بررسی تعیین زمان برداشت و شرایط بهینه خشک کردن مقدماتی سیر

Proper drying is essential to successful marketing in regions which cultivated garlic and most serious postharvest losses result from improper drying. For this reason White garlic population of two regions i.e. Hamedan and Ramhormoz were cultivated on Complete Block Design with three replications. After the cut off irrigation, garlic populations were harvested at three stages, when approximately 70 percent of the top and the whole leaves of garlic turned yellow and at third stage all leaves turned dry and brown and fell over on the field. After harvesting all bulbs dried at natural condition and artificial state at 35, 45 and 55 degree C. Effect of harvesting stage and drying conditions on the garlic shelf life were investigated during 6 months and qualitative and quantitative factors i.e. moisture content, pyruvate, color and texture in addition to weight loss and spoilage were measured monthly. Results during two years showed that there was no significant difference between yield of Hamedan garlic population during three stages of harvest, but differences between the other population were significant and the yield of Ramhormoz garlic was less than the other. The pyruvate, color and texture contents of garlic populations showed that the garlic harvesting from the first stage is possible, although the moisture contents of garlic bulbs were high enough to dry before storage. Effect of different conditions of Hamedan garlic drying on drying time showed that natural drying time was longer than artificial drying. Artificial drying rate of Ramhormoz population at 45 and 55 degree C and natural condition was more than 35 degree C. Drying time of both populations during the first stage of harvesting because of the high moisture content was more than another stages. Drying time of Hamedan garlic increased with flourishing temperature and some cloves became yellow, soft and sticky at 55 degree C. This phenomenon was occurred at 45 and 55 degree C for Ramhormoz garlic. Therefore at these temperatures, garlic should dry until the stem moisture content equalized 40 3 percent and residue should be removed by natural drying. During the drying of postharvest garlic populations, the moisture content of cloves was relatively constant, while that of the skins and stem rapidly decreased. After curing, moisture contents of the cloves, skins and stems were 64 1, 20 2 and 15 4 percent respectively. Therefore the measurement of the moisture content of the skins, stems and the neck diameter of garlic can be used for ending postharvest drying. Effect of drying on some quality factors showed that at low temperatures, the pyruvate contents and color changes decreased. Qualitative and quantitative factors at the end of storage period showed that for Hamadan garlic, harvesting at the first stage, drying at 35 degree C or natural conditions and the second stage, drying at 35 or 45 degree C or natural conditions are the best and for Ramhormoz garlic, harvesting at the second stage, drying at 35 degree C or natural conditions is recommended.

کلیدواژه ها:

سیر سفید ، تاریخ برداشت ، خشکاندن ، عمل آوری ، انبارداری ، همدان ، رامهرمز