Effect of traditional processing methods on the β-carotene, ascorbic acid and trypsin inhibitor content of orange-fleshed sweet potato for production of amala in Nigeria.

BACKGROUND

The aim of the work was to study the effect of traditional processing methods on the β-carotene, ascorbic acid and trypsin inhibitor contents of orange-fleshed sweet potato amala. The most common sweet potato in Nigeria is white or yellow fleshed, which is very low in provitamin A. However, efforts are underway to promote orange-fleshed sweet potato to improve provitamin A intake. This paper describes how orange-fleshed sweet potato slices were traditionally processed into amala, which is increasingly consumed in Nigeria.

RESULTS

The study revealed that both the cold and hot fermentation methods resulted in increased vitamin A levels and lower vitamin C levels in orange-fleshed sweet potato. Further processing to make amala resulted in a fall in both vitamin A and C content. The study found an increase in trypsin inhibitor activity following the cold-water fermentation and a decrease following the hot-water fermentation compared to raw orange-fleshed sweet potato. Trypsin inhibitor activity in amala produced using both the cold and hot methods was below detectable levels.

CONCLUSIONS

The results indicate that amala produced from traditionally fermented orange-fleshed sweet potato could be a good source of vitamins A and C for the rural poor and that the processing removes any potential negative effects of trypsin inhibitors. © 2015 Society of Chemical Industry.