Amino acids in grape

An extensive review of analytical methods used in determining amino acids in grapes and wine was reported by Ough and Bustos (92). This paper also includes a comprehensive review of the amino acid composition of musts and wine. In addition, Amerine (21), Amerine and Joslyn (2), and Amerine et al. (3) reviewed amino acids in grapes and wine. 

In a study by Dizy and Polo (1996), the majority amino acids in grape must of the Malvar variety were glutamine, arginine, proline and y-aminobutyric acid (GABA). The authors found that the concentration of proline rose during fermentation, while... 

Sisakian, N. M., and Bezinger, E. N. 1950. Amino acids in grape wines (transl.). 

B. cinerea utilizes a significant part of the grape s assimilable nitrogen content, including ammonium and amino acids. In some studies, a significant decrease (by 30-80%) in the total amino acid content has been reported in Botrytis-affected grapes, compared to the healthy grapes (Dittrich and Sponholz, 1975 Dittrich et ah, 1975 Rapp and Reuther, 1971). 

Finally, the relationship between the amino acid composition of grapes and the final aromatic composition of wine has been recently described (Hernandez-Orte et al. 2002, 2006). Therefore, it is possible that in the near future grape juice will be complemented with specific mixtures of amino acids in order to improve the aromatic quality of wine. 

The products of yeast autolysis, such as amino acids may also play a role in wine flavor. The autolysate by-products may also serve as substrates for secondary fermentations. Malic and tartaric acids, the principle organic acids in grape must and wine, can also serve as substrates for secondary fermentation. 

Polyphenolic compounds can interfere in the analysis of red wines, and amino acids in the analysis of grape juices. Consequently several methods for isolating biogenic amines from wines and juices have been proposed liquid-liquid extraction with butanol of the sample preliminarily concentrated and adjusted to pH 1.5 (Almy et al, 1983) in general, for SPE is preferred strong cation exchange (SCX) under... 

Table IV lists the proline, arginine, aspartic acid, glutamic acid, aminobutyric acid, alanine and total amino acid contents of several fruits as reported in selected literature references. A particularly salient reference is that of Fernandez-Flores et al (27) who reported quantities of 15 free amino acids for 22 different fruits. They suggested that the qualitative and quantitative distribution of free amino acids could be characteristic of the individual fruits. There were only smeill variations in the patterns for six different orange samples and seven strawberry samples. They concluded that the qualitative and quantitative distribution of amino acids could be a useful index for determining the authenticity of fruit products. Also, total amino acid content itself can be effectively used since apple and cranberry are very low in total amino acids while grape, blackberry, plum, and peach are relatively high.

The juice from mature grapes contains barely 20% of the total berry nitrogen. The remainder is retained in the skins and seeds, even though the latter are likely to liberate soluble forms of niffogen (ammonium cations and amino acids) in the pulp towards the end of maturation. 

The next step of the biotechnical sequence, yeast fermentation, is of the utmost importance to the chemistry of winemaking as well as to the formation of flavor substances. We have investigated this previously using 14C-tagged compounds (16). Amino acids, for example, enter the yeast fermentation with a quasi biochemical valence with regard to the formation of metabolic side products like alcohols and esters. In that respect, the composition of the fermentation substrate, the grape must, is highly important to the formation of aroma substances by yeasts. 

The literature indicates that most studies pertaining to amino acids have been devoted to grape varieties of the species V. vinifera. In general, investigations have shown that grape varieties of the species V. vinifera and V. labrusca are qualitatively similar in amino acid composition. However, the concentrations of amino acids vary over a wide range, and the varietal effect is significant (83, 93, 94, 95, 96, 97, 98, 99, 100). 

Changes in amino acid composition in grapes are influenced by maturity, season, location, and environmental conditions as reported by several workers (8, 84, 96,101,103, 104, 105). 

Dominguez et al. [71] L-Amino acids D-Amino acids Grapes r,-Amino acid oxidase or D-amino acid oxidase and peroxidase/entrapped in electrode composite matrix by physical inclusion Graphite-Teflon-ferrocene composite electrode/OV vs. Ag/AgCl Ferrocene... 

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