Assessment of Changes in Beta-carotene Content and Sensory Attributes of Two Sweet Potato Varieties as Influenced by Organic and Inorganic Fertilizers and Storage Methods
Two field experiments were conducted at two seasons at the research fields of the University of Education, Winneba-Mampong campus from September, 2011 to January, 2012 and April to July, 2012 to assess changes in beta-carotene content and sensory attributes of two sweet potato varieties (Okumkom and Apomuden) grown under organic and inorganic fertilizers and three different storage methods in Ghana. Cooked samples of the harvested sweet potato roots were evaluated for their sensory attributes. In the storability studies, the harvested roots were sorted, cured and stored under three storage methods for 3 months. The beta- carotene changes in the stored roots were assessed. There was a significant difference (p<0.05) between Apomuden and Okumkom grown under amendment and the control in beta-carotene content at harvest and in pit store in both seasons. The beta- carotene content of Apomuden increased by 15-30% in pit store during the minor season than at harvest. Both varieties grown under amendment and the control and stored in pit was the most effective storage method in terms of beta-carotene over ash and grass storage in both seasons. There was a significant difference (p<0.05) between Okumkom and Apomuden in root texture and palatability at harvest and after cooking during the minor season. Apomuden differed significantly (p<0.05) from Okumkom in root colour and flavour at harvest and after cooking during the major season. The application of 30-45-45 kg/ha NPK to both varieties was more acceptable with regard to root taste, colour and palatability than the other treatments during the minor season. For high beta-carotene content of sweet potato, farmers should grow Apomuden in both seasons than Okumkom. Farmers should store sweet potato roots in pit than in ash or grass after harvest for high beta-carotene content in both growing seasons. Farmers are to grow sweet potato on amended plots, especially on15-30-30 kg/ha NPK +5t/ha CM and 10t/ha CM plots during the minor season and on 30-45-45 kg/ha NPK plot during the major season for high beta-carotene content. Farmers should grow sweet potato, especially Okumkom on 30-45-45 kg/ha NPK plot for fibrous texture, palatable and overall acceptable roots during the minor season. Farmers should grow Apomuden during the major season for high root colour, flavour and overall acceptable roots. This suggests the need to modify the nutrient supply according to environmental conditions. Knowledge of these changes can facilitate the estimation of growth period, modification of nutrient supply in relation to environmental conditions, storage condition and time for different sweet potato varieties in order to meet different food industry needs.
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