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In grapes there are a variety of carbohydrates. In grape berries also contain cellulose, pectins and gums.
In the early ripening grape pectic substances from the solid parts of the berries are partially transformed into juice. With the technical maturity of their content in the juice ranged from 1 to 2 grams per liter. Grape juice obtained from unripe grapes, does not contain pectin.
In the process of compaction of pectin, depending on the fraction of the wort increases. Thus, in the wort of the first fraction of pectin is 0,05%, 0,06% in the second and the third 0.2%. Consequently, the wort is the last fraction contains more pectin than the mash of the first and second fraction. Since pectin is a hydrophilic colloid with a negative charge, then mash and obtained from him the wine is bad lightens up. During the processing of grape pectin is undergoing profound changes, especially in the fermentation process. When fermentation is further disintegration under the action of pectin enzymes of yeast. In yeast polygalacturonase was found. In this regard, the wine is very little pectin, and vintage wines found in the traces. Activity of pectinases in the grapes is much smaller than fungi, of which currently receive pectolytic enzyme preparations. Wines made from grapes treated with pectolytic enzymes, have a good taste.
Nitrogenous compounds of grapes are composed of organic and mineral forms of nitrogen. The former include proteins, amino acids, polypeptides, amines, amides and other nitrogenous compounds, to the second - nitrate, nitrite organic bases and ammonium salts. Grapes and wine dominates the organic form of nitrogen compounds.
. In grape berries in the greatest number contains arginine, aspartic and glutamic acid. |
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