Acids In Berries Research Articles

Extraction and Determination of Phenolic Compounds in the Berries of Sorbus americana Marsh and Lonicera oblongifolia (Goldie) Hook

Phenolic compound content in Sorbus americana Marsh and Lonicera oblongifolia (Goldie) Hook berries was determined for the first time. An improved solid-liquid microextraction (SLME) method combining with high-performance liquid chromatography (HPLC)-diode array detector (DAD)-mass spectrometry (MS) has been developed to determine the phenolic compounds present in these berries, reducing the amount of sample, reagents, and time consumed. The major phenolic compound identified and quantified was 3-O-caffeoylquinic acid (3-CQA) in both berries. To a lesser extent, 5-O-caffeoylquinic acid (5-CQA) and quercetin-3-O-glucoside (QG) were also determined. The existence of these phenolic compounds and the great abundance of these fruits in the northeast of North America make S. americana Marsh and L. oblongifolia Hook berries a new and excellent source of natural phenolic compounds (antioxidants), which can be very useful in biotechnological exploitation.

Manipulating the leaf area to fruit mass ratio alters the synchrony of total soluble solids accumulation and titratable acidity of grape berries

Background and Aims This study investigated: (i) the importance of changing the leaf area: fruit mass ratio (LA : FM) by crop removal and/or shoot trimming on total soluble solids (TSS) concentration and content, pH, titratable acidity (TA) and berry mass; (ii) the extent to which changes in LA : FM ratio altered the synchrony TSS : TA ratio; and (iii) whether the responses were consistent for Pinot Noir and Sauvignon Blanc. Methods and Results Vertical shoot positioned–trained vines were trimmed shortly after fruitset or at veraison to six or 12 main leaves per shoot and crop thinned by removing 0, 50 or 75% of the bunches. TSS and pH, TA and fresh berry mass were measured weekly from pre-veraison to harvest. TSS concentration accumulation in berries was slowed with shoot trimming and accelerated by crop removal, with crop removal having a greater effect. Trimming shoots at fruitset in combination with no crop removal resulted in the greatest delay in veraison (the start of TSS accumulation) and slowest rate of TSS accumulation. TSS content mirrored TSS concentration for LA : FM manipulations at fruitset but fewer differences were detected for LA : FM changes at veraison. In contrast, TA and pH were largely unaffected. Conclusions Changes to the LA : FM ratio via crop removal or shoot trimming modified berry TSS accumulation but not TA. Such desynchronisation was consistent for both cultivars. Significance of the Study Crop and/or leaf removal represent valuable means to manipulate the time to achieve target fruit TSS concentration and TA. The similar responses of the two cultivars indicate that LA : FM manipulation could potentially have common responses for different cultivars. The desynchronisation of berry components highlights the need to consider each berry component individually and in a dynamic manner by sampling throughout the ripening phase.

Construction of a high-density genetic map and QTLs mapping for sugars and acids in grape berries.

BackgroundQTLs controlling individual sugars and acids (fructose, glucose, malic acid and tartaric acid) in grape berries have not yet been identified. The present study aimed to construct a high-density, high-quality genetic map of a winemaking grape cross with a complex parentage (V. vinifera × V. amurensis) × ((V. labrusca × V. riparia) × V. vinifera), using next-generation restriction site-associated DNA sequencing, and then to identify loci related to phenotypic variability over three years.ResultsIn total, 1 826 SNP-based markers were developed. Of these, 621 markers were assembled into 19 linkage groups (LGs) for the maternal map, 696 for the paternal map, and 1 254 for the integrated map. Markers showed good linear agreement on most chromosomes between our genetic maps and the previously published V. vinifera reference sequence. However marker order was different in some chromosome regions, indicating both conservation and variation within the genome. Despite the identification of a range of QTLs controlling the traits of interest, these QTLs explained a relatively small percentage of the observed phenotypic variance. Although they exhibited a large degree of instability from year to year, QTLs were identified for all traits but tartaric acid and titratable acidity in the three years of the study; however only the QTLs for malic acid and β ratio (tartaric acid-to-malic acid ratio) were stable in two years. QTLs related to sugars were located within ten LGs (01, 02, 03, 04, 07, 09, 11, 14, 17, 18), and those related to acids within three LGs (06, 13, 18). Overlapping QTLs in LG14 were observed for fructose, glucose and total sugar. Malic acid, total acid and β ratio each had several QTLs in LG18, and malic acid also had a QTL in LG06. A set of 10 genes underlying these QTLs may be involved in determining the malic acid content of berries.ConclusionThe genetic map constructed in this study is potentially a high-density, high-quality map, which could be used for QTL detection, genome comparison, and sequence assembly. It may also serve to broaden our understanding of the grape genome.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0428-2) contains supplementary material, which is available to authorized users.

