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چکیده
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Drying is probably the oldest method of preserving fruits and initially was used as a way of storing foods for the low supply season. Dried grapes, commonly known as raisins, are of a great economic importance for many countries. Combinations of different harvest date (four harvest dates) with post harvest alkaline emulsion (three alkaline solutions) were tested in `Paycamy’ grape green raisin production. Some raisin quantitative and qualitative characteristics such as: yield, drying ratio (fresh: raisin yield), raisin wastes, sugar content, price, color, homogeneity of color, raisin size, alkaline solution residues and surface texture of raisin (shrinkage) were measured. Results showed that harvest date and post harvest treatment affected yield, drying ratio (fresh: raisin yield), raisin wastes, sugar content, price, color, homogeneity of color, raisin size, alkaline solution residues and surface texture of raisin. Harvest date results showed that grape °Brix and raisin sugar content increased from 15.5 to 21 and 53% to 62% respectively. In addition, fourth harvest yield increased raisin yield up to 30% compared to the first harvest.
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