Changes in Free Amino Acid and Total Nitrogen Concentrations During Maturation of Muscadine Grapes (V. rotundifolia)

Free amino acids, ammonia and total nitrogen were followed during maturation of berries of Carlos and Noble muscadine grapes (V. rotundifolia). Chemical analysis was done on deseeded berries. Ammonia decreased in the berries of both cultivars during maturation. Total nitrogen content fluctuated and was not significantly correlated with maturity in either cultivar. Threonine (THR) and histidine + gamma aminobutyric acid (HIS + GABA) were the predominant free amino acids in both cultivars at an immature berry stage. At full berry maturity, arginine (ARG) was the predominant amino acid in Carlos, having increased over 100-fold during the sampling period while ARG, alanine (ALA), THR, and HIS + GABA accounted for 72.3% of the total free amino acids. ALA was the predominant free amino acid in mature berries of Noble and accounted for 30.4% of the total free amino acids. Of the additional cultivars sampled only at their normal harvest date, berries of Pride, Magnolia and Regale contained nearly equal amounts of ARG and ALA as the predominant amino acids. Mature Dixie berries had twice as much ALA (29.8%) as ARG (12.8%). In general, the free amino acids in berries of muscadine grapes were found in concentrations similar to those reported in the literature for V. vinifera and V. labrusca cultivars. However, the large increase in proline concentration reported to occur during maturation of berries of V. vinifera cultivars was not found in any of the muscadine cultivars examined.     

Volatiles of grape berries evaluated at the germplasm level by headspace-SPME with GC–MS

Volatile aroma compounds are one of the important characteristics determining fruit quality. Evaluation of volatiles at the germplasm level is useful for future breeding efforts, aimed at improvement of fruit quality, via effects on fruit aroma. The composition and concentration of volatiles in berries of forty-two grape cultivars belonging to seven genotypic groups were evaluated by headspace solid-phase microextraction with GC–MS. Sixty volatiles were detected, of which C₆ compounds were the dominant volatiles in V. amurensis grape, neutral cultivars V. vinifera grapes and hybrid grapes between V. vinifera with V. thunbergii or V. amurensis. Alcohols and carbonyls were relatively low in all Vitis germplasm studied. Terpenoids were abundant in V. vinifera with muscat aroma, while esters were dominant in V. labrusca and its hybrids with V. vinifera or V. amurensis. Via principal component analysis, all the grape germplasm studied could be divided into three groups: (1) V. labrusca and its hybrids with V. vinifera or V. amurensis, (2) V. vinifera with muscat aroma and (3) the others, including V. vinifera without muscat aroma plus V. amurensis, and hybrids between V. vinifera and V. thunbergii or V. amurensis. Seasonal quantitative variations of volatiles were observed, but the qualitative volatile composition of the cultivars was consistent.     

Anthocyanin composition and content in grape berry skin in Vitis germplasm

The composition and content of anthocyanins were surveyed by HPLC–MS for assessing genotypic variation in berry skin of 110 grape cultivars, including 3 species and 5 interspecific hybrids. Twenty-nine anthocyanins were identified. For total anthocyanin content, Vitis vinifera and hybrids of Vitis labrusca and V. vinifera were low, and in general, wild species and rootstock were higher than interspecific hybrids, and wine grapes were higher than table grapes in the same species. As regards the composition of anthocyanins, malvidin-derivatives were the most abundant anthocyanins in the majority of germplasms. All anthocyanins were monoglucoside derivatives in V. vinifera, but all the other Vitis germplasms had both mono- and di-glucoside derivatives. Moreover, peonidin-derivatives and malvidin 3-O-glucoside were, respectively, main anthocyanins in table and wine grapes of V. vinifera. Via principal component analysis, the distribution of the cultivars in a scatter plot depended upon their total anthocyanins content, mono- and di-glucoside derivatives.     

The use of malolactic Oenococcus oeni (ATCC 39401) for deacidification of media containing glucose, malic acid and citric acid

 Malolactic fermentation is widely used to reduce the acidity of grape juices in wine production. However, application of the same technology to the production of wine from berries of the northern regions is not straightforward. Unlike grapes, these berries are rich in citric and malic acid while the sugar content is low. An ideal deacidification process for the northern berries would be the microbial degradation of these acids with minimal loss of sugars. Therefore, the co-metabolism of citric acid and glucose was studied under different conditions of malic acid degradation by Oenococcus oeni. At low pH values (pH <4.5) degradation of malic acid always proceeded first to completion with practically no consumption of glucose or citric acid. After the exhaustion of malic acid the degradation of both citric acid and glucose were initiated simultaneously. Following the exhaustion of malic acid and citric acid the remaining glucose remained nonfermentable. Thus, it is concluded that, by maintaining the culture in a resting state by the control of pH, selective degradation of acids can be achieved without subsequent loss of glucose. Received: 20 January 2000     

