Influence of grapevine leafroll associated viruses (GLRaV-2 and -3) on the fruit composition of Oregon Vitis vinifera L. cv. Pinot noir: Free amino acids,sugars, and organic acids

Individual free amino acids, yeast assimilable amino acid (YAN) content, ammonia, organic acids, and simple sugars of berries from vines infected with GLRaV-2 or -3 were compared with paired vines free of these viruses. Samples were taken from two commercial vineyards during two growing seasons (2005 and 2006), with three different rootstock/scion combinations. Vines infected with GLRaV-2 did not differ significantly from their healthy counterparts in individual free amino acids, ammonia, or YAN content. Vines infected with GLRaV-3 were significantly lower in valine and methionine from Vitis riparia rootstock/‘Pinot noir’ clone 114 (VY2a) samples, and lower in glutamic acid from self-rooted/‘Pinot noir’ clone Pommard (VY2b) samples, compared to samples from their healthy counterparts. Samples from VY2b (self-rooted/‘Pinot noir’ clone Pommard) infected vines had significantly lower levels of malic acid and total organic acids compared to samples from their healthy counterparts. There were no significant differences between healthy and infected vines from all three rootstock/scion pairs in ammonia or free amino acids in samples taken during the weeks before ripening and at commercial harvest. This is the first study to report the influence of GLRaV-2 and -3 on ‘Pinot noir’ berries nitrogen (N) compounds significant to fermentation. Individual free amino acids may be inferior to phenolic compounds as indicators of GLRaV infection status.     

Profiles of free amino acids in grapes of grafted Chardonnay grapevines

Chardonnay grapes from a rootstock trial in the Murray Valley region of South Australia were sampled for two seasons and concentrations of free amino acids in grape extract ('juice') were determined. The lowest concentrations of free assimilable amino-N were measured in Chardonnay grapes from vines on 140 Ruggeri and 101–14 rootstocks, and the highest concentrations were in grapes from vines on their own roots, Schwarzmann and K51–40. Free assimilable amino-N concentrations were sufficient to sustain fermentation through to completion. Arginine concentrations were generally too low to expect significant concentrations of urea in the wine. Amino-S concentrations were much lower and varied less than amino-N concentrations. The effect of any particular rootstock on the concentration of total free amino acids in Chardonnay grape 'juice' did not appear to be related to the known effects of those rootstocks on the NO₃-N status of petioles at flowering. The concentrations of leucine, iso-leucine, valine, threonine, tyrosine and phenylalanine were generally higher in Chardonnay grapes grafted onto K51–40 in comparison to grapes from Chardonnay vines grafted on the other rootstocks. Any of these amino acids may be associated with the presence of specific higher alcohols in wine.     

Rootstock effects on salt tolerance of irrigated field-grown grapevines (Vitis vinifera L. cv. Sultana). 3. Fresh fruit composition and dried grape quality

