Acids In Grape Juice Research Articles

Aminokiselinski sastav mošta nekih sorata vinove loze (Vitis vinifera L.) Hrvatske

Free amino acids in grape juice are important as nitrogen source for yeast strains during alcoholic fermentation. The aim of this research was to determine amino acid profiles in musts from nine grapevine cultivars (six white and three red). The cultivars were located in a homogeneous soil and climatic zone of Bilogora growing hill (West continental region, Prigorje–bilogora subregion), grown on the same training system. The experiment was conducted in vintage 2015. The results showed significant influence of grape cultivar on the amino acids composition in musts of white and red grape cultivars. Arginine was dominant in most analyzed varieties of amino acids. The highest concentration of arginine in white cultivars was measured in Chardonnay must (470.18 mg/L) and in red cultivar must from Saint Laurent (280.65 mg/L). Statistically significant difference was also found in the total amino acid composition of white and red cultivars. The highest concentration of total amino acids in white cultivars was determined in Manzoni juice (1639.51 mg/L) and among the red cultivars in Pinot noir juice (1173.12 mg/L).

Marker Assisted Selection of Malic-Consuming Saccharomyces cerevisiae Strains for Winemaking. Efficiency and Limits of a QTL's Driven Breeding Program.

Natural Saccharomyces cerevisiae yeast strains exhibit very large genotypic and phenotypic diversity. Breeding programs that take advantage of this characteristic are widely used for selecting starters for wine industry, especially in the recent years when winemakers need to adapt their production to climate change. The aim of this work was to evaluate a marker assisted selection (MAS) program to improve malic acid consumption capacity of Saccharomyces cerevisiae in grape juice. Optimal individuals of two unrelated F1-hybrids were crossed to get a new genetic background carrying many “malic consumer” loci. Then, eleven quantitative trait loci (QTLs) already identified were used for implementing the MAS breeding program. By this method, extreme individuals able to consume more than 70% of malic acid in grape juice were selected. These individuals were tested in different enological matrixes and compared to their original parental strains. They greatly reduced the malic acid content at the end of alcoholic fermentation, they appeared to be robust to the environment, and they accelerated the ongoing of malolactic fermentations by Oenococcus oeni. This study illustrates how MAS can be efficiently used for selecting industrial Saccharomyces cerevisiae strains with outlier properties for winemaking.

Study About HPLC Method Elaboration and Validation for Acid Lactic Assay in Grape Juice Fermentation Process

In the present study, a simple and fast HPLC procedure has been developed for determination of a wide range of lactic acid concentrations. During the lactic acid analysis, the analytic column,YMC-Pack ODS AQ, was operating at 20oC. The mobile phase, 0.03% H3PO4:acetonitrile (88:12), was delivered isocratic, at a flow rate of 0.5 mL/min, in a 25 min run. The method was validate. The method could successfully used to quantify lactic acid in grape juice during fermentation.

Study About HPLC Method Elaboration and Validation for Acid Lactic Assay in Grape Juice Fermentation Process

In the present study, a simple and fast HPLC procedure has been developed for determination of a wide range of lactic acid concentrations. During the lactic acid analysis, the analytic column,YMC-Pack ODS AQ, was operating at 20oC. The mobile phase, 0.03% H3PO4:acetonitrile (88:12), was delivered isocratic, at a flow rate of 0.5 mL/min, in a 25 min run. The method was validate. The method could successfully used to quantify lactic acid in grape juice during fermentation. Keywords: Lactic acid, HPLC, grape juice

Optimization of deacidification for concentrated grape juice.

Excessive organic acids in grape juice will not only result in poor taste but will also cause turbidity and sedimentation. Tartaric acid exerts the most significant acidity among all organic acids in grape juice. In this study, we used tartaric acid as the main target and anion‐exchange resin to remove tartaric acid from concentrated grape juice. Factors influencing the removal process were optimized by liquid chromatography with ultraviolet detection and statistical analysis for optimal deacidification of concentrated grape juice. Use of the anion‐exchange resin 335 treat the concentrated grape juice at a ratio of 1:6 (2:11.98) at 15.57°C for 4.35 hr. The tartaric acid removal rate reached 69.01%; the anion‐exchange resin 335 demonstrated the best removal effect.

