process parameters optimization for producing of round and long raisin concentrate in khorasan region

since a long time ago raisins has been considered as an exporting item iniran, in which only 15-20 percent of raisins are consumed and the remaining is exported at a low price. also, until 20 years ago,iranwas one of the most important exporters of raisins to european and asian countries. unfortunately because of retarded technology, lack of modern agricultural methods and also lack of suitable processing and unsuitable packaging,iranlost global markets. today, in the world especially european and american countries produce different byproducts such as pasta and concentrate from raisins. unfortunately, in spite of existing suitable raw material, no serious effort has been taken in our country. therefore, the method of extracting raisins concentrate has been studied. two levels of solvent (1:1 and 2:1), three levels of extraction temperature (60°c, 70°c and 80°c), and three levels of concentration temperature (50°c, 60°c and 70°c) were the treatments. finally physicochemical characteristics of the obtained concentrate such as color, viscosity, percentage of reducing sugar, acidity and the microbial tests (mould and yeast) were measured. the analysis was performed on the basis of factorial in the form of completely randomized design (crd) andduncan's multiple range test (dmrt) was used for the comparison of the means. statistical analysis of results showed that optimal conditions for production of concentrate is round raisins when the solvent ratio was 2:1 with extraction temperature of 60°c and then concentration temperature of 50°c. round raisin is cheaper than the long one, and it is more economical to concentrate production. furthermore, round raisin has more aroma and lesser color density with increasing the temperature of concentration and extraction. finally, according to mentioned factors the concentrate of round raisin is recommended.