Effects of Bioprocessing and Ultrasonication on Nutritional, Functional and Antioxidant Properties of African Yam Bean Flour and Cookie Quality

Abstract

This study investigated the effects of bioprocessing (fermentation, germination, combined germination and fermentation and combined germination and solid-state fermentation) and ultrasonication (US) treated at 15 and 30 min (US 15 and US 30) on African yam bean (AYB) flour properties. Changes in nutritional, mineral, functional, antinutritional and antioxidant properties were evaluated, along with the consumer acceptability of cookies made from the processed flours. The moisture content of all the bioprocessed samples was higher, except for the ultrasonicated samples, which showed a decrease. The crude protein of the fermented AYB (FAYB) and US 15 exhibited higher values, with a decrease in germinated and combined germinated samples. The FAYB showed a significant increase in potassium and phosphorus, while the US 30 sample showed an increase in phosphorus and magnesium. There was a decrease in foaming capacity, bulk density, water absorption capacity and antinutritional factors (tannin and alkaloid), with an increase in total flavonoid, total phenolic and antioxidant activities of all the processed AYB flours. The ultrasonication treatments demonstrated a higher FRAP (ferric reducing ability of plasma). A consumer acceptability test revealed that the cookies made from US 15 flour were most preferred for taste, appearance, crispiness, texture, colour and overall acceptability, while the combined germinated solid-state fermented samples ranked highest for aroma. These findings suggest that ultrasonication, in particular, has a promising potential for enhancing AYB utilisation in food product development.