Ultraviolet-B radiation modifies the quantitative and qualitative profile of flavonoids and amino acids in grape berries

Grapevine cv. Tempranillo fruit-bearing cuttings were exposed to supplemental ultraviolet-B (UV-B) radiation under controlled conditions, in order to study its effect on grape traits, ripening, amino acids and flavonoid profile. The plants were exposed to two doses of UV-B biologically effective (5.98 and 9.66kJm−2d−1), applied either from fruit set to ripeness or from the onset of veraison to ripeness. A 0kJm−2d−1 treatment was included as a control. UV-B did not significantly modify grape berry size, but increased the relative mass of berry skin. Time to reach ripeness was not affected by UV-B, which may explain the lack of changes in technological maturity. The concentration of must extractable anthocyanins, colour density and skin flavonols were enhanced by UV-B, especially in plants exposed from fruit set. The quantitative and qualitative profile of grape skin flavonols were modified by UV-B radiation. Monosubstituted flavonols relative abundance increased proportionally to the accumulated UV-B doses. Furthermore, trisubstituted forms, which where predominant in non-exposed berries, were less abundant as UV-B exposure increased. Although total free amino acid content remained unaffected by the treatments, the increased levels of gamma-aminobutyric acid (GABA), as well as the decrease in threonine, isoleucine, methionine, serine and glycine, revealed a potential influence of UV-B on the GABA-mediated signalling and amino acid metabolism. UV-B had an overall positive impact on grape berry composition.

Effects of Vine Water Status on Dimethyl Sulfur Potential, Ammonium, and Amino Acid Contents in Grenache Noir Grapes (Vitis vinifera)

We studied the effect of vine water status on the dimethyl sulfur potential (DMSP), ammonium, and amino acid contents of the berry during the maturation of Grenache Noir grapes. Water deficit increased the accumulation of amino acids in berries and favored yeast assimilable amino nitrogen. Similarly, ammonium content was higher in berries from vines subjected to moderate water deficit. DMSP content followed the same trend as yeast assimilable amino acid content, with higher concentrations observed in the berries of vines subjected to water deficit. The high DMSP and yeast assimilable nitrogen contents of musts from vines subjected to water deficit resulted in a better preservation of DMSP during winemaking. The wines produced from these musts had a higher DMSP level and would therefore probably have a higher aroma shelf life, because the DMSP determines the rate of release of dimethyl sulfur during wine storage, and this compound enhances fruity notes.

Elevated root-zone temperature hastens vegetative and reproductive development in Shiraz grapevines

Background and Aims Springtime root-zone warming activates mobilisation of the root carbohydrate reserves, a critical source of carbon for early canopy and reproductive development in grapevines following winter dormancy. Seasonal variability in soil temperature during spring may result in inconsistent vegetative growth and fruitset with consequences for berry growth and ripening. Methods and Results We monitored flowering and berry ripening in Shiraz grapevines (Vitis vinifera L.) grown in large temperature-controlled pots. The vines were exposed to a cool, ambient and warm root-zone temperature from budburst to fruitset. Root starch mobilisation after budburst was linearly correlated to the cumulative heat units received by the soil. A warm root-zone temperature also hastened leaf expansion, net positive carbon assimilation, onset of flowering and fruit set, berry enlargement and the onset of veraison. At harvest, berry pH and nitrogen concentration as well as fresh and dry mass were higher for the vines exposed to a warm root-zone while berry acidity was lower. Conclusions Warm soil temperature in spring stimulated the mobilisation of carbohydrates in the roots and accelerated shoot and reproductive development, resulting in larger berries with lower acidity. Significance of the Study Because root-zone temperature is an environmental driver of berry size and composition, models predicting yield and berry composition can be fine-tuned to incorporate this critical parameter.