Field‐grown vines of cv. Sultana on either their own roots or grafted to a range of rootstocks, were drip‐irrigated at one of three salinity levels (0.40, 1.75 and 3.50 dS/m) over a five year period. Rootstocks were Ramsey, 1103 Paulsen, J17‐69 and 4 hybrids (designated R1, R2, R3 and R4) derived from parentage involving Vitis champini, V. berlandieri and V. vinifera. Grape juice total soluble solids, titratable acidity and pH were measured at harvest, while colour of dried fruit was measured before and after processing and again after six months storage. Damage index (an indicator of skin damage) was measured post‐processing; sugar crystal formation in dried grapes and dried grape compaction were measured post‐storage. There was a strong salinity x rootstock interaction for grape juice soluble solids concentration, soluble solids yield (the product of soluble solids concentration and fruit yield) and pH, but not for titratable acidity when analysed on the basis of 5 year means. Small increases (< 5%) in juice soluble solids concentration were recorded at medium salinity (1.75 dS/m) for the low vigour genotypes, Sultana on own‐roots and on J17‐69 rootstock, based on the 5 year means and Fisher's protected (interaction) LSDs. Moderate increases (< 10%) also occurred in years of low crop load e.g. 1993 at high salinity for the high vigour rootstock R2 and in 1995 at medium salinity for Sultana on own roots and at high salinity for Sultana on R1 rootstock. By contrast, decreases in soluble solids concentration occurred with increasing salinity for the high vigour rootstocks (Ramsey, 1103 Paulsen and R2) in years of high crop load e.g. 1992. Small (< 2%) increases in grape juice pH were recorded at high salinity for Sultana on R3 rootstock and moderate increases (< 7%) in grape juice titratable acidity were recorded at high salinity for Sultana on own roots and Sultana on J17‐69, R1, R2 and R4 rootstocks. Dried grapes from all treatments achieved a light amber colour (quality grade termed 5 crown light) and were generally of high quality. Sultanas from own‐rooted grapevines were redder (higher ‘a‐value’) than sultanas from 1103 Paulsen and Ramsey when assessed as unprocessed fruit, after processing (both years) and after 6 weeks storage. While soluble solids yields per vine were 23–31% lower at high salinity for Sultana on own roots and on R1, R3 and R4 rootstocks, they were unaffected by high salinity for Ramsey, 1103 Paulsen and R2 rootstocks. Moreover, soluble solids yields for Sultana on Ramsey, 1103 Paulsen and R2 rootstocks were 1.4 to 2.5‐fold higher than for Sultana on the other rootstocks at high salinity. This study has shown that over a 5 year period rootstocks such as Ramsey, 1103 Paulsen and R2 grafted with Sultana were tolerant of salinity, producing dried grapes of generally high quality.     

不同砧木对阳光玫瑰白兰地品质的影响

以自根、贝达、3309C、5BB为砧木,以阳光玫瑰葡萄为原料酿造白兰地,研究四种砧木阳光玫瑰葡萄发酵过程中的理化指标、有机酸及香气成分的影响,探讨不同砧木对阳光玫瑰白兰地品质的影响。结果表明,随着发酵时间的延长,糖分含量呈先下降后保持稳定的趋势,酒精度呈先上升后保持稳定的趋势,自根砧木阳光玫瑰葡萄发酵液中残糖含量最高,为7.8%,3309C、贝达、5BB阳光玫瑰葡萄发酵液中残糖含量均为7.0%。自根、贝达、3309C、5BB砧木葡萄果实有机酸总量分别为1.45 g/100 mL、1.09 g/100 mL、1.05 g/100 mL、0.99 g/100 mL。自根、贝达、3309C、5BB砧木葡萄发酵及蒸馏过程中共分别检出18种、26种、24种、10种香气成分,其中主要包括醇类、酸类、酯类及醛类。综合评价,贝达砧木较其他砧木的阳光玫瑰白兰地品质好。     

Free amino acid profiles from ‘Pinot noir’ grapes are influenced by vine N-status and sample preparation method

This study examined the impact of extraction method on ammonia, free amino acids, and yeast assimilable nitrogen (YAN) concentrations in ‘Pinot noir’ berries obtained from a vine nutrition study (altered supply of N, P, or K). Berries were either juiced or exhaustively extracted as whole berries prior to analysis. Extracts, compared to juice samples, had a significantly higher level of ammonia–N, assimilable amino acid–N, and YAN. For example, juice YAN values were approximately 50% of extract YAN values, when both were expressed in the same units. Free amino acid profiles and relative concentrations of individual amino acids were different in juice versus extracts, depending on how well the skin fraction was extracted prior to analysis. Lowering N supply reduced free amino acids, with arginine being reduced more than the other 20 free amino acids identified in ‘Pinot noir’ berries. This was true in both juice and extracts. Since berry skin contributed to actual YAN, wineries that determine YAN from mainly the pulp fraction (juice) may underestimate YAN and as a result add more (artificial) N supplement than is required for the healthy fermentation of red winemaking (whole berry fermentations). Extraction procedure should be taken into consideration when comparing grape YAN.     

