Effect of Harvesting Time, Drying Method and Packaging of Cowpea Leaves on Microbial Contamination

Abstract

After harvesting, cowpea leaves have high moisture content which exposes them to microbial growth. Drying is used to reduce the moisture and extend the shelf life. However, dried foods are susceptible to spoilage resulting from many microbial, biological, chemicals and physical reactions. After drying packaging materials used by farmers also expose the dried product to a range of microorganisms due to their different moisture retention capacity. This study aimed at prolonging the keeping quality of the dried cowpea leaves for use during off- season and coming up with information on the best and affordable packaging material that would ensure safety of dried leaves. Data was collected on fungal, bacteria and coliforms. The data was subjected to variance using Statistical Analysis System 9.2 edition and significantly different means separated using LSD at 5%. The combination of harvesting stage, drying method and packaging material significantly (p<0.05) influenced microbial load (bacterial and fungal), however no coliforms were observed. Open sun-dried cowpea leaves at 21 DAS, packaged in woven and aluminium foil reported a high number of bacterial and fungal counts compared to the kraft packaging. Oven dried cowpea leaves, harvested at 49 days after sowing (DAS), and in kraft paper resulted in the least bacterial and fungal contamination compared to those packaged in woven and aluminium foil. Sun drying and harvesting time after at 21, 35 and 49 DAS contained the highest bacterial and fungal contamination followed by solar drying and the least was recorded in oven drying method. This research shows that correct harvest stage, adoption of oven and solar drying methods and use of correct packaging material will prolong the shelf life of dried cowpea leaves therefore enhancing food security and food safety.