Analysis of Acidic Endogenous Phytohormones in Grapes by Using Online Solid-Phase Extraction Coupled with LC-MS/MS

Phytohormones play important roles in regulating numerous plant physiological and developmental processes, even during the postharvest storage period. In order to determine the functions and changes of gibberellins acid (GA3), indoleacetic acid (IAA), abscisic acid (ABA), indolebutyric acid (IBA) and jasmonic acid (JA) in grape berries during storage, an ultrasensitive method based on direct injection online solid-phase extraction coupled with high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed. Grape berries were extracted with cold methanol. After centrifugation, the supernatants were concentrated with a vacuum centrifugal concentrator and injected into an online solid-phase extraction column. After the cleanup procedure, the analytes were determined by LC-MS/MS. The results showed that the linearity of the proposed method was 10-210 µg kg(-1) for ABA, 20-200 µg kg(-1) for IBA, 15-320 µg kg(-1) for IAA, 20-320 µg kg(-1) for GA3 and 3.0-90.0 µg kg(-1) for JA. The limits of detection of the method were 0.71, 2.79, 0.94, 0.39 and 0.57 µg kg(-1), respectively. The proposed method was successfully applied to the analysis of endogenous phytohormones in grape berries during the postharvest storage period.

N, P, and K Supply to Pinot noir Grapevines: Impact on Berry Phenolics and Free Amino Acids

Understanding the direct role that macronutrient supply (N, P, and K) has on berry chemistry was evaluated in Pinot noir grapevines grown in sand culture. Self-rooted Pinot noir vines were grown for three years with either full nutrition (Control) or three reduced levels of either N, P, or K supply while holding all other nutrients constant. Vines were managed to minimize differences in vine water status (altering irrigation to achieve similar daily soil moisture content) and fruit cluster solar exposure (altering leaf pulling to achieve similar cluster irradiance) due to varying nutrient supply so that indirect effects on berry chemistry could be largely eliminated. Berry chemistry was evaluated in the second and third years after different nutrient supply treatments were imposed. Results showed that low N, but not low P or K, altered berry free amino acid (FAA) and phenolic profiles. Low N supply reduced FAA and yeast assimilable nitrogen (YAN) in both years by up to 70% and altered certain FAAs more than others, thus changing berry FAA profile. The concentration of sugars, anthocyanins, and flavonol-glycosides increased in low N vines during the third season, but the increase in sugars and anthocyanins was attributed to the decline in berry size that year. Condensed tannins and total phenolic acids were increased in low N vines across both years, independent of changes in berry size. Results indicated that low N supply altered YAN to the greatest degree, while anthocyanin enhancement did not occur until yield and berry size were also reduced. Increased concentrations of tannins and phenolic acids in berries occurred in response to low N supply independent of reductions in yield and berry size.

Genetic variability of descriptors for grapevine berry acidity in Riesling, Gewürztraminer and their progeny

Background and Aims The acidity of harvested grapevine berries is likely to decrease in the future because of increasing temperature during grape ripening. The aim of the study was to evaluate the genetic variability of berry acidity descriptors in progeny from a Riesling × Gewürztraminer cross. Methods and Results The ripening process for the parent cultivars was monitored over three growing seasons; berries from Riesling had a higher tartaric acid concentration than that from Gewürztraminer, and a similar difference was observed for malic acid. A statistical model describing the decline in malic acid concentration over time was fitted to the data. With this model, the parameter that best characterised the two genotypes was the asymptotic minimum value of malic acid concentration per g of berry dry matter. In addition, the rate of decrease of malic acid was constant across years when thermal-time scales were used. Using samples of green berries at veraison and samples picked 230 degree days after veraison (mean temperature, base 10°C), 120 genotypes from a Riesling × Gewürztraminer progeny were compared over 3 years in the vineyard and segregations for all the berry acidity descriptors were described. Conclusions A significant genotypic variability was observed for the concentration of malic and tartaric acids but also for the estimated cationic content of the berries for the same developmental stage. No genotypes, however, were detected, with a concentration of total malic and tartaric acid significantly higher than that of Riesling. Significance of the Study These results show that berry acidity descriptors are heritable traits that can be manipulated in breeding programs.