Quality analysis of ‘Redhaven’ peach fruit grafted on 11 rootstocks of different genetic origin in a replant soil

The fruit quality of ‘Redhaven’ peach [Prunus persica (L.) Basch.] grafted on 11 (Adesoto, Julior, GF 677, Monegro, Barrier 1, Cadaman, MrS 2/5, Ishtara, Penta, Tetra and peach seedling) experimental rootstocks was evaluated in 2008 under replant orchard conditions. Several quality indices [weight, flesh firmness (FF), ground colour measurements, and soluble solids content (SSC)] were measured, and HPLC analysis were performed for numerous chemical parameters (quantification of individual sugars, organic acids, phenolic compounds in skin and in pulp). Total phenolic content and antioxidant capacity in skin and in pulp were also measured. Julior had the heaviest fruit, while Barrier 1 and GF 677 produced fruit lighter in weight. Rootstocks influenced harvest maturity. Monegro produced the least ripe fruit, characterised by high FF, phenolic compounds in the skin and low SSC. Adesoto rootstock resulted in the best overall fruit quality (high values of SSC, individual and total sugar content levels, individual and total organic acids and phenolic compounds in pulp) as well as high total yield. Julior rootstock also produced good quality peach (high values of SSC, individual and total sugars). Cadaman and peach seedling rootstock produced ‘Redhaven’ fruit of the lowest quality, indicated by low values of sugars, organic acids, phenolic compounds in pulp and in skin.     

Effects of timing and rate of N supply on leaf nitrogen status, grape yield and juice composition from Shiraz grapevines grafted to one of three different rootstocks

Yeast cells have a minimum N requirement to ferment a must through to dryness, so that grape N content (hence must N) becomes critical in meeting that prerequisite. Viticultural practices aimed at meeting that N requirement are of special relevance because interactions between rootstock and vineyard nitrogen supply strongly influence scion mineral nutrient status as well as shoot vigour, and via those processes, fruit composition. Such outcomes were investigated in a field trial involving Shiraz on three rootstocks viz. Teleki 5C, Schwarzmann and Ramsey. Five N supply regimes, varying from 0 to 80 kg/(haseason), were imposed through a drip-irrigation system during two periods (either flowering to veraison, or post-harvest to leaf-fall, or both) over three successive growing seasons. Post-harvest N supply increased scion leaf N and nitrate N concentrations at flowering for vines on Teleki 5C and Schwarzmann. By veraison, N recently applied in the flowering to veraison period elevated these indicators of N status in all vines on all rootstocks. Grape yields from vines on Teleki 5C and Schwarzmann were elevated by N supply after harvest, whereas juice soluble solids levels were lowered. Free amino acids in Shiraz juice were dominated by non-assimilable N, amounting to about 50% or more of the total free amino-N in the juice. Increasing N supply increased free amino acid concentrations in the juice of berries from vines on all rootstocks, but only vines on Schwarzmann derived any benefit from N supplied after harvest. The highest concentrations of free amino acids were measured in the berries from vines on Schwarzmann receiving 80 kg N/(ha.season). Of immediate practical relevance for N management of Shiraz grapevines on either Teleki 5C or Ramsey rootstocks, the minimum value for assimilable free amino-N concentration required to ferment a must through to dryness was not achieved if vineyard N application was limited to the post-harvest period.     