Pre-fermentative supplementation of fatty acids alters the metabolic activity of wine yeasts

Fatty acids play important roles in the maintenance of cell membrane, viability and overall metabolism of wine yeasts (particularly Saccharomyces cerevisiae) during adverse winemaking conditions. We previously showed that linoleic acid supplementation markedly affect aroma compound production of S. cerevisiae wine strains. However, very little is known about how other commonly found fatty acids in grape juice modulate the growth and metabolism of S. cerevisiae. We aimed to determine the individual effect of five fatty acids on fermentation patterns and metabolism of two wine yeast strains (S. cerevisiae EC1118 and X5). Microvinification was performed at 15 °C by supplementing a grape juice (individually) with three different concentrations of saturated (palmitic acid), unsaturated (oleic, linoleic and γ-linolenic acids) and short-chain (hexanoic acid) fatty acids. Metabolite profiles of the resulting wines were determined using Gas-chromatography coupled to Mass-spectrometry (GC–MS). Our data show that the addition of γ-linolenic acid to the juice caused the production of higher amounts of amino and organic acids (except isoleucine and 2-oxoglutaric acid) in wines when fermented by EC1118, while palmitic acid supplementation showed similar trends when fermented by X5. The effect of linoleic acid was independent of yeast strains and we observed a global reduction of amino and organic acids (except pyruvic acid) while increased production of most of the fatty acids other than the supplemented ones. Our data clearly suggest that pre-fermentative supplementation of different fatty acids indeed influenced the growth and metabolism of wine yeasts in a different way. Thus, attention needs to be paid not only to the wine yeast strain used during the winemaking but also to the overall grape juice composition, including fatty acids, to obtain the desired wine characteristics.

Effect of free fatty acids and lipolysis on Sauvignon Blanc fermentation

Background and Aims The volatile thiols, such as 3-mercaptohexanol, 3-mercaptohexyl acetate and 4-mercapto-4-methylpentan-2-one, are major aroma compounds responsible for the distinctive tropical notes (passionfruit and grapefruit) in New Zealand Sauvignon Blanc wines. Previously, it was observed that traces of linoleic acid in grape juice can significantly affect the development of these volatile thiols and other aroma compounds in wine. Here, we examined the effect of the fatty acids commonly found in Sauvignon Blanc grape juice as well as juice lipid lipolysis on the development of aroma compounds in the resulting wines. Methods and Results Experiments were performed to increase the total free fatty acid concentration in grape juice through juice treatment with acidic lipase from Aspergillus niger and through co-cultured fermentations with non-Saccharomyces lipase-secreting yeasts. We observed a significant reduction in the production of 3-mercaptohexyl acetate in fermented wines upon supplementation with linoleic acid and lipase. Supplementation with lipase increased the concentration of 3-mercaptohexanol and all ethyl esters detected, while reducing the development of acetate esters. Co-cultured fermentations also affected the development of many classes of aroma compounds. Conclusions This study demonstrated that the aroma profile of wines could be effectively manipulated by altering the amount of free unsaturated fatty acids in grape juice through lipolytic enzyme supplementation or co-fermentation with non-Saccharomyces lipolytic yeast species. Significance of the Study The key findings of this study may lead to new winemaking strategies through the manipulation of the lipid component of grape juice.

Novel Wine Yeast for Improved Utilisation of Proline during Fermentation

Proline is the predominant amino acid in grape juice, but it is poorly assimilated by wine yeast under the anaerobic conditions typical of most fermentations. Exploiting the abundance of this naturally occurring nitrogen source to overcome the need for nitrogen supplementation and/or the risk of stuck or sluggish fermentations would be most beneficial. This study describes the isolation and evaluation of a novel wine yeast isolate, Q7, obtained through ethyl methanesulfonate (EMS) mutagenesis. The utilisation of proline by the EMS isolate was markedly higher than by the QA23 wild type strain, with approximately 700 and 300 mg/L more consumed under aerobic and self-anaerobic fermentation conditions, respectively, in the presence of preferred nitrogen sources. Higher intracellular proline contents in the wild type strain implied a lesser rate of proline catabolism or incorporation by this strain, but with higher cell viability after freezing treatment. The expression of key genes (PUT1, PUT2, PUT3, PUT4, GAP1 and URE2) involved in proline degradation, transport and repression were compared between the parent strain and the isolate, revealing key differences. The application of these strains for efficient conduct for nitrogen-limited fermentations is a possibility.