Polyphenolic profiles detected in the ripe berries of Vitis vinifera germplasm

Polyphenolic profiles in the berry samples of 344 European grape (Vitis vinifera) cultivars were evaluated for two consecutive years. These cultivars represent a diverse collection of V. vinifera germplasm maintained at the USDA-Agricultural Research Service Vitis Clonal Repository in Davis of California, USA. A total of 36 polyphenolic compounds, including 16 anthocyanins, 6 flavonols, 6 flavanols, 6 hydroxycinnamic acids and 2 hydroxybenzoic acids, were identified via HPLC–MS and quantified by HPLC–DAD. The mean contents for anthocyanins, flavanols, flavonols, hydroxycinnamic acids and hydroxybenzoic acids were 0.946 (coloured cultivars), 0.147, 0.043, 0.195 and 0.016 mg g⁻¹ FW, respectively. On average, wine grapes had higher concentrations than had table grapes for all of these compounds except hydroxycinnamic acids. Berry colours affected the total contents of anthocyanins, but not others. Positive correlations (0.151–0.535) were found among these groups of compounds. As expected, these groups of compounds were all negatively correlated with berry weight.     

Mass-spectrometry evidence confirming the presence of pelargonidin-3-O-glucoside in the berry skins of Cabernet Sauvignon and Pinot Noir (Vitis vinifera L.)

Background and Aims: Anthocyanins are a group of important phenolic compounds which are responsible for the colour of red grape and wine. This study aimed to confirm the existence of pelargonidin-3-O-glucoside in Vitis vinifera grape berry skins. Methods and Results: The anthocyanin profiles in the berry skins of Cabernet Sauvignon and Pinot Noir were analysed by high performance liquid chromatography – electronic spray ionization – tandem mass spectrometry. Besides 17 anthocyanins that are commonly determined in the berries of these two varieties, pelargonidin-3-O-glucoside was also detected at trace levels. Conclusions: The mass-spectrometry evidence confirmed the existence of pelargonidin-3-O-glucoside in non-teinturier V. vinifera grapes. Significance of the Study: This finding will be beneficial for the further understanding of anthocyanin profile and its biosynthesis in grape berries.     

中国野生葡萄果实基本品质、酚类物质含量及其抗氧化活性分析

中国野生葡萄资源丰富,但对其利用有限;为揭示不同种野生葡萄的品质差异及进一步利用奠定理论基础,本研究对中国野生葡萄的10个种(46个株系)和不同对照品种(4份材料)的基本品质、酚类物质含量及其抗氧化活性指标进行评价。结果表明:1)除刺葡萄外,中国野生葡萄的单果质量小于‘赤霞珠’;中国野生葡萄的皮果比高于‘赤霞珠’。2)中国野生葡萄和对照之间糖的组成相似,果糖与葡萄糖所占的比例没有差异,总糖含量显著低于‘赤霞珠’和‘户太8号’;除刺葡萄外,中国野生葡萄的总酸含量显著高于对照‘赤霞珠’和‘户太8号’,中国野生葡萄的酒石酸/苹果酸的比值低于‘赤霞珠’,说明中国野生葡萄属于高苹果酸型;河岸葡萄和圆叶葡萄的糖酸含量与中国野生葡萄的糖酸含量较接近;‘赤霞珠’和‘户太8号’属于高糖低酸型,中国野生葡萄属于低糖高酸型。3)中国野生葡萄的抗氧化活性和酚类物质的含量变异较大,大部分的野生葡萄与‘赤霞珠’的酚类物质含量和抗氧化活相近,但中国野生葡萄的花色苷含量高于对照的花色苷含量。综上所述,中国野生葡萄中的燕山葡萄、蘡薁葡萄和刺葡萄的品质较好,其与‘赤霞珠’和‘户太8号’的糖酸组分、酚类物质含量及抗氧化活性接近。     

The Proteins of Muscadine Grapes

The concentrations, molecular weights and isoelectric points of proteins present in muscadine grape cultivars were determined. The total protein contents of these grapes, are consistent with values reported in literature for V. vinifera grape proteins. Molecular weights of most of the protein fractions were, however, relatively high when compared with those of other grape cultivars. Isoelectric’ points of muscadine proteins ranged between pH 5.6 and pH 7.6.     

