SOLAR DRYING OF GRAPES

ABSTRACT Mass losses and low quality are the most serious disadvantages of traditional grape drying methods. For the production of high quality raisins an increase in the drying rate is required and the grapes should be protected from rain, dust and insects during drying. Under the terms of a joint German-Greek research program low-cost solar grape dryers were developed in the Institute of Agricultural Engineering of Hohenheim University and were tested in Greece in cooperation with the Crete Agricultural Research Center. The required data basis for optimizing solar grape dryers was obtained by additional laboratory tests measuring the influence of various drying parameters on drying rate and quality. Tests with the solar dryers have shown that it is possible to reduce the drying time and improve the quality significantly compared to the traditional drying methods. Also mass losses due to rain can be prevented.