Implications of nitrogen nutrition for grapes, fermentation and wine

This review discusses the impacts of nitrogen addition in the vineyard and winery, and establishes the effects that nitrogen has on grape berry and wine composition and the sensory attributes of wine. Nitrogen is the most abundant soil‐derived macronutrient in a grapevine, and plays a major role in many of the biological functions and processes of both grapevine and fermentative microorganisms. Manipulation of grapevine nitrogen nutrition has the potential to influence quality components in the grape and, ultimately, the wine. In addition, fermentation kinetics and formation of flavour‐active metabolites are also affected by the nitrogen status of the must, which can be further manipulated by addition of nitrogen in the winery. The only consistent effect of nitrogen application in the vineyard on grape berry quality components is an increase in the concentration of the major nitrogenous compounds, such as total nitrogen, total amino acids, arginine, proline and ammonium, and consequently yeast‐assimilable nitrogen (YAN). Both the form and amount of YAN have significant implications for wine quality. Low must YAN leads to low yeast populations and poor fermentation vigour, increased risk of sluggish/stuck/slow fermentations, increased production of undesirable thiols (e.g. hydrogen sulfide) and higher alcohols, and low production of esters and long chain volatile fatty acids. High must YAN leads to increased biomass and higher maximum heat output due to greater fermentation vigour, and increased formation of ethyl acetate, acetic acid and volatile acidity. Increased concentrations of haze‐causing proteins, urea and ethyl carbamate and biogenic amines are also associated with high YAN musts. The risk of microbial instability, potential taint from Botrytis‐infected fruit and possibly atypical ageing character is also increased. Intermediate must YAN favours the best balance between desirable and undesirable chemical and sensory wine attributes. ‘Macro tuning’, of berry nitrogen status can be achieved in the vineyard, given genetic constraints, but the final ‘micro tuning’ can be more readily achieved in the winery by the use of nitrogen supplements, such as diammonium phosphate (DAP) and the choice of fermentation conditions. This point highlights the need to monitor nitrogen not only in the vineyard but also in the must immediately before fermentation, so that appropriate additions can be made when required. Overall, optimisation of vineyard and fermentation nitrogen can contribute to quality factors in wine and hence affect its value. However, a better understanding of the effect of nitrogen on grape secondary metabolites and different types of nitrogen sources on yeast flavour metabolism and wine sensory properties is still required.     

Fungicide effects on ammonium and amino acids of Monastrell grapes

The influence of six fungicides (famoxadone, fenhexamid, fluquinconazole, kresoxim-methyl, quinoxyfen and trifloxystrobin) on the amino acids and ammonium composition of grapes (var. Monastrell) are studied. The treatments were performed under critical agricultural practices (CAP), 6 h before grape collection. The analytical determination of amino acids and ammonium were made using HPLC with a photodiode array detector (DAD), after derivatisation of the sample with diethyl (ethoxymethylene)malonate (DEEMM). The application of fungicides to the vine decreased concentrations of nitrogenous compounds in grapes. Furthermore, the qualitative and quantitative effects on the amino acids in the grapes depended on the type of fungicide used. The fungicides which affected the highest number of amino acids were famoxadone and fenhexamid, while quinoxyfen affected the lowest number of amino acids. Grapes treated with famoxadone contained the lowest concentration of total amino acids.     

Developmental changes of carbohydrates,organic acids,amino acids,and phenolic compounds in ‘Honeycrisp’ apple flesh

The developmental changes of carbohydrates, organic acids, amino acids and phenolic compounds in ‘Honeycrisp’ apple flesh were investigated using GC–MS and HPLC. A total of 12 carbohydrates, 8 organic acids, 20 amino acids, and 18 phenolic compounds were identified and quantified. Each metabolite showed characteristic changes during fruit development, but in general, concentrations of most sugars and sugar alcohols either increased or remained unchanged whereas concentrations of most organic acids, amino acids and phenolic compounds decreased with fruit development, indicating that most sugars and sugar alcohols are synthesised and/or accumulate at a faster or similar rate relative to fruit growth whereas organic acids, amino acids and phenolics are synthesised and/or accumulate at a slower rate relative to fruit growth. On a whole fruit basis, the content of most metabolites increased with fruit development. In the flesh of mature ‘Honeycrisp’ apple, fructose and sucrose and sorbitol are the major sugars and sugar alcohol; malic acid is the major organic acid; aspartic acid, asparagine, glutamic acid, proline, threonine and γ-aminobutyric acid are the major amino acids; and procyanidin B1, procyanidin B2, chlorogenic acid, catechin and epicatechin are the major phenolic compounds, respectively.     