Pectin-derived oligosaccharides increase color and anthocyanin content in Flame Seedless grapes

BACKGROUND: Grapes grown in warm weather do not develop a desirable red color and require the use of products to enhance berry color. Pectin‐derived oligosaccharides (PDOs) have been shown to have a role in various responses including plant defense, growth and development. In this work a mixture of PDOs with 3–20 degrees of polymerization was applied to Vitis vinifera cv. Flame Seedless grapes under field conditions and compared to the effects of ethephon (an ethylene‐releasing compound). The effect of treatments on grape color, anthocyanin content and phenylalanine ammonia lyase (PAL) mRNA levels was evaluated. RESULTS: PDOs treatment increased berry color measured by the Color Index of Red Grapes (CIRG) and anthocyanin content, compared to ethephon and untreated berries (control); 1.5, 1 and 0.5 mg mL^?1 PDOs increased berry color by 30%, 27% and 26%, respectively, when compared to control berries. Levels of PAL mRNA accumulating in berries treated with PDOs were elevated within the first 24 h of treatment. CONCLUSIONS: PDOs enhanced the color and anthocyanin content of Flame Seedless grape berries possibly due by the induction of PAL mRNA expression. The results demonstrated that PDOs can be used to improve fruit quality aspects such as berry skin color. Copyright © 2011 Society of Chemical Industry     

Changes in Concentration of Certain Elements During Maturation of Muscadine Grapes (Vitis rotundifolia)

Changes in percent ash and certain elements were followed during maturation of berries of two cultivars of muscadine grapes (Vitis rotundifolia). Analyses were done on deseeded berries. Percent ash increased significantly during maturation of Carlos berries, but did not increase significantly during maturation of Noble berries. Potassium was the element in highest concentration in both cultivars during maturation and at harvest. Potassium, calcium, phosphorus, and sodium were the major elements found to be significantly correlated with maturation and were found in concentrations similar to those reported in the literature for V. vinifera grapes. Iron, copper, zinc, and manganese were minor components. Four additional muscadine cultivars, sampled only at full maturity, had similar concentrations of elements to those found in ripe berries of Carlos and Noble. The averaged values of ash (%) and elements (ppm) for all six cultivars when sampled at their normal harvest dates are: ash = 0.57; Na = 58.6 (Carlos and Noble only); P = 99.6; K = 1641.0; Ca = 124.2; Mg = 59.2; Mn = 7.2; Cu = 0.5; Zn = 0.5; Fe = 3.0.     

Phenolic compounds and fatty acids in different parts of Vitis labrusca and V. vinifera grapes

trans-Resveratrol, antioxidant activity, phenolic compounds, proximate composition, and fatty-acid composition were quantified in different parts (peel, pulp, and seeds) of four grape varieties: Brazil (Vitis vinifera), Benitaka (V. vinifera), Isabel (Vitis labrusca) and Niagara (V. labrusca). Large concentrations of polyunsaturated fatty acid (18.84 and 9204.27 mg 100 g^− 1), linoleic acid (LA, 18:2n-6), from 5890.87 to 9148.93 mg 100 g^− 1, and alpha-linolenic (LNA, 18:3n-3), from 5.25 to 56.85 mg 100 g^− 1, were found in different parts of the four grape varieties. The lowest concentrations necessary for 50% inhibition of DPPH were (9.26 to 126.91 ??g mL^− 1) in seeds; the pulp did not have antioxidant activity. The total phenolic content varied between 0.04 and 122.35 mg EAG g^− 1; seeds had the highest concentrations (89.83 to 122.35 mg EAG g^− 1), especially in Niagara and Isabel varieties. trans-Resveratrol was detected in peels (1.17 to 12.96 ??g g^− 1) and seeds (2.03 to 2.44 ??g g^− 1) of the four varieties; however, it was absent in the pulp.     

Changes in the glucose: Fructose ratio during the growth period of the razaki grape

The fructose content of table grapes is of importance, especially for cultivars growing in cold climates. The glucose: fructose ratio (G: F ratio) in the table grape Vitis vinifera L, cv. Razaki during the entire growth period was determined by polarimetric and volumetric methods, This ratio was found to be 1.95 at the beginning of the growth period and 1.55 in the final stage of growth (over-ripe), with an excess of glucose throughout. The G:F ratio decreased until the middle of August and was almost constant thereafter, Acidity decreased until mid-September, when the berries reached maximum weight.     