Hydroxycinnamic acids as affected by different fertilization of Rebula grapevines

The phenolic composition of white grapes is important since browning reactions may dramatically compromise the overall quality of musts and wines. Only few scientific contributions are available, which investigated how fertilization can influence this class of compounds. Thus, the aim of this work was to examine the effects of NPK soil fertilization coupled with soil or foliar applications of Mg, Fe, and Zn on the concentrations of K, Mg, Fe, and Zn of grape berries and leaf petioles of potted Rebula grapevines (Vitis vinifera L.), also revealing the change of hydroxycinnamic acids in grape juice. The results obtained over the three-year study (2009–2011) showed that NPK fertilization positively affected K and Zn concentrations of petioles and grape berries, and negatively Mg. In addition, K (synergistic) and Mg (antagonistic) had an influence on Zn uptake. Our findings suggest that the supply of NPK was profitable for a reduction of trans-caftaric acid in grape juice, while only few differences were observed with further application of nutrients.

Diurnal Changes in Amino Acid Concentrations in Riesling and Chardonnay Grape Juices and a Possible Role of Sunlight

Diurnal changes in the concentrations of amino acids in grape juice (Vitis vinifera L.) were investigated during mid to late ripening over three consecutive years. To avoid the effect of harvest shock, samples were prepared within 15 min after grape berry picking. Changes in the amino acid concentrations of juices were classified into three patterns. The concentrations of aspartic acid (Asp) and glutamic acid (Glu) decreased during the morning and gradually increased at night. The alanine (Ala) concentration increased during the morning and decreased at night. The amino acid peak times were 0600 to 0900 hr for Asp, 0600 to 0700 hr for Glu, and 1300 to 1900 hr for Ala for Riesling harvested from 31 Aug to 1 Sep 2010. Some of the other amino acids, such as phenylalanine, serine, proline, and threonine showed minimal or no diurnal changes in concentration. Yeast assimilable nitrogen (YAN) showed minimal daily changes. During cloudy days, these diurnal changes diminished. When grape clusters were shaded with aluminum foil, the patterns of amino acid concentrations did not change, with some exceptions. Photosynthesis is proposed as the main contributor to these changes, since minimal changes were observed under cloud cover. Moreover, leaf rather than berry photosynthesis is likely an important factor in the composition of berry amino acids.

Determination of caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seeds by ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry

An ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry (UPLC-MS/MS) method was developed for the determination of hydroxycinnamoyltartaric esters, such as caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seed. The target analytes were separated on a Waters UPLC HSS T3 column (150 mm x 2.1 mm, 1.7 microm) at 35 degrees C with gradient elution at a flow rate of 0.3 mL/min. The grape juice was freeze-centrifuged, the supernatant was diluted with 20% methanol. The grape peel and grape seed samples were extracted with 80% ethanol. The extract was cleaned-up on-line with the analytical column by valve switching technology. The mobile phases were water-acetonitrile (both containing 0.1% formic acid). The identification and quantification were achieved by MS/MS in multiple reaction monitoring (MRM) mode via negative electrospray ionization. As lack of commercial standards, p-coutaric acid and fertaric acid were quantified by caftaric acid equivalent. The developed method showed a good linearity over the range of 25-2 000 microg/L with good correlation coefficient (r2 = 0.998 9). The limit of detection was 0.25 microg/L, and the limit of quantification was 25 microg/L. The average recoveries of caftaric acid were between 97.7%-99.5% and the precisions were within 2.5% at the spiked levels of 250, 750 and 1 200 microg/L. The working solutions were stable for 74 h at room temperature. The results showed that there are significant differences of hydroxycinnamoyltartaric esters distribution in grape juice, peel and seeds. Therefore, this method, owing to its simplicity, rapidity, good recovery, high sensitivity and accuracy, can be used for the analysis of caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seeds.

Berry shrivel of grapes in Austria – Aspects of the physiological disorder with cultivar Zweigelt (Vitis vinifera L.)