The vacuolar channel VvALMT9 mediates malate and tartrate accumulation in berries of Vitis vinifera

Vitis vinifera L. represents an economically important fruit species. Grape and wine flavour is made from a complex set of compounds. The acidity of berries is a major parameter in determining grape berry quality for wine making and fruit consumption. Despite the importance of malic and tartaric acid (TA) storage and transport for grape berry acidity, no vacuolar transporter for malate or tartrate has been identified so far. Some members of the aluminium-activated malate transporter (ALMT) anion channel family from Arabidopsis thaliana have been shown to be involved in mediating malate fluxes across the tonoplast. Therefore, we hypothesised that a homologue of these channels could have a similar role in V. vinifera grape berries. We identified homologues of the Arabidopsis vacuolar anion channel AtALMT9 through a TBLASTX search on the V. vinifera genome database. We cloned the closest homologue of AtALMT9 from grape berry cDNA and designated it VvALMT9. The expression profile revealed that VvALMT9 is constitutively expressed in berry mesocarp tissue and that its transcription level increases during fruit maturation. Moreover, we found that VvALMT9 is targeted to the vacuolar membrane. Using patch-clamp analysis, we could show that, besides malate, VvALMT9 mediates tartrate currents which are higher than in its Arabidopsis homologue. In summary, in the present study we provide evidence that VvALMT9 is a vacuolar malate channel expressed in grape berries. Interestingly, in V. vinifera, a tartrate-producing plant, the permeability of the channel is apparently adjusted to TA.

Fine-Tuning a Tart Grape

Plant Science![Figure][1] CREDIT: © IRENE GRASSI A good wine is a complex blend of flavors, at least some of which are based on the acidity of the wine, which is derived from the acidity of the grape. Grape berry acidity depends on potassium concentration, with high potassium content leading to less acidic fruit. As the grape berry ripens and sugars accumulate, potassium also accumulates. Potassium physiology in grape berries, however, is not well understood. Cuellar et al. have now identified in grapevine ( Vitis vinifera ) a potassium channel, encoded by the gene VvK1.2 , as well as kinase- and calcium-sensing partners that regulate the function of the channel. Accumulation of VvK1.2 transcripts, which are expressed in the berry flesh, accelerated with fruit ripening. Drought stress during the berry-ripening phase brought further increases in VvK1.2 transcript accumulation. Increased capacity for and regulation of potassium transport may be critical for successful ripening of the grape berry as it adjusts to fluctuating conditions that result from changes in internal vascular support and external drought conditions. Plant J. 73 , 1006 (2013). [1]: pending:yes

Antimicrobial activity of sloe berry purees on Salmonella spp.

The antimicrobial effects of sloe berry purees in processed and fresh form were investigated against four nalidixic acid resistant Salmonella spp. at 25 °C for 0, 15 min, 30 min, 1 h, 24 h, 48 h and at 4 °C for 30 min. The effect of pH on the antimicrobial efficacy was also determined in the neutralized fresh or processed fruit purees at 25 °C for 0 and 30 min. The results had showed that Salmonella spp. were reduced in the range of 4.33–6.55 and 4.24–6.70 logarithmic units in the processed and fresh sloe berry purees within 24 h at 25 °C, respectively. Significant differences were not obtained between processed and fresh sloe berry purees except for 30 min treatments. In this study, the effect of media also determined that there was no significant difference between Thin Agar Layer Method (TAL), Xylose Lysine Desoxycholate Agar supplemented with 50 ppm nalidixic acid (XLDN) or XLDN supplemented with 0.1% sodium pyruvate (XLDNP) for the resuscitation of injured cells. Pyruvic acid has no effect on the recovery of injured cells. Neutralized sloe berry purees showed that the acidity of sloe berry is responsible for the antimicrobial activity. At 4 °C, the antimicrobial effects of processed or fresh sloe berry purees for 30 min resulted in about 0.93–1.15 log unit and 0.63–0.66 log unit reductions, respectively. The present study indicated that sloe berry puree has antimicrobial activity on Salmonella spp. at 25 °C. Sloe berry has the potential to enhance food safety in food industry as a natural preservative.