Sugar and acid concentrations in 98 grape cultivars analyzed by principal component analysis

A total of 98 grape cultivars were studied for content and composition of organic acids and sugars in grape juice during two consecutive years. Glucose and fructose were the predominant sugars in grape berries and ranged from 45.86 to 122.89 mg mL^?1, and 47.64 to 131.04 mg mL^?1, respectively, in two years. Sucrose was present at trace amounts in most cultivars, but two cultivars of hybrids between Vitis labrusca and V. vinifera contained large amounts of sucrose. Tartaric acid content in berries, varying from 1.57 to 9.09 and 1.54 to 9.05 mg mL^?1, respectively, in two years, was significantly higher than malic acid, which ranged from 0.38 to 6.05 and 0.36 to 7.06 mg mL^?1, respectively, in two years. Moreover, significantly higher total soluble sugars and fructose and lower total acids and malic acid were found in cultivars from hybrids between V. labrusca and V. vinifera than those in V. vinifera cultivars, and wine grapes had higher total sugars and acids than table grapes from V. vinifera. Principal component analysis (PCA) indicated that genotypic correlations among sugar and acid contents were stable and the first three PCs accounted for about 82% of total variance in both years. PC1 was highly connected with glucose and fructose contents, and sucrose was an important contributor to the variance for PC2, as well as for PC3. PC2 and PC3 were highly connected also with organic acids, but the contributor to variance differed from one year to the next. Tartaric acid was the main contributor to variance in 2003, and malic acid was important in 2004 for PC2 and PC3. In a scatter plot of the score values of all genotypes projected to the PC1 and PC2 plane, three groups of cultivars tend to cluster based on their genetic background or purpose of use. The cultivars of hybrid V. labrusca and V. vinifera were represented by high sugars, especially sucrose, and low acids. Among the cultivars of V. vinifera, wine grapes were found in general to have more sugars and acids than table grapes. The composition of sugars was stable in grape berries between the two years, while acids were sensitive to climate changes. Finally, the different responses of malic and tartaric acids to climate change is discussed. Copyright © 2006 Society of Chemical Industry     

Yeast and bacterial modulation of wine aroma and flavour

Wine is a highly complex mixture of compounds which largely define its appearance, aroma, flavour and mouth‐feel properties. The compounds responsible for those attributes have been derived in turn from three major sources, viz. grapes, microbes and, when used, wood (most commonly, oak). The grape‐derived compounds provide varietal distinction in addition to giving wine its basic structure. Thus, the floral monoterpenes largely define Muscat‐related wines and the fruity volatile thiols define Sauvignon‐related wines; the grape acids and tannins, together with alcohol, contribute the palate and mouth‐feel properties. Yeast fermentation of sugars not only produces ethanol and carbon dioxide but a range of minor but sensorially important volatile metabolites which gives wine its vinous character. These volatile metabolites, which comprise esters, higher alcohols, carbonyls, volatile fatty acids and sulfur compounds, are derived from sugar and amino acid metabolism. The malolactic fermentation, when needed, not only provides deacidification, but can enhance the flavour profile. The aroma and flavour profile of wine is the result of an almost infinite number of variations in production, whether in the vineyard or the winery. In addition to the obvious, such as the grapes selected, the winemaker employs a variety of techniques and tools to produce wines with specific flavour profiles. One of these tools is the choice of microorganism to conduct fermentation. During alcoholic fermentation, the wine yeast Saccharomyces cerevisiae brings forth the major changes between grape must and wine: modifying aroma, flavour, mouth‐feel, colour and chemical complexity. The wine bacterium Oenococcus oeni adds its contribution to wines that undergo malolactic fermentation. Thus flavour‐active yeasts and bacterial strains can produce desirable sensory results by helping to extract compounds from the solids in grape must, by modifying grape‐derived molecules and by producing flavour‐active metabolites. This article reviews some of the most important flavour compounds found in wine, and their microbiological origin.     

