Utilization of grapes

Grapes are small, juicy, sweet fruit that grows in woody vines throughout much of the world, virtually everywhere the climate will support any of the many varieties that exist.

Grapes are mainly used for wine and related fermented products (such as vinegar, wine) with table grapes and raisin a distant second and third, respectively in ranking. Grapes are also utilized to produce unfermented grape juice, jams and jellies.

Much of the world production of grapes ends up as wine, and it is made into a bewildering array of types and price points. Approximately 70 percent of the world’s grape production goes into wine.

Grape juice is derived from grapes that are expressed to extract their juice; separated from the pulp, seeds and skin; and pasteurized at 185 degrees. More expensive grapes may be grown specifically for grape juices and may not necessarily be concentrated or frozen.

Grapes are planted as vines or cuttings from older plants. The cuttings produce arms bearing fruit, the greatest yields coming after 3 years of growth. Properly pruned and cared for, vines produce fruit for many years.
Utilization of grapes

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Storage and fumigation of grapes

Grapes are highly perishable in nature. Therefore they cannot be stored for a long period or transported long distanced at ambient temperatures.

Grapes to be shipped as fresh are packed in wooden crates, then pre-cooled to about 40 ° F (4.4 °C) in railroad cars or refrigerated rooms.

The fruit can tolerate temperatures slightly lower than this, but the margin of safety above freezing the grapes becomes so narrow that for practical purposes, this temperature should he considered the minimum.

Generally, the grapes will be fumigated with sulfur dioxide prior to or during cooling to prevent mold growth. Sulfur fumigation after harvest and /or used of grapes guards have been shown to reduce postharvest losses significantly. The fungus may infect berries in vineyards, particularly when extended periods of rainy weather occur before harvest.

Sulfur dioxide is produced by burning elemental sulfur. It is lightly toxic to fungi and bacteria. The toxicity increases with the percent relative humidity.  The relative humidity of the air should be as high as practicable – 95% if possible.

Grapes that are to be stored for future shipment should be packed in crates, pre-cooled to 36-40 °F (2.2 - 4.4 °C), place in refrigerated storage 29- 32 ° F (-1.67 – 0 °F), and fumigated with sulfur dioxide and should be held in this manner until shipped.

Periodic re-fumigation with sulfur dioxide may be required to prevent spoilage by molds.
Storage and fumigation of grapes  

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