obesity, inflammation, and cancer. Any piece of knowledge concerning absorption, tissue distribution, metabolism, and excretion of dietary anthocyanins is expected to help understanding the apparent paradox between their low concentrations in cells and their bioactivity. The aim of this work was to investigate the renal uptake of dietary anthocyanins and the underlying molecular mechanism. A solution containing anthocyanins extracted from grape (Vitis vinifera) was introduced into the isolated stomach of anesthetized rats; after both 10 and 30 min, plasma, liver, and kidney were analyzed for their anthocyanin contents. While anthocyanins in the liver were at apparent equilibrium with plasma both after 10 and 30 min, kidney anthocyanins were 3- and 2.3-fold higher than in plasma, after 10 and 30 min, respectively. Since the transport activity of the bilitranslocase in kidney basolateral membrane vesicles was competitively inhibited by malvidin 3-glucoside (K(i) = 4.8 +/- 0.2 microM), the anthocyanin uptake from blood into kidney tubular cells is likely to be mediated by the kidney isoform of this organic anion membrane transporter.     

Physiological responses and quality attributes of table grape fruit to chitosan preharvest spray and postharvest coating during storage

The effects of preharvest chitosan spray (PCS) or/and postharvest chitosan coating (PCC) treatments on the quality and physiological response of table grape fruit stored at 20 or 0 °C was evaluated, respectively. PCS/PCC treatment showed the best control effect on decay. PCC or PCS/PCC treatment significantly decreased the weight loss of fruit stored at 20 °C. Additionally, all chitosan treatments inhibited the increase in rate of soluble solid content to titratable acid in fruit, stored at 20 °C, while enhancing the rate at 0 °C and affecting the content of total phenolic compounds in the fruit. Furthermore, the activities of superoxide dismutase decreased in all chitosan treatments and PCS or/and PCC treatments also changed the activities of polyphenol oxidase, peroxidase and phenylalanine ammonia-lyase. The results indicated the beneficial effect of chitosan by preharvest spray and/or postharvest coating on fruit quality and resistance to fruit decay.     

Chemical composition of dietary fiber and polyphenols of five different varieties of wine grape pomace skins

The skins of two white wine grape pomace (WWGP) and three red wine grape pomace (RWGP) from US Pacific Northwest were analyzed for their dietary fiber (DF) and phenolic composition. DF was measured by gravimetric–enzymatic method with sugar profiling by HPLC–ELSD. Insoluble DF composed of Klason lignin (7.9–36.1% DM), neutral sugars (4.9–14.6% DM), and uronic acid (3.6–8.5% DM) weighed more than 95.5% of total DF in all five WGP varieties. WWGP was significantly lower in DF (17.3–28.0% DM) than those of RWGP (51.1–56.3%), but extremely higher in soluble sugar (55.8–77.5% DM vs. 1.3–1.7% DM) (p < 0.05). Soluble polyphenols were extracted by acidified 70% acetone and measured spectrophotometrically. Compared with WWGP, RWGP had higher values in total phenolic content (21.4–26.7 mg GAE/g DM vs. 11.6–15.8 mg GAE/g DM) and DPPH radical scavenging activity (32.2–40.2 mg AAE/g DM vs. 20.5–25.6 mg AAE/g DM) (p < 0.05). The total flavanol and proanthocyanidin contents were ranged from 31.0 to 61.2 mg CE/g DM and 8.0 to 24.1 mg/g DM, respectively for the five WGP varieties. This study demonstrated that the skins of WGP can be ideal sources of DF rich in bioactive compounds.     

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。      

基于ANN和PCA的玉米品种特征分析与识别研究

研究了一种基于玉米外观形态和颜色特征进行的玉米品种的特征主分量分析及BP神经网络识别方法。采用数码相机获得了11个品种每个品种50粒共550幅图像,然后对各品种对应的籽粒群体图像提取每个籽粒的形态特征8个,颜色特征12个、纹理特征13个,共33个特征参数,采用主分量分析PCA的方法提取其主分量,将这些主分量作为BP神经网络的输入,构建4层神经网络,并分别定义11个玉米品种的二进制编码作为网络的输出,建立特征参数与玉米品种之间的神经网络识别模型。试验结果表明,方法对11个品种550个籽粒的品种检出率为92%以上,得到了较好的识别效果。