Grape juice, colorants from

The colors of muscadine grape juice and wine were enhanced by copigmentation with formonetin, biochanin A, and prunetin, the major isoflavonoids extracted from red clove leaves, at ratios of 1 2, 1 4, and 1 8. The 1 8 ratio representing the maximum amount of isoflavonoids used due to its limiting solubility yielded the maximum color enhancement when compared to standard solutions of anthocyanins, at 23 and 60°C. ... 

Red cabbage as a colorant source has been studied for many years. As of 1990 at least one firm has introduced San Red RC, the first commercially available food color derived from red cabbage. The color can be used alone or in combination with other colors to create strawberry, cherry, raspberry, and blueberry tones. By way of proprietary technology, the new dye is claimed to be free of flavor and odor defects, which in the past have been associated with red cabbage. The dye is pH dependent. The color tones move toward blue-red as the pH value increases. San Red RC ranks between cochineal and grape juice in percent or color retention. 

Other colored vegetables can be used to make indicators. Try to make an indicator from grape juice, cherries, onions, beets, apple skins, or tea... 

At a party, a half-gallon at a time can be dumped into the punch bowl so that eveiy-body will get his share. Only don t pour it in directly from the anti-freeze can. An observer might wonder about you. Instead, put some food coloring or Kool-Aid in it to make it look like grape juice or something and put it in two-quart fruit juice cans. 

Joslyn, M. A., Farley, H. B., and Read, H. M. 1929. Effect of temperature and time of heating on extraction of color from red-juice grapes. Ind. Eng. Chem. 21, 1135-1137. 

Another technique to extract color from red grape cultivars is thermovinification. Here, a portion of the must is heated to 50°G/122°F to 60°C/ 140°F and mixed with the skins for a short period of time (Boulton et al., 1996). The must is then pressed prior to inducing alcoholic fermentation. In an interesting study by Malletroit et al. (1991), the effect of pasteurization on the microbiological and sensory quality of white grape juice and wines was investigated. The authors concluded that a pasteurization treatment equivalent to that used in the brewing industry is sufficient to reduce non-Saccharomyces populations prior to alcoholic fermentation without detrimental effects on wine quality. 

The fluid expressed from fully ripened grapes. Most of the grape juice produced in the United States is made from Concord and various other dark-colored varieties of grapes. 

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