Abstracts from Presentations at the ASEV Eastern Section 37th Annual Meeting & National Viticulture Research Conference, 16–19 July 2012, Traverse City, MIQuantitative Analysis of Phytic Acid in Grape Seeds, Stems, and Berries of Cabernet franc and Petit VerdotUnderstanding the Relationship between Fermentation-Derived Aromas and Juice Nitrogen CompositionEffect of Cold Soak and On-Skin Fermentation on the Phenolic Content of Aromatic White

# Quantitative Analysis of Phytic Acid in Grape Seeds, Stems, and Berries of Cabernet franc and Petit Verdot {#article-title-2} Phytic acid is a strong chelator and antioxidant naturally present in plant seeds. It has been shown to help prevent metal cation catalyzed oxidation and improve protein

Effects of Genotype, Latitude, and Weather Conditions on the Composition of Sugars, Sugar Alcohols, Fruit Acids, and Ascorbic Acid in Sea Buckthorn (Hippophaë rhamnoides ssp. mongolica) Berry Juice

Sea buckthorn berries (Hippophaë rhamnoides ssp. mongolica) of nine varieties were collected from three growth locations in five inconsecutive years (n = 152) to study the compositional differences of sugars, sugar alcohols, fruit acids, and ascorbic acid in berries of different genotypes. Fructose and glucose (major sugars) were highest in Chuiskaya and Vitaminaya among the varieties studied, respectively. Malic acid and quinic acid (major acids) were highest in Pertsik and Vitaminaya, respectively. Ascorbic acid was highest in Oranzhevaya and lowest in Vitaminaya. Berry samples of nine varieties collected from two growth locations in five years (n = 124) were combined to study the effects of latitude and weather conditions on the composition of H. rhamnoides ssp. mongolica. Sea buckthorn berries grown at lower latitude had higher levels of total sugar and sugar/acid ratio and a lower level of total acid and were supposed to have better sensory properties than those grown at higher latitude. Glucose, quinic acid, and ascorbic acid were hardly influenced by weather conditions. The other components showed various correlations with temperature, radiation, precipitation, and humidity variables. In addition, fructose, sucrose, and myo-inositol correlated positively with each other and showed negative correlation with malic acid on the basis of all the samples studied (n = 152).

EFFECTS OF EARLY DEFOLIATION IN GRAPE YIELD AND QUALITY IN 'MANDO', AN AUTOCHTHON CULTIVAR OF SOUTH-EAST SPAIN

In the old-world viticulture autochthonous varieties are an important inheritance because they can provide wines with authenticity and distinction. Cultivar Mando is an almost extinguished variety from the south-east of Spain with very large and tight clusters. The aim of this study was to assess the usefulness of early defoliation as a possible tool to reduce cluster compactness, improving fruit composition. With this in mind, an experiment was conducted with 'Mando' in deficit irrigated vines trained with a divided Lyre system. Control (C), non-defoliated vines, were compared with defoliation carried out either just before anthesis (phenological phase H, (Def-H)), at flowering (phenological phase I, (Def-I)) or at fruit set (phenological stage J, (Def-J)). In all the defoliation treatments, leaves from the first eight nodes, including laterals, were removed. The experimental design was a complete randomized block with three replicates per treatment and 24 experimental vines per experimental plot. As an average for all defoliation treatments, berry number per cluster, berry weight and yield were reduced by 44%, 16% and 45%,in Def-H, Def-I and Def-J respectively. Defoliation increased berry soluble solids concentration only in the Def-H treatment. On the other hand, berry acidity was only decreased in the Def-H treatment. In the ED and LD defoliation treatments, leaf pulling improved berry quality determined by a berry tasting panel. In agreement, berries from the ED and LD also had higher total phenolics, anthocyanins and tannin concentration. Results obtained were judged positively by the winery owners and defoliation, particularly at stage J, will now be more widely conducted in the vineyards planted with the 'Mando' cultivar. The research is indeed an example of a successful transfer of a research technique under commercial situations.

