Drying of waste grains flour of annatto by using solar energy

Abstract

  This study is aimed at drying annatto seed powders produced from seeds with and without oil used in bixin extraction. Drying was done at night, using a solar energy dryer. The drier consists of a system of solar panels that heat water, which is transferred to a thermal reservoir from where it is used as heat source for drying during the night. The waste grain flour of annatto with initial moisture content of approximately 20% w.b. was dried by approximately 5% w.b. The samples were split into two batches: Exposed to external environment and placed in the drier. The drying kinetic data were fitted by five mathematical models. The drier showed effectiveness in the drying of annatto grains flour at night with difference of more than 10% of moisture content in relation to the samples exposed to external environment. Powders obtained from seeds containing oil took approximately 40% longer to dry than those without oil. The mathematical models assessed satisfactorily represented drying behavior. The highest values of diffusivity were found in dehydrated samples in the drier.   Key words: Bixa orellana L., agroindustrial waste, nocturnal drier.