Rootstock effects on salt tolerance of irrigated field-grown grapevines (Vitis vinifera L. cv. Sultana) 2. Ion concentrations in leaves and juice

Field vines of cv. Sultana, grown either on their own roots, or grafted to a range of rootstocks, were drip‐irrigated at three salinity levels (0.40, 1.75 and 3.50 dS/m) over a five‐year period. Rootstocks comprised Ramsey, 1103 Paulsen, J17‐69 and 4 hybrids (designated R1, R2, R3 and R4) derived from parentage involving Vitis champini, V. berlandieri and V. vinifera. Concentrations of Cl^‐, Na+, K+, Ca²⁺ and Mg²⁺ were measured in petioles at flowering, and in laminae and grape juice at harvest, in each year of the trial. Vines on all rootstocks accumulated less chloride in either petioles at flowering or in laminae and juice at harvest compared with vines on own roots at all salinity treatments. By inference, all rootstocks behaved as chloride excluders relative to the roots of own‐rooted vines. 1103 Paulsen was the best chloride excluder based on lowest concentrations of accumulated Cl^‐ in petioles, laminae and grape juice at high salinity. Sultana on R3 rootstock at high salinity accumulated more Na+ in both laminae and grape juice (at harvest) than did Sultana on own roots or on any of the other rootstocks. Laminae K+ at harvest time was reduced at high salinity in Sultana on own roots and on all rootstocks. Concentrations of both Cl^‐ and Na+ in petioles at flowering and in laminae and grape juice at harvest showed no significant correlation with either yield (as kg of fresh grapes per vine) or vigour (as measured by fresh weight of one‐year‐old pruning wood per vine) for any salinity treatment. There was however, a strong positive correlation between yield and the subsequent weight of one‐year‐old pruning wood for all salinity treatments. There was also a negative correlation between Na+ concentrations in petioles at flowering and the subsequent weight of one year‐old‐pruning wood from the 0.40 dS/m treatment. Similar negative correlations were found between Na+ concentration in both laminae and grape juice at harvest time, and the subsequent weight of one‐year‐old pruning wood from the 0.40 dS/m treatment (but not from either the 1.75 or 3.50 dS/m treatments). Based on these findings and those from Walker et al. 2002a we conclude that a high innate vigour of a rootstock combined with moderate to high chloride and sodium exclusion ability represents the best combination for salt tolerance in Sultana grapevines as measured by yield at moderate to high salinity.     

Biofortification with selenium and lithium improves nutraceutical properties of major winery grapes in the Midwestern United States

Enriching the micronutrients, selenium (Se) and lithium (Li), in grapes to improve their nutraceutical properties were implemented by foliar application of organic fertiliser rich in Se and Li onto five grape cultivars. The effects of this biofortification on vine vigour, fruit quality, overall micronutrients and phenolic compounds also were investigated. Agronomic biofortification was found greatly increased the Se and Li content in the whole grape by multiple times, meanwhile it did not significantly affect the vine vigour and fruit quality of grapes. However, the biofortification did impact the Ionome (including all the mineral nutrients and trace elements) and phenolic compounds in grapes and this varied among cultivars. This study demonstrated foliar spray of organic Se/Li fertiliser was a very effective strategy to biofortify these micronutrients in grape berries, particularly in the skin, and therefore might be a promising strategy to increase the consumption and awareness of these grapes.     