Optimisation of an HPLC method for the simultaneous quantification of the major sugars and organic acids in grapevine berries

A high performance liquid chromatographic method was developed to profile major sugars and organic acids in grapevine berries. Sugars and organic acids in grapevine berries were extracted by chloroform/polyvinylpolypyrrolidone purification. The extracts were chromatographed on an Aminex HPX-87H ion-exchange HPLC column with 5mM sulphuric acid as mobile phase. Chromatography was visualised via a diode array detector combined with a refractive index detector. The analysis was calibrated using external standard calibration and a novel equation was used to calculate the concentrations of malic acid and fructose from unresolved separation. For the method to be utilised for analysing a large numbers of berry samples, each sample was directly injected after sample extraction and the extraction step was downscaled to allow the use of small amounts of sample material. The concentrations of sugars and organic acids in grapevine berry samples were normalised to the internal standard concentrations obtained after extraction of an internal standard mixture. The analysis method exhibits a good precision and a high analyte recovery from samples spiked with the standard mixture and is suitable for the profiling of major sugars and organic acids in grapevine berry samples at different stages of berry development. This is the first report on the combined profiling of the major sugars and organic acids in grapevine berries using milligram amounts of plant material with direct injection after sample extraction.

Antioxidative, Antibacterial and Antifungal Activities of Tea Infusions from Berry Leaves, Carob and Doum

This study is carried out to evaluate the chemical composition and physicochemical properties of berry leaves, carob and doum tea infusions and their mixtures. Furthermore, the antioxidant activities of these extracts were investigated by scavenging of 1,1 diphenyl-2-picrylehydrozyl (DPPH) radicals. The proliferation inhibition activities on some types of bacteria and yeast were also measured for evaluating the antimicrobial activity of berry leaves, carob and doum tea infusions and their blends. The results showed that carob was characterized by its high protein content. The highest percentage of fi ber was found in doum sample, followed by carob but ash was the highest in berry leaves samples. The levels of most elements were higher in carob sample, when compared with those of berry leaves and doum samples. The highest value of TSS was found in the tea infusions of doum and carob (22.5 Brix), meanwhile, the lowest was observed in the doum tea infusions (10.60 Brix). Acidity of berry leaves, carob and doum tea infusions was higher than that of the berry leaves +doum tea infusions, but lower than that of the berry leaves + carob + doum tea infusions. Total sugars formed the major components in doum and berry leaves + carob tea infusions. Doum and carob tea infusions had signifi cantly higher non-reducing, but lower contents of reducing sugars than the other tested samples. The results indicated that berry leaves + carob + doum tea infusions sample showed higher quality attributes especially color, taste and overall acceptability. The berry leaves and berry leaves + carob tea infusions had a high level of vit. C (11.05 and 10.28 mg/100 g), while it was low in doum tea infusions. Blended samples showed a higher content of total phenol compounds compared to tea infusions of berry leaves, carob and doum. Data indicated that the berry leaves + carob + doum, berry leaves + carob, berry leaves + doum and doum + carob tea infusions samples were good antioxidants with strong DPPH radical-scavenging activity. The results confi rmed that the investigated extracts had good antimicrobial activity, especially against bacteria. Original Paper Section: Food Chemistry

Multiresidue Analysis of Multiclass Plant Growth Regulators in Grapes by Liquid Chromatography/Tandem Mass Spectrometry

A selective and rapid multiresidue analysis method is presented for simultaneous estimation of 12 plant growth regulators (PGRs), namely, auxins (indol-3-acetic acid, indol-3-butyric acid, and naphthyl acetic acid), cytokinins (kinetin, zeatin, and 6-benzyladenine), gibberellic acid (GA3), abscisic acid, and synthetic compounds, namely, forchlorfenuron, paclobutrazole, isoprothiolane, and 2,4-dichlorophenoxy acetic acid (2,4-D) in bud sprouts and grape berries at the development stages of 2-3 and 6-8 mm diameters, which are the critical phases when exogenous application of PGRs may be necessary to achieve desired grape quality and yield. The sample preparation method involved extraction of plant material with acidified methanol (50%) by homogenization for 2 min at 15000 rpm. The pH of the extract was enhanced up to 6 by adding ammonium acetate, followed by homogenization and centrifugation. The supernatant extract was cleaned by SPE on an Oasis HLB cartridge (200 mg, 6 cc). The final extract was measured directly by LC/MS/MS with electrospray ionization in positive mode, except for 2,4-D, GA3, and abscisic acid extracts, which required analysis in negative mode. Quantification by multiple reaction monitoring (MRM) was supported with full-scan mass spectrometric confirmation using "information-dependent acquisition" triggered with MRM to "enhanced product ionization" mode of the hybrid quadrupole-ion trap mass analyzer. The LOQ of the test analytes varied between 1 and 10 ng/g with associated recoveries of 80-120% and precision RSD <25% (n = 8). Significant matrix-induced signal suppression was recorded when the responses for pre- and postextraction spikes of analytes were compared; this could be resolved by using matrix-matched calibration standards. The method could successfully be applied in analyzing incurred residue samples and would, therefore, be useful in precisely deciding the necessity and dose of exogenous applications of PGRs on the basis of measured endogenous levels.

