Study on Post-harvest Proximate Composition and Water Activity of Three Cultivars of Frafra Potatoes (Solenostemon rotundifolius [Poir.]) from Upper East Region, Ghana

Solenostemon rotundifolius (frafra potato) is an important food security crop in areas where it is cultivated in Ghana. However, the crop suffers research neglect in Ghana. More research on the crop is therefore needed for the crop to experience any form of meaningful improvement and utilisation beyond the area of its cultivation in Ghana. This present experiment therefore aimed to study the post-harvest proximate composition and water activity of three cultivars (black, white and brown cultivars) of frafra potatoes (Solenostemon rotundifolius) from the Upper East Region of Ghana. The white cultivar recorded the highest water activity value of 0.72 whiles the black and brown cultivar both recorded a lower water activity value of 0.68. The white cultivar recorded the highest moisture content of 7.20% whiles the brown and black cultivars recorded moisture content of 7.00% and 6.60% respectively. The brown cultivar recorded the highest protein content of 5.25 %, followed by 4.81% for the black cultivar and 4.38% for the white cultivar. Considering the ash content, the brown cultivar recorded a higher value of 4.00% followed by 3.80% recorded by the white cultivar and least value of 3.20% recorded by the black cultivar. The white cultivar recorded the highest fat content of 1.00% whiles the brown and black cultivar both recorded the lowest fat content of 0.20%. The black and brown cultivars both recorded the same higher fibre content of 1.00% followed by the lowest fibre content of 0.20% by the white cultivar. The black cultivar recorded the highest Nitrogen free extract (NFE) content (84.19%) followed by that of the white cultivar (83.42%) with the least being that recorded by the brown cultivar (82.55%). In all, mean water activity, moisture, protein, ash, fat, fibre and NFE values for the three cultivars were 0.69±0.02, 6.93±0.31%, 4.81±0.44%, 3.67±0.42%, 0.47±0.46%, 0.73±0.46% and 83.39±0.82% respectively. The mean moisture content and water activity recorded in this study indicate that processing frafra potatoes into flour will extend its post-harvest shelf life. Based on the moisture content and water activity values reported in this present study, the black cultivar of frafra potatoes will have the longest postharvest shelf life followed by the brown and white cultivars when processed into flour.