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Third Thematic Workshop. “Dehydration of fruits and vegetables”. Preservation by drying/dehydration
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Third Thematic Workshop “Dehydration of fruits and vegetables”
Preservation by drying/dehydration • The technique of drying is probably the oldest method of food preservation practiced by mankind. The removal of moisture prevents the growth and reproduction of micro-organisms causing decay and minimizes many of the moisture mediated deterioration reactions. • It brings about substantial reduction in weight and volume minimizing packing, storage and transportation costs and enable storability of the product under ambient temperatures, features especially important for developing countries.
Fruit and vegetable natural drying - sun and solar drying • Sun and solar drying of fruits and vegetables is a cheap method of preservation because it uses the natural resource/ source of heat: sunlight. This method can be used on a commercial scale as well at the village level provided that the climate is hot, relatively dry and free of rainfall during and immediately after the normal harvesting period. The fresh crop should be of good quality and as ripe (mature) as it would need to be if it was going to be used fresh. Poor quality produce cannot be used for natural drying.
Drying Process 1- Washing 2- Trimming 3- Slicing 4- Blanching 5- preservation 6- Drying: 6.1- Sun drying 6.2- Shade drying 7- Handling, sorting, packing and storage of dried and dehydrated fruit and vegetables.
dryer/ drying method Factors on which the selection of a particular depends include: • form of raw material and its properties; • desired physical form and characteristics of dried product; • necessary operating conditions; • operation costs.
Drying techniques • Sun drying of fruit crops is still practiced for certain fruit such as figs, apricots, grapes and dates There are three basic types of drying process: 1- sun drying and solar drying; 2- atmospheric drying including batch (tower and cabinet dryers) and continuous (tunnel, belt, belt-trough, spray, drum and microwave); 3- sub-atmospheric dehydration (vacuum shelf/belt/drum and freeze dryers). The scope has been expanded to include use of low temperature, low energy process like osmotic dehydration.
Status and production potential of some fruit and vegetables in Palestine
Grapes: • Grape varieties in Palestine are all essentially related to the European types. • Grape yard areas have not increased significantly over time. Hebron ranks first with 58.8% of the total area, followed by Ramallah and Bethlehem with 26.7%, the Gaza Strip with 7.8%, and finally the northern West Bank (Jenin, Nablus, Tulkarem) with 6.7% (Table 1). • The average production of grapes in Palestine for the last four years is about 52.2 thousand tons, of which Hebron contributed 57.7% to the total.
Varieties Cultivated in Palestine Grape There are over 13 seeded varieties of grapes grown under rainfed conditions in Palestine. These grapes are consumed as table fruit or after processing, in such forms as dibis (molasses), jams, malben (fruit roll), raisins, juice, vinegar, and wine.
Cultivated grapes are classified as follows • White Grapes • Dabouki Zaini Marrawi • Hamadani Beiruti (Romani) Jandali • Red Grapes • Halawani • Black Grapes • Shami Beituni (Baloti Motartash
Stone Fruit Sector in Palestine • Stone fruits comprise nearly 132,246 dunums in the West Bank: 76,281 dunums in the north and 37,539 dunums in the south. In the Gaza Strip, almonds are the major stone fruits cultivated (Table 1). • Stone fruits are grown throughout an extensive manner. Fluctuation between locations, varieties, rainfall, farmer skills. • Surplus stone fruit production is common in Palestine and is generally exported to Jordan or Israel. Peach cultivation, however, does not satisfy local demand, which is supplemented by imports (Table 2).
Fig Cultivation Area and Production • The area of fig cultivation is distributed among the different districts of the West Bank. There is no data recorded about its plantation in the Gaza Strip. The largest area is found in Ramallah, with 52% of the total area, followed by Nablus with 22% (Table 3). There is no significant change in fig areas over time, as the total remains within the average of 23 thousand dunums.
Varieties of Figs in Palestine • More than 50 varieties are found in the Palestine, but only 19 of them are well known. These varieties are classified according to their fruit colors and origin as follows:
Local Varieties • Green or Yellow varieties • Khdari, Biadi, Shnari-Abied, Mowazi, Ajloni, Na'emi, Kbari, Klibi and Sfari. • Green colored or Violet varieties • Khortmani, Slati, Enaqi, Hmadi and Ghzali. • Blackish to Black colored varieties • Kharobi, Swadi, Odicy and Zraqi. • Introduced Varieties • Nasrati, Sultani and Kadota.
Status of Vegetables Production in Palestine • The total production of vegetables in the West Bank in 1990 reached to 69.3 thousand tons, with tomato the most produced with 44.6% , followed by dry onion with 22.6% of total production.
Problems facing dried fruit and vegetables production The major problems are the expense of 1- tillage practices 2- methods of pest and disease control 3- the competition by imported dried fruit and vegetables 4- the small size of land holdings 5- the lack of viable alternatives for farmers to traditional methods of drying, packaging and marketing, which reduce fruit quality and selling prices
Prospects for improving dried fruit and vegetables production in Palestine • Agricultural extension services would improve farmers' knowledge about the best cultivation, picking, drying, packaging, and transportation methods. Improvements in these areas would improve not only fresh fruit and vegetables production and marketing, but also the drying industry. Investigating local varieties more suited to drying would help in stopping the flow of dried fruit and vegetables imports from abroad and make the local market more competitive. • For these tasks, more financial support is needed in the form of loans for crop development.
Drying and dehydration techniques of fruit and vegetables in Palestine Drying and dehydration techniques of fruit and vegetables in Palestine have not been well established. The processes, which are used by the farmers and in the houses, are very old traditional simple and not practical methods. In order to improve these industries a substantial effort should be spend
Basic changes in cultivated area in Palestine 1993-2001 in Dunums
Operational economics establishments in Palestine involved in preservation of fruit and vegetables in 2001
Map of West Bank and Gaza Strip This map shows the two parts of the Palestinian National Authority West Bank and Gaza Strip. The rest of Palestine is occupied by the Israeli army.
Production of field crops used fir drying industries in Palestine by type 2000/2001
Production of field vegetables used for drying industries in Palestine by type 2000/2001
Production of field fruit trees used for drying industries in Palestine by type 2000/2001
Agricultural engineering in West Bank and Gaza Strip in 2001