Effect of solar drying using a natural convective solar drier on bacterial load and chemical composition of bayad (Bagrus bayad) fish flakes

Abstract

Solar drying experiments  of bayad (Bagrus bayad) fish flakes using a natural convective solar drier were conducted at Food Research Centre (FRC), Agricultural Research Corporation, Shambat, Sudan. During June-August, 2008 and May-June, 2009. Tthe objectives of the present study were  to investigate the effect of solar drying using a natural convective solar drier on bacterial load and the percentages (%) of chemical composition of bayad fish flakes. These are percentages  of  fats, protein, fibers and ach contents .The results showed that, there was a considerable decrease in bacteria present in the dried fish compared to the  fresh one from the same fish. this could be  attributed  to the increase in temperature inside the  solar collector of the drier . The total viable count of bacteria decreased from (1.13×108 cfu⁄g) in fresh fish to (2.16×106 cfu ⁄g) in solar dryed  fish. This means that, solar drying of fish affected bacterial load considerably due to the elevated temperature inside the solar drier. Regarding chemical compositions of fish flakes, the results showed that, the amount of fats as a percentage  were similar in both fresh and dried fish flakes, fibers content were nil in both fresh and dried fish, while protein  content was less in dried fish flakes .Ach content was increased in dried fish  from 7.27% to about 30.68%.The increase in ach and decrease in protein were resulted from the addition of salt as a pre-treatment before fish were dried, so that the percentage of inorganic matter was increased (salt) and the percentage of  organic matter was decreased (protein).