Berry shrivel (BS) is a physiological disorder of grapevine that affects berry development with decreases in quantity and quality of the crop. The causes of BS are unknown and no treatment exists for prevention or cure. BS seems to occur temporally and spatially at random in vineyards even among and within vines. The detailed description of symptoms and their development is an important step towards the understanding of the molecular background behind BS. Herein symptoms of BS are described with parameters aiming to clearly differentiate between healthy and BS grapes. Analyses were conducted on Vitis vinifera (L.) cv. Zweigelt in 2009/2010 at five Austrian vineyards. Berry diameter and berry deformability were severely reduced by BS, and this effect was observed on whole clusters. BS berries had significantly reduced contents of soluble solids and total anthocyanin concentration 67–73 days after anthesis (DAA), both representing key markers for the early detection of BS clusters. A systemic effect of BS on other no symptoms showing clusters of the same plant could not be observed. Additionally the concentrations of several amino acids in grape juice were affected by BS: thirteen were reduced, two were induced and four did not change significantly.

Quantification of glutathione, catechin and caffeic acid in grape juice and wine by a novel ultra-performance liquid chromatography method

This research aimed at the development and validation of an ultra-performance liquid chromatography (UPLC) method for the quantification of glutathione (GSH) in grape juice and in white wine after derivatisation with para-benzoquinone. The phenolic compounds catechin and caffeic acid that occur in white wine and have antioxidant effects, are also quantified in the same analysis. Catechin is the basic monomeric unit of grape and wine tannins and caffeic acid, when esterified with tartaric acid, plays a relevant role in Grape Reaction Product (GRP) formation.The analytical method proposed showed good linearity, repeatability and intermediate repeatability, as well as high recovery (>85%). It was applied for the quantification of GSH, catechin and caffeic acid in South African juices (12) and white wines (43).This novel method will have a large impact on the time and costs of the analyses for the wine industry through enabling rapid routine quantification of GSH, catechin and caffeic acid.

Simple determination of main organic acids in grape juice and wine by using capillary zone electrophoresis with direct UV detection

An accurate, simple and rapid capillary zone electrophoresis (CZE) method with direct UV detection has been set up for the determination of main organic acids in grape juice and wine. The determination of tartaric, malic, and citric acids in grape juices and tartaric, malic, succinic, acetic, lactic and citric acids in wines can be achieved in less than 3 min with only a simple dilution and filtration treatment of the sample. Validation parameters of the method as detection and quantification limits, linearity, precision (intraday and interday analysis) and recovery were also studied in grape juice, white wine, rose wine and red wine, separately. The proposed method decreases the analysis times of the previous reported CZE methods and allows the rapid control of the grape maturity, the winemaking processes and the detection of wine alterations and/or illnesses.

Spectrophotometric Assay for Arginine in Grape Juice and Must

An assay for arginine was developed that involves its separation from other amino acids by cation exchange followed by a spectrophotometric quantification as an <i>o</i>-phthaldialdehyde/n-acetyl-L-cysteine derivative. Arginine is usually the most abundant yeast assimilable amino acid in grape juice and must, and a natural precursor to ethyl carbamate (EC) formation in wine. Ethyl carbamate is a naturally occurring component of all fermented foods and beverages. Because EC has shown a potential for carcinogenicity when administered in high doses in animal tests, the wine industry is interested in reducing EC levels in their products. Elevated arginine concentrations in grape juice and must can lead to a increased potential for EC concentrations in wine. The arginine molecule has an isoelectric point above all other amino acids relevant to grape juice and wine. The assay uses a strong cation exchange cartridge to isolate arginine from all other amino acids in grape juice, and a modified version of a previously published spectrophotometric assay for yeast assimilable amino acids to measure the isolated arginine. The effects of potential grape juice-specific interferences in both model solutions and real musts were investigated and eliminated. The method was validated by determination of linear response to known standards, recovery of spiked samples and correlation to a reference method (R² = 0.987). In addition to its accuracy and speed, the method, termed ARGOPA for "arginine by <i>o</i>-phthaldialdehyde", is robust, simple and inexpensive enough to be used under commercial winemaking conditions. A winery laboratory procedure for the assay can be downloaded at &lt;http://wineserver.ucdavis.edu/ oldsite/argopa99.pdf&gt;.