BIOCHEMISTRY OF UNEVEN RIPENING IN GULABI GRAPE1

Physico-chemical changes, organic acids content and activities of enzymes related to softening, glycolytic, gluconeogenic and organic acids metabolism were studied from 70 to 100 days after anthesis in ripening of berries of Gulabi grape. Uneven ripening was observed in 70 day old clusters. The disorder affected 22.76 and 32.38% of berries in bunches harvested at 90 and 100 days, respectively. Unripe berries had less dry matter, sugars, skin anthocyanins and more seed, fresh weight and acidity compared to ripe berries. Green berries had more malic and less tartaric acid, while brown berries had less malic acid and black berries contained more tartaric acid. Green berries contained more polygalacturonase, cellulase, hexokinase, glucose 6-phosphatase, phosphoenol pyruvate carboxylase, pyruvate decarboxylase and polyphenol oxidase activities than ripe fruit. Brown berries contained the highest phosphofractokinase, malate and glutamate dehydrogenase activities, and black berries had the highest activities of pectinesterase, fructose 1,6-bisphosphatase and malic enzyme. The role of dry matter, malic acid, pectinesterase and certain enzymes of gluconeogenic and organic acids metabolism in uneven ripening is discussed.     

First steps towards the development of a non-destructive technique for the quality control of wine grapes during on-vine ripening and on arrival at the winery

NIR spectroscopy was used as a non-destructive technique for the assessment of changes in certain internal quality properties of wine grapes (Vitis vinifera L.) during on-vine ripening and at harvest. A total of 108 different wine grape samples were used to construct calibration models based on reference data and NIR spectral data, obtained using a commercially-available diode-array spectrophotometer (380-1700 nm). The feasibility of testing bunches of intact grapes was investigated and compared with more traditional methods of presentation, such as berries or must. Predictive models were constructed to quantify changes in soluble solid content (SSC, °Brix), reducing-sugar content (g/l), pH-value, titrable acidity (g/l tartaric acid), tartaric acid (g/l) and malic acid (g/l), these being the major parameters used to chart ripening. NIRS technology provided good precision for the bunch analysis mode assayed for SSC (r² = 0.89; SECV = 1.41 °Brix), for reducing-sugar content (r² = 0.87; SECV = 17.13 g/l) and for pH-value (r² = 0.69; SECV = 0.19). Models developed for testing other fruit acidity parameters yielded results sufficient to provide a screening tool to distinguish between low and high acidity values in intact grapes. Significantly, the results obtained with bunch presentation were similar to those obtained with berries and must, thus justifying further implementation of NIRS technology for the non-destructive analysis of quality properties both during on-vine ripening and on arrival at the winery. This method allows musts to be processed separately depending on initial grape quality, assessed with a single spectrum measurement and in a matter of seconds.     

Sugars, sugar alcohols, fruit acids, and ascorbic acid in wild Chinese sea buckthorn (Hippophaë rhamnoides ssp. sinensis) with special reference to influence of latitude and altitude

Wild berries of Hippophaë rhamnoides ssp. sinensis were collected from nine natural growth sites in China in three consecutive years in order to get an overall profile of the sugars, sugar alcohols, fruit acids, and ascorbic acid, and especially of the influence of the latitude and altitude of the growth place on these components. The contents of fructose, glucose, and l-quebrachitol in the berry juice varied in the ranges of 0.01-7.17, 0.05-7.85 and 0.21-1.09 g/100 mL, respectively, those of malic, quinic, and ascorbic acids were 1.55-8.84, 0.07-2.94, and 0.25-1.66 g/100 mL, respectively. The berries from Hebei and Inner Mongolia were characterized by high contents of sugars and l-quebrachitol and low contents of malic acid and ascorbic acid. In contrast, the berries from Sichuan and Qinghai contained lower contents of sugars and higher contents of malic acid and ascorbic acid than the berries from other growth areas. The berries from Sichuan differed considerably from others by the remarkably low contents of sugars and the exceptionally high contents of acids. The contents of fructose, glucose, and total sugar decreased as the altitude increased and as the latitude decreased (p < 0.05). In contrast, the contents of malic acid and ascorbic acid increased as the altitude increased and as the latitude decreased (p < 0.05). The contents of quinic acid and l-quebrachitol correlated strongly and positively with the latitude (p < 0.01).     