Effects of solar ultraviolet radiation and canopy manipulation on the biochemical composition of Sauvignon Blanc grapes

Background and Aims: New Zealand is exposed to relatively high solar ultraviolet (UV) radiation; such high irradiances of UV radiation having the potential to change the biochemical composition of plants. The aim of this study was to investigate the effects of UV radiation and the role of canopy leaves on berry biochemical composition in Vitis vinifera var. Sauvignon Blanc. Sauvignon Blanc is the major grape variety grown in New Zealand. Methods and Results: Leaves were removed from around the fruiting zones of vines and screens that altered UV radiation exposures were placed over the grape bunches. Samples taken throughout development were analysed for changes in total phenolic compounds (including flavonols), amino acids and methoxypyrazines. Total phenolic compounds increased substantially in response to UV‐B exposure and this was reflected in changes taking place within the skins of the berries. Flavonol levels were determined by UV‐B radiation exposure and accumulated to maximum concentrations at veraison, subsequently declining to harvest. UV radiation did not have a significant effect on the majority of amino acids or methoxypyrazine concentrations. The most noticeable change in amino acid and methoxypyrazine accumulation was caused by the presence of leaves over the fruiting zone, retaining these leaves maintained significantly higher concentrations in the berries at harvest. Conclusions: UV‐B radiation determines the composition of flavonols in the skins of grapes. Amino acid and methoxypyrazine concentrations are not predominantly determined by UV‐B, but retention of leaves over the fruiting zone promotes their accumulation in berries. Significance: Canopy manipulations are routinely used commercially in the vineyard to help control vigour and reduce disease pressure. The findings presented here are important for viticulturists to understand how management of the vine leaf canopy can determine the biochemical composition of the grapes and can therefore, ultimately affect wine quality.     

欧亚种‘丹娜’葡萄不同砧穗组合果实香气物质的差异比较

利用气相色谱-质谱联用技术，连续两年（2016和2017年）研究了‘1103P’、‘140R’、‘101-14’、‘3309C’、‘SO4’和‘贝达’6 种砧木嫁接对‘丹娜’（Vitis vinifera L. cv. ‘Tannat’）葡萄果实香气物质积累的影响。结果表明：2016年，不同砧木对果实香气影响更加显著，其中‘1103P’可以显著提高‘丹娜’葡萄果实C6/C9类物质的总含量，游离态的己醇、(Z)-3-己烯醇、(E)-2-己烯醛和正己醛是其特征性的C6/C9化合物；‘140R’有利于‘丹娜’葡萄果实酯类物质的合成；而‘3309C’则降低了‘丹娜’葡萄果实酯类、C6/C9类和挥发性酚类香气物质的含量。‘贝达’和‘SO4’在两个年份中均提高了‘丹娜’葡萄果实萜烯类物质的含量；‘SO4’还可以显著提高‘丹娜’葡萄果实C13-降异戊二烯类物质的含量，其特征性C13-降异戊二烯类化合物为游离态(E)-β-大马士酮和(Z)-β-大马士酮。本研究可以为实际生产中‘丹娜’葡萄嫁接砧木的选择与应用提供一定的参考。     

Volatile compounds formation in alcoholic fermentation from grapes collected at 2 maturation stages: influence of nitrogen compounds and grape variety

The aim of this work was to study the influence of nitrogen compounds on the formation of volatile compounds during the alcoholic fermentation carried out with 4 nonaromatic grape varieties collected at 2 different maturation stages. To do this, Monastrell, Merlot, Syrah, and Petit Verdot grapes were collected 1 wk before harvest and at harvest. Then, the musts were inoculated with the same Saccharomyces cerevisiae yeast strain and were fermented in the same winemaking conditions. Amino acids that showed the highest and the lowest concentration in the must were the same, regardless of the grape variety and maturation stage. Moreover, the consumption of amino acids during the fermentation increased with their concentration in the must. The formation of volatile compounds was not nitrogen composition dependent. However, the concentration of amino acids in the must from grapes collected 1 wk before harvest can be used as a parameter to estimate the concentration of esters in wines from grapes collected at harvest and therefore to have more information to know the grape oenological capacity. Application of principal components analysis (PCA) confirmed the possibility to estimate the concentration of esters in the wines with the concentration of nitrogen compounds in the must.     

