Performance of different storage systems on physico-chemical quality of ware potato in Elgeyo Marakwet County, Kenya

Abstract

Potato (Solanum tuberosum L.) is an important food security crop and substitute for cereal crops, considering its potential high yield and nutritive value. However, constant availability of good quality produce is hampered by postharvest losses resulting from inadequate storage and inappropriate choice of potato varieties for processing. Moreover, suitability of common storage systems on quality of raw and processed potato has not been fully elucidated. This study aimed at comparing the performance of three stores (ambient charcoal-cooled store, traditional grass thatched hut and diffused light store {DLS}) on physico-chemical quality of four potato varieties (Shangi, Destiny, Markies and Dutch Robjin) in Elgeyo Marakwet County, Kenya. Triplicate bags of 4.5 Kg of potatoes were stored for 8 weeks. Physical parameters (weight loss, sprouting, greening, rotting and shrinkage) were assessed weekly, while chemical parameters (reducing sugars, starch and proteins) in raw and processed (chips and crisps) potatoes were assessed at 0, 4 and 8 weeks. Store temperature and relative humidity were recorded daily. Storage performance varied depending on potato variety and store type. By week 8, higher temperature and lower relative humidity in DLS contributed to high mean (19.74±0.94 – 34.14±2.14%) potato weight loss, greening and shrinkage. Mean sprouting was significantly lower (P<0.05) in Dutch Robjin than all potato varieties. Also, starch content in raw Shangi (10.02±0.03 – 13.02±0.01%) in all stores was significantly higher (P<0.05) when compared to Destiny (4.12±0.11 – 6.22±0.09) or Dutch Robjin (5.80±0.13 – 7.56±0.01), while mean reducing sugar content in raw potatoes stored in hut and charcoal stores was significantly lower (P<0.05) than the DLS. Protein content in processed potatoes was significantly higher (P<0.05) than in raw potatoes. Low reducing sugar levels are desirable for processing. Charcoal and hut stores gave desired physical characteristics with low levels of reducing sugars, hence recommended for storage of ware potato.