Crushing of grapes

After crushing of grapes, anthocyanins were extracted from grape skins during alcoholic fermentation. A peak concentration of 29S mg/L of the dominating anthocyanin malvidin-3-gIucoside (M3G) was achieved after seven days, after which the skins were removed by pressing (Table 1). 

To show correlation between occurrence of malo-lactic fermentation and bacterial inoculation, and to show consistency of results among the control lots and inoculated lots, it is imperative that the division of lots be made before alcoholic fermentation. For red wines, great care must be taken to obtain equitable distribution of the crushed grapes in each of the lots. The inconsistency in the results mentioned above may have been caused by variation in amounts of grape skins during the alcoholic fermentation with the accompanying effect on fermentation temperature, sulfur dioxide concentration,. pH after pressing, and concentration of nutrients (55, 56). 

FIGURE 5.7 Crushing the grapes in the lagar. Photography of Rui Cunha from the collection of the IVDP, IP. 

Disadvantages of machine harvest include increased juice loss, particularly with certain varieties, tendency of leaves to get into harvested fruit (which varies with the type of harvester), potential for inclusion of second crop fruit with ripe grapes, and, because of crushing of berries during harvest, more potential oxidation and phenolic extraction from skins. Much work has... 

Wineries using this new equipment are able to produce up to 180-190 gross gallons of juice and wine per ton of grapes crushed. Individual crush-... 

Must and Wine Yield. The wine gallon yield per ton varies with type of grape, whether white or black. Total wine gallon yield is composed of three fractions. The main volume is the free-run juice that flows from the crushed grape second is the drain screen juice that separates from the pomace, which already has had the free-run juice removed and third is the press juice from the tight squeezing of the screen-drained pomace that was conveyed to the grape press. 

Grape seeds are rich in polyphenols, especially flavanols (catechin, epicatechin) and gallic acid (Meyer et al., 1997). When grape extracts are prepared after crushing of the seeds, increased levels of phenols are obtained compared with extracts prepared with intact grape seeds. In particular, flavan-3-ol levels increased significantly. The antioxidant activity, as measured by the ability to inhibit LDL oxidation, also increased when the seeds were crushed prior to extraction. 

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