An assessment of rootstocks for Sunmuscat (Vitis vinifera L.): a new drying variety

Sunmuscat scions, either grafted onto one of seven rootstock, or as own-rooted vines, were grown under irrigation according to the practices of warm-climate viticulture in north-western Victoria. The trial was located within a commercial vineyard on a sandy loam soil, and represented a typical replant situation. Grapevine performance was assessed over five seasons, viz. 1999–2004 inclusive, in terms of yield per vine, berry weight, juice composition and vigour (based on trunk girth). The highest yielding rootstock over the trial period was 1103 Paulsen (28.9 kg /vine) followed by 140 Ruggeri and Ramsey (26.1 and 25.8 kg /vine respectively), S04 (22.5 kg /vine), Schwarzmann, 101-14 and Teleki 5A (19.9, 18.7 and 18.4 kg /vine respectively). Scions on their own roots returned lowest yield (15.5 kg /vine). Berry weights were largest for the three high yielding rootstocks (2.3 g) and smallest with own roots (2.0 g). Total soluble sugars in harvested fruit were largely unaffected by rootstock in most seasons, although taken over all seasons, fruit from scions grafted onto Ramsey rootstock had the lowest levels, while Teleki 5A had the highest levels (viz. 23.4^oBrix and 24.7^oBrix respectively). Comparative vigour for all seven graft combinations was inferred from trunk circumference. There was a 2-fold difference in rootstock girth below the graft union (viz. 265 mm for 1103 Paulsen, compared to 135 mm for S04), whereas differences in the scion girth above the graft union were minor (only 16%). Relative compatibility of scion and stock was inferred from 'girth ratio' of trunk circumference above compared with below the graft union. Girth ratio was highest for Sunmuscat scions grafted onto SO4 rootstock, and lowest for scions on 1103 Paulsen. Scion girth and vine yield were broadly correlated.     

Interaction of rootstock and applied water amounts at various fractions of estimated evapotranspiration (ETc) on productivity of Cabernet Sauvignon

Background and Aims: It is commonly thought that grapevine rootstocks vary in their tolerance to drought. This study examined the interaction between various applied water amounts and productivity of Cabernet Sauvignon grafted onto five rootstocks. Methods and Results: The commercial vineyard used in this study was located along the central coast of California. The rootstocks used were Teleki 5C, 110 Ricter, 140 Ruggeri, 1103 Paulson and Freedom. Irrigation amounts ranged from 0.25 up to 1.25 of estimated vineyard evapotranspiration. Midday leaf water potential (Ψ_l), was significantly affected by irrigation treatment but not by rootstock. There was a significant effect of irrigation treatment and rootstock on berry weight, number of bunches per vine and yield but no interaction between those two factors. The rootstock 5C had the lowest yield compared with the other rootstocks. Yield at the 0.25 irrigation level was approximately 62% of the yield at the 1.25 irrigation level across rootstocks. Irrigation treatment was the only factor that significantly affected soluble solids in the fruit. There was a significant interaction between rootstock and irrigation amount on pruning weights. Berry weight, yield and pruning weights were linearly correlated with midday Ψ_l across rootstock and year. Conclusions: The results indicate that the rootstocks producing greater yields at the highest applied water amounts also produced greater yields when deficit irrigated. Significance of the Study: Under both stressed and non-stressed conditions, the rootstocks with the highest yield were those with the greatest number of bunches.     

Influence of jam processing upon the contents of phenolics,organic acids and free amino acids in quince fruit (<Emphasis Type="Italic">Cydonia oblonga</Emphasis> Miller)

Phenolic compounds, organic acids and free amino acids of quince were evaluated, before and after jam processing, to test the effect of thermal processing in these compounds. In addition, the composition of jams prepared with peeled and unpeeled quinces was compared. Phenolics, organic acids and free amino acids were analysed by HPLC/DAD, HPLC/UV and GC/FID, respectively.