Phenolic profile of Sercial and Tinta Negra Vitis vinifera L. grape skins by HPLC–DAD–ESI-MS: Novel phenolic compounds in Vitis vinifera L. grape

This study represents the first phytochemical research of phenolic components of Sercial and Tinta Negra Vitis vinifera L. The phenolic profiles of Sercial and Tinta Negra V. vinifera L. grape skins (white and red varieties, respectively) were established using high performance liquid chromatography–diode array detection–electrospray ionisation tandem mass spectrometry (HPLC–DAD–ESI-MSⁿ), at different ripening stages (véraison and maturity). A total of 40 phenolic compounds were identified, which included 3 hydroxybenzoic acids, 8 hydroxycinnamic acids, 4 flavanols, 5 flavanones, 8 flavonols, 4 stilbenes, and 8 anthocyanins. For the white variety, in both ripening stages, hydroxycinnamic acids and flavonols were the main phenolic classes, representing about 80% of the phenolic composition. For red variety, at véraison, hydroxycinnamic acids and flavonols were also the predominant classes (71%), but at maturity, anthocyanins represented 84% of the phenolic composition. As far as we know, 10 compounds were reported for the first time in V. vinifera L. grapes, namely protocatechuic acid-glucoside, p-hydroxybenzoyl glucoside, caftaric acid vanilloyl pentoside, p-coumaric acid-erythroside, naringenin hexose derivate, eriodictyol-glucoside, taxifolin-pentoside, quercetin-glucuronide-glucoside, malylated kaempferol-glucoside, and resveratrol dimer. These novel V. vinifera L. grape components were identified based on their MSⁿ fragmentation profile. This data represents valuable information that may be useful to oenological management and to valorise these varieties as sources of bioactive compounds.     

Effect of maturation and cold storage on the organic acid composition of myrtle fruits

BACKGROUND: The effect of maturation and senescence on the chemical composition of two myrtle cultivars was studied in mature, overripe and cold‐stored fruits in order to find the most appropriate harvesting period and best storage technology for industrial purposes. RESULTS: After cold storage at 10 °C for 15 days, berry weight loss ranged from 12.5 to 18.4%, with the highest losses in less mature fruits. Titratable acidity decreased during maturation and cold storage in both cultivars. Reducing and total sugars increased during maturation. Anthocyanin concentration increased during maturation but decreased in overripe berries. The major organic acids in myrtle fruits were quinic, malic and gluconic acids. In fresh and cold‐stored fruits, malic acid rose to 3 g kg^?1 and decreased thereafter. Quinic acid peaked at 90 or 120 days after bloom and decreased thereafter to reach low concentrations in mature fruits. CONCLUSION: Cold storage for 15 days at 10 °C does not affect myrtle fruit quality for liqueur production. Anthocyanin concentration is the best indicator of harvest time for industrial purposes. Gluconic acid concentration is high in mature, overripe and cold‐stored berries. This parameter can be used as a marker of the onset of fruit senescence. Copyright © 2012 Society of Chemical Industry     

Sugars and Acid Analysis and Effect of Heating on Color Stability of Northwest Concord Grape Juice

Changes during storage in color of Concord grape juice extracted after heating to different temperatures and the carbohydrate and nonvolatile acid composition of Concord grapes were studied. Heating crushed Concord grapes under pilot plant conditions to 88° and 99°C inactivated nearly all of the polyphenoloxidase, increased the extraction of anthocyanins (ACN) and reduced polymeric color in the grape juice. During storage of the juice for 8 months, the rate of ACN degradation and color density decrease was the same in all samples. Glucose, fructose and sucrose were the only sugars found in Northwest Concord grapes, while malic and tartaric acids were the major nonvolatile acids. Lesser amounts of phosphoric, citric and coumaric acids were present.     

Polyphenolic composition and content in the ripe berries of wild Vitis species

To explore wild genetic resources for improving fruit and processing quality of cultivated grape cultivars, the polyphenolic composition and content in the ripe berries of 147 grape accessions from 16 Vitis species for two consecutive years were characterised. A total of 48 polyphenolic compounds, including 28 anthocyanins, 6 flavonols, 6 flavanols, 6 hydroxycinnamic derivatives, and 2 hydroxybenzoic acids, were identified via HPLC-MS and quantified by HPLC-DAD. These wild grape species had unique presence of abundant di-glucoside derivatives of anthocyanins. In addition, anthocyanins in most wild species were predominantly nonacylated. The mean contents for anthocyanins, flavanols, flavonols, hydroxycinnamic derivatives, and hydroxybenzoic acids were 9.610, 0.769, 0.093, 0.441 and 0.027 mg g⁻¹ FW, respectively. They were about 2 to 10 folds higher than their respective counterparts in the most widely cultivated grape species Vitis vinifera. As expected, most of these groups of compounds were correlated negatively with berry weight, but positively with the content of total soluble solids.