Flash drying of coir pith as an alternative to sun drying

Abstract

Flash drying of coir pith as an alternative to sun drying was investigated. 5 kg of Coir pith was flash dried within the temperature range 120 - 160 °C, at 10 °C intervals using gas velocities 26.1 ± 0.2 ms-1 and 32.0 ± 0.15 ms-1 for multiple cycles. The drying efficiency and quality parameters of dried coir pith and coco discs were determined and compared with sun drying. Drying temperature of 140 °C was found to give the best quality coco discs with optimum quality parameters; volume expansion ratio 5.01 ± 0.21, water retention capacity 4.02 ± 0.10 (w/w), pH 5.95 ± 0.08 and electrical conductivity 330 ± 16 μs/cm. These values were comparable with the quality parameters obtained with natural sun drying. The time required for flash drying was only about 12 ± 1 mins whereas time required for sun drying was 9.1 ± 2 hrs. The Microbial count of undried coir pith, 4.23×106 CFU/g, was reduced by 99% and 89% for flash drying and sun drying respectively. Specific moisture extraction rate (SMER) for flash dryer was found to be 0.399 ± 0.012. The results of this study suggests flash drying as a good alternative to sun drying for moisture removal from coir pith.