Effect of storage on the physico-chemical characteristics and acceptability of fresh cassava (manihot esculenta crantz) roots
Cassava roots are highly perishable and some varieties can start showing symptoms of deterioration within 24 hours after harvest. Due to this short "green life", it is therefore difficult to maintain the quality of fresh cassava to await transportation, preparation for consumption or even processing to acceptable products. This study was designed to assess the shelf life of freshly harvested cassava at room temperature and under refrigeration temperature. The physical-chemical characteristics and acceptability of fresh cassava (Manihot esculenta crantz) was determined after storage. Three popular cassava varieties (Muchericheri, Ex-Ndolo and KME 1) were obtained from KARl research station in Embu and transported within 2 hours to the laboratories of the Department of Food Science, Nutrition and Technology within hours. Each variety of a total of 210 roots was divided into four batches and a batch from each was stored at room temperature (23 ± 3°C), 2°C, 4°C and 6°C. Each batch in storage was analyzed initially and thereafter after every 3 days for dry matter, visible browning, invisible browning, total sugars, texture, visual discolouration and sensory acceptability. Data was analyzed using SAS version 6.0 and means separated using the Duncan Multiple test range. All cassava varieties stored at room temperature retained freshness for two days only. During storage at 2°C, 4°C and 6°C, the cassava varieties manifested different shelf lives depending on the variety. Muchericheri stored for 6 days at 2°C, for 9 days at 4°C and 6 days at 6°C. Ex-Ndolo stored for 12 days at 2°C, for 6 days at 4°C and 6 days at 6°C. Finally KME 1 stored for 9 days at 2°C, for 6 days at 4°C and 9 days at 6°C. Contrary to expectations, not all varieties stored best at 2°C. Muchericheri stored best at 4°C and KME 1 stored equally well at 2°C and 6°C. Only Ex-Ndolo stored best at 2°C. Results showed that fresh cassava can be stored at ambient temperature for a maximum of 2 days, at 2°C for a maximum of 12 days, at 4°C for a maximum of 9 days and at 6°C for a maximum of 9 days without significantly losing its eating quality. The study concluded that retention of freshness by cassava during storage depended on variety and temperature of storage.