EFFECT OF SALICYLIC ACID AND SO2 GENERATOR PAD ON STORAGE LIFE AND PHENOLIC CONTENTS OF GRAPE (VITIS VINIFERA L. 'BIDANEH SEFID' AND 'BIDANEH GHERMEZ')

Postharvest life of table grapes is usually shortened by berry softening, berry drop, stem browning and its desiccation and also fungal decay. In the present study, the effects of salicylic acid (SA) and an SO z generator pad on grape postharvest storage life and its phenolic composition were studied. Harvested clusters of 'Thompson Seedless' ('Bidaneh Sefid') and 'Bidaneh Ghermez' were treated by salicylic acid (SA) at four concentrations, 0, 1, 2 and 4 mmol/L and stored at 0°C up to two months with or without SO 2 generator pad. SA treatment significantly increased both cultivars' storage life. SA at all three concentrations effectively reduced water loss and fungal decay and increased berry firmness. Furthermore, SA at 2 mmol/L significantly reduced rachis browning rate. In contrast, 4 mmol/L SA slightly showed higher rachis browning than 1 or 2 mmol/L. The SO 2 generator pad reduced fungal decay and rachis browning more effectively than the control. In both SA and SO 2 generator pad treatments total soluble solids, titratable acidity and pH of berries were not different from the control. However, results showed that SA treatment followed by the SO 2 generator pad treatment significantly enhanced both cultivars' storage life and their overall quality. In addition, total phenolic contents were increased by SA treatment during storage. The highest contents were obtained in 4 mmol/l. However, the SO 2 generator pad had no effect on total phenols. The concentrations of quercetin and catechin were higher in SA treated berries. These results demonstrate that SA treatment and the SO 2 generator pad together have better potential for increasing table grapes' storage life and quality.

Impact of Early Leaf Removal on Yield and Fruit and Wine Composition ofVitis viniferaL. Graciano and Carignan

Early defoliation is a novel cultural practice for crop management in grapevines. The effects of timing (prebloom or fruit set) and method (manual or mechanical) of early defoliation on yield and grape and wine composition of <i>Vitis vinifera</i> L. cv. Graciano and Carignan grapevines were investigated. Leaf removal induced a substantial increase in both cluster exposure and canopy porosity. Yield was significantly reduced by defoliation in both varieties. Yield per shoot was reduced between 30 and 70% by manual and mechanical leaf removal prebloom. In both varieties, postflowering leaf removal was ineffective at modifying fruit set, number of berries per cluster, or yield per shoot. <i>Botrytis</i> incidence was also reduced by leaf removal. Prebloom defoliation allowed full recovery of the leaf:fruit ratios to that seen in nondefoliated vines. Grape soluble solids and wine alcohol concentration were not affected by defoliation. Malic acid decreased with leaf removal at fruit set. Genotype-environment interactions on berry acidity variables such as titratable acidity and tartaric acid concentrations were found. Early leaf removal substantially increased anthocyanin and phenol concentration in grapes and wine of both varieties. In Carignan, early leaf removal resulted in heavier berries, which nevertheless had enhanced grape and wine color. These results support the hypothesis that in early-defoliated vines, the relative growth of various berry organs is affected independently from absolute berry mass. Mechanical early defoliation has the potential to be a cost-effective technique to control yield and to improve grape and wine composition.