QUALITY EVALUATION OF FOUR BANANA CULTIVARS DRIED IN A GREENHOUSE DRYER OPERATED UNDER DIFFERENT ENERGY MODES

Florence G Kiburi; Christopher L Kanali; Gareth M Kituu; PO Ajwang; EK Ronoh

Authors

Florence G Kiburi Jomo Kenyatta University of Agriculture and Technology
Christopher L Kanali Jomo Kenyatta University of Agriculture and Technology
Gareth M Kituu Jomo Kenyatta University of Agriculture and Technology
PO Ajwang Jomo Kenyatta University of Agriculture and Technology
EK Ronoh Jomo Kenyatta University of Agriculture and Technology

Keywords:

Banana, color, firmness, vitamin C, variety, drying methods

Abstract

Products undergo several processes that result into modification of its physical, chemical and nutritional properties during drying. These modifications are mainly dependent on the drying method applied. It is vital to evaluate the effects of any drying method on product quality before adopting it for commercial application. The purpose of this study was to evaluate the effects of different drying methods on quality attributes of banana slices of four cultivars. Three drying methods (solar, biomass and solar-biomass) were used to dry fresh banana slices in a greenhouse dryer with open sun as the control. Color, firmness and vitamin C content of fresh and dried slices were measured. Regardless of the drying method, results obtained showed that the dried products were darker, firmer and had lower vitamin C content compared to that of corresponding fresh products. Resulting total color difference ranged from 7.04±0.29 to 24.27±2.52, 4.86±0.93 to 16.53±12.81, 6.02±0.02 to 21.71±2.28 and 22.06±2.44 to 39.14±7.63 for solar, biomass, solar-biomass and open sun drying, respectively. The percentage increase in firmness of banana slices after drying ranged between 151.28±56.04% to 317.50±8.92%, 98.08±14.96% to 153.19±60.54%, 91.30±61.49% to 233.33±26.07% and 125.64±36.26% to 262.50±12.62% for solar, biomass, solar-biomass and open sun drying, respectively. The reduction in vitamin C content ranged from 72.44±3.96% to 85.87±2.64%, 69.23±14.14% to 86.90±2.84%, 63.85±3.19% to 87.19±13.97%, and 62.32±4.82% to 77.14±6.38% for solar, biomass, solar-biomass, and open sun drying respectively. Among the varieties considered, Apple banana had the best color retention, highest values of firmness and highest vitamin C content before and after drying. Further, drying of banana slices in the greenhouse dryer resulted in better conservation of quality as compared to open sun drying. Generally, drying of products in the hybrid greenhouse dryer has advantages of continuous drying despite changes in weather and time as well as protecting the product from contamination.