An Improved Capillary Electrophoresis Procedure for the Determination of Organic Acids in Grape Juice and Wine

Major organic acids in grape juice and wine were separated and quantified by an improved capillary electrophoretic (CE) method. Indirect UV detection with 2,6-pyridinedicarboxylic acid as a background electrolyte buffer (pH 5.60) was used in this method. Although indirect UV generally uses low buffer concentrations, in this case an adequate buffer capacity was required to ensure reproducible migration times due to the pH dependency of the charge and thus mobility of the organic acids. Tartaric, malic, citric, succinic, acetic, and lactic acids were baseline resolved in 7.3 minutes by reversing the electroosmotic flow. Sample preparation was 0.45 µm filtration and a 40-fold dilution with glyoxylic acid as the internal standard. The accuracy and precision of the CE-method were better than ± 2% at 2500 mg/L. Migration time reproducibility of better than ± 1% was achieved. All acids gave linear detector responses from 5 to 125 mg/L (diluted 40-fold) with the exception of succinic (5 to 20 mg/L) and acetic (5 to 18 mg/L). This CE method enables rapid (&lt; 13 minutes total analysis time) and simultaneous analysis of major organic acids without sample cleanup in grape juice and wine for assessing the stability of products during manufacturing processes.

On-line dialysis with HPLC for the automated preparation and analysis of amino acids, sugars and organic acids in grape juice and wines

A reproducible and high throughput technique is described for on-line clean-up and routine analysis of small molecules such as amino acids, sugars and organic acids in grape juice and wines. A fully automated sample processor (ASTED) provides an efficient way of preparing and cleaning-up raw liquid food samples. Following the usual preparation steps like dilution, addition of internal standards, mixing and derivatization, an on-line dialysis procedure is performed before HPLC analysis, to remove macromolecular and microparticulate interferents resulting from complex matrices. Eighteen amino acids, six organic acids, two sugars, ethanol and glycerol have been determined using two methods. Analytical data are provided both for a grape juice and a red wine.

Proposed descriptors for organic acids to evaluate grape germplasm

A total of 259 grapevine accessions consisting of 169 varieties, 81 bred lines, 5 rootstocks and 4 clones of 2 wild species were surveyed for content and composition of organic acids in grape juice. Free acid content ranged from 0.13 g to 2.79 g/100 ml, and total acid content ranged from 0.36 g to 3.95 g/100 ml. The acid contents (both free and total acid) of the varieties and bred lines were lower than those of rootstocks and wild species. Furthermore, ratios of free to total acid of the varieties and bred lines were significantly lower than those of rootstocks and wild species. As tartaric and malic acids were major components in acid composition, the ratio of tartaric to malic acid (designated as β ratio) varied from 0.25 to 7.23, and the varieties and bred lines were superior to the rootstocks and wild species in the β ratio. Varietal difference in the β ratio was also observed in the cultivated species (Vitis vinifera and hybrids of V. labrusca x V. vinifera). The ripening period was associated with sharp decrease in free acid content, while β ratio was continued to increase. Although their change during ripening was remarkable, less variation in free acid content and the β ratio was observed near the ripening stage. The variations in free acid content and the β ratio as the descriptors between years were not negligble, indicating that evaluation for the two descriptors should be made in several years, at least three years.

Deacidification of grape juice with derepressed mutants of the yeast Hansenula anomala

Transport and utilization of malic acid by the yeast Hansenula anomala are subject to glucose repression. Derepressed diploid mutant strains were obtained by hybridization of derepressed haploid mutant strains of opposite mating type. Six diploid mutant strains displayed derepressed behaviour with respect to malic acid utilization in the presence of glucose up to 30% (w/v). Three of these diploid mutant strains, as compared with the parent strain, were able to degrade completely malic acid in grape juice without fermenting the sugars. In addition, using one diploid mutant strain together with a strain of the wine yeast Saccharomyces cerevisiae, it was possible to carry out a mixedmicrovinification in which deacidification occurred simultaneously with alcoholic fermentation.

Determination of Tartaric, Malic, and Citric Acids in Grape Juice and Wine Using Gradient Ion Chromatography

A gradient ion chromatographic (IC) method with conductivity detection and chemical suppression was evaluated for the separation and quantification of major organic acids in grape juice and wine without prior sample clean-up. Tartaric, malic, and citric acids were the major acids of concern in this investigation. By using a Dionex OmniPac PAX-500 column, sample preparation was a simple 50-fold dilution with 0.45 micron filtration and direct injection. Analysis time was 35 minutes. The accuracy of the IC method was better than ± 1.0% at the 2.5 g/L concentration level. The precision for a dark red juice was ±2.0%. The results of the IC method were comparable to other published colorimetric and enzymatic methods. This IC method enables rapid and simultaneous analysis of tartaric, malic, and citric acids in grape juice and wines for quickly assessing the stability of products during manufacturing processes.