Table grape sugar concentration

Increases in yield have long been known to affect grape sugar concentration negatively (Table 10.10). This problem is especially troubling in vineyards that use varieties close to... 

In comparison with the wine varieties, table varieties usually are harvested and consumed at lower concentrations of sugar, typically around 150 grams per liter rather than the 220 to 250 of wine varieties. Acid concentrations, similarly, are usually lower, and in the range of 4 to 6 grams per liter rather than the 8 to 10 of wine varieties. Overall quality in the palate factors of a table grape depends upon a harmonious balance of the elements making up the flavor ( ). 

The experiment in Table 3.6 shows the effect of the addition of alcohol to grape must. It slows the initiation of fermentation and limits the assimilation of nitrogen and the formation of alcohol. Yet the yeasts can continue their activity up to a higher alcohol content, as long as the inhibitory action of ethanol is not excessive. In this experiment, the variation of the glycerol concentration represents significant metabolic modification. As seen in Section 3.4.1, ethanol intensifies the inhibitory effect of an elevated sugar concentration in must. 

Table 3.13. Evolution of the fomentation of a grape mnst containing a high sugar concentration (270 gd) according to aoation conditions (Rib6reau-Gayon et al., 1951)...

The quick or competitive procedure for making sweet table wines depends on sweetening a dry table wine with a very sweet blending wine or with sugar or grape concentrate and some procedure of sterilization which ensures that no viable yeast cells are present in the closed bottle. The simplest is pasteurization of the blend after it has been bottled. This technique, however, is not favored as it tends to give the wine a cooked aroma and taste. 

Table II shows that sucrose levels are highest in peach fruit and very low in blackberry, cherry, and grape. The % C.V. for sucrose content for many of the fruit samples is extremely high, most likely because of enzymic or chemical hydrolysis. The average sucrose content of plum fruit is 38 of total sugars, while processed plums contain only 1. Presence of large quantities of sucrose in prune juice has, in fact, been used as an indication of adulteration ( ). Cherries and grapes contain invertase Cllj 12) which may account for sucrose not being detected in some samples and may also explain the high % C.V. for those fruits. In examining apple Juice concentrates, we did not detect sucrose in seven-fold concentrates whereas we did in fo ar-fold apple concentrates (7.) > the time-temperature conditions allowing for complete hydrolysis in the more concentrated product.

Raisins contain only 17% water whereas grapes contain about 80% water. Therefore, many of the nutrients in grapes are more concentrated in raisins. Each 100 g (about 3 1/2 oz) of raisins provides 289 Calories (kcal) of energy, 2.8 mg of iron, and 678 mg of potassium. The calories in raisins are derived primarily from the naturally occurring sugars (carbohydrates). More oomplelB information regarding the nutritional value of raisins is presented in Food Composition Table F-21. 

The enological profile of must obtained from botrytized grapes is specific (Table 10.11). This juice is very rich in sugars but its acidity is similar to that of juice obtained from healthy grapes. The tartaric acid concentration is often even lower and the pH higher (from 3.5 to 4.0), attesting to the... 

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