Agronomic performance, consumer acceptability and nutrient content of new sweet potato varieties in South Africa

[摘要] English: Malnutrition, including vitamin A deficiency, and food insecurity are national priorities in South Africa. Sweet potato has several agronomic advantages giving it potential to address both priorities. The crop is popular amongst resource-poor farmers as it is easy-to-grow and hardy. Orange-fleshed genotypes (β-carotene-rich) are used internationally in crop-based approaches to address vitamin A deficiency. Due to a shortage of varieties with desirable traits for resourcepoor farmers, several new varieties have been developed. The overall objective of this study was to evaluate the agronomic performance, sensory quality and nutrient content of new South African varieties. The ANOVA of new varieties in MET, indicated significant differences in dry matter content, marketable yield, number of marketable roots and total yield. AMMI and GGE biplot analysis showed that cream-fleshed varieties Ndou and Lethlabula produced yields comparable to the commercial variety Blesbok. Ndou (unstable high yield), Mokone and Monate (stable, average yields) and Amasi (moderately unstable, average yield) had dry matter content similar to the control variety Mafutha (known for sweet and dry taste). Recommending these new varieties will have a considerable yield advantage over Mafutha, with a possible impact on food security. From MET with nine orange-fleshed varieties the ANOVA and GGE SREG analysis indicated that Impilo produced stable, high yield and 2001-5-2 unstable, high yield. Both had average dry matter content. The two varieties offer a significant yield advantage above USA imports, previously recommended to address vitamin A deficiency. Orange-fleshed varieties produced significantly lower yield than cream-fleshed ones. Raw roots of nine orange-fleshed varieties, harvested from MET at four agro-geographical production sites, had an overall mean trans-β-carotene content of 5091 to 16456 μg/100 g. Resisto, Khano, 2001-5-2, W-119, Beauregard and 1999-1-7 exceeded 5500 μg/100 g β-carotene (breeding target). Dry matter content ranged from 23.1% (Impilo) to 28.7% (W-119). The content of six minerals was determined. Consumption of a boiled portion of 100 g raw root of all nine varieties can potentially contribute to �?00% of the recommended intake for vitamin A, 21% of magnesium, 12% of zinc and 9% of iron for 4 to 8 year old children. CIE L* and a* color measurement of nine varieties with varying orange flesh color had the best correlations with total β-carotene content, and is a faster selection method. A mathematical function with natural logarithm (ln) transformation derived to predict total β-carotene content from color L*, predicted 91% of the values with >75% accuracy. The color and taste acceptability of boiled sweet potato of new varieties were evaluated in two experiments by grade 1 �?7 learners and adults in a BIBD using a 5-point hedonic scale. A trained panel found clear differences in the sensory attributes of the varieties. Cream to yelloworange varieties, Mafutha, Lethlabula and Phala had the highest consumer panel (n=190) scores, associated most with wateriness, discolor, graininess, gumminess, sweet potato-like flavor and instronforce. Orange-fleshed varieties Impilo, Excel, Resisto, 2001-5-2, Serolane and W-119, and cream-fleshed varieties Monate and Ndou were acceptable to the second consumer panel (n=216), mostly related to dry matter content, maltose content, sweet flavor, wateriness, discoloration and dark edges. High maltose and starch content were found in Ndou, Serolane, Resisto and Monate; while Blesbok, Impilo and 2001-5-2 had high fructose and glucose content. Orange-fleshed varieties were as acceptable as cream-fleshed varieties. The present study provides novel results on G x E analysis, comprehensive and systematic determination of nutrient content, consumer and sensory assessment of a considerable number of new cream to orange-flesh sweet potato varieties promoted in South Africa. Varieties Ndou, Mokone, Monate and Amasi were recommended to address food security; and Impilo and 2001- 5-2 to address vitamin A deficiency.

[发布机构] University of the Free State