A Comparative Study Of Solar And Direct Sun Drying Of Pre-Treated Green Plantain

ABSTRACT

A comparative study of solar and direct sun drying of pre-treated green plantain was conducted. A distributed – type natural circulation solar dryer fabricated from locally available materials and direct open sun drying were used to investigate the drying characteristics of green plantain slices between January and February, 2012. The fingers harvested weekly from the 9th to 13th week were washed, peeled and cut into slices (1cm thickness). Each batch of the sliced plantain fingers were pre-treated by soaking in citric acid, sodium metabisuphite and blanching prior to direct sun and solar drying. The untreated plantain flour served as control. The thermal properties which included starch gelatinization temperature and enthalpy were by Rapid Visco Amylograph and Differential Scanning Calorimetry. The shelf stability of the flour samples was also investigated over a period of 6 months by monitoring the microbial load. Assessment of the functional properties showed no significant differences in the oil absorption capacity, gelling point and bulk density of the flour samples irrespective of harvesting time and pre-treatment. However, there were significant differences in water absorption (p< 0.05) with the sodium metabisuphite treated sample having the highest value of 2.74ml/g. Higher pH values were recorded for flours treated with sodium metabisulphite and blanched with values ranging from 6.87 – 7.54. Also, in the swelling index (P