Enzyme and Antioxidant Activities of Malted Bambara Groundnut as Affected by Steeping and Sprouting Times.

Adeola Helen Adetokunboh,Victoria A Jideani,Anthony O Obilana

doi:10.3390/foods11060783

Adeola Helen Adetokunboh, Victoria A Jideani + Show 1 more

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https://doi.org/10.3390/foods11060783

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Abstract

Bambara groundnut (BGN) is termed a complete food due to its nutritional composition and has been researched often for its nutritional constituents. Malting BGN seeds have shown improved nutritional and functional characteristics, which can be used to produce an amylase-rich product as a functional ingredient for food and beverage production in homes and industries. The aim of this study was to investigate the enzyme and antioxidant activities of malted BGN affected by steeping and sprouting times. BGN was malted by steeping in distilled water at 25–30 °C for 36 and 48 h and then sprouted for 144 h at 30 °C. Samples were drawn every 24 h for drying to study the effect of steeping and sprouting times on the moisture, sprout length, pH, colour, protein content, amylase, total polyphenols, and antioxidant activities of the BGN seeds. The steeping and sprouting times significantly affected the BGN malt colour quality and pH. The protein content of the malted BGN seeds was not significantly different based on steeping and sprouting times. Steeping and sprouting times significantly affected the α- and β-amylase activities of the BGN seeds. The activity of amylases for 36 and 48 h steeping times were 0.16 and 0.15 CU/g for α-amylase and were 0.22 and 0.23 BU/g for β-amylase, respectively. Amylase-rich BGN malt was produced by steeping for 36 h and sprouting for 96 h. Amylase-rich BGN malt can be useful as a functional food ingredient in food and beverage formulations.

Highlights

The chemicals and reagents were of analytical standards. α- and β-amylase kits were from Megazyme Ltd., Ireland
The increase in total polyphenolic contents in this study during steeping and sprouting times showed that Bambara groundnut (BGN) malt is an antioxidant-rich product and was improved with steeping and sprouting time, and this could, be beneficial for consumers with oxidative stress-associated diseases [191,192]. These findings indicated that an increase in total polyphenols of sprouted BGN has the potential for use in the nutraceutical industry to offer some health benefits to consumers
The result of the antioxidant activities using ferric reducing antioxidant power (FRAP) and Diphenyl-1-Picrylhydrazyl Assay (DPPH) assays in this study indicated that steeping and sprouting times increased antioxidant activities in BGN seeds

Summary

Introduction

Malting is the incomplete germination of cereal grains and pulses under controlled water, temperature, and humidity [1–5]. It involves three stages: steeping, sprouting, and drying (kilning), carefully monitored because every process stage affects the end product [4,6]. Sprouting and acrospires form during the malting process, and enzymes become active, altering the grain structure, and resulting in a malt product used in the brewing, food, and beverage industries. The sequence of substantial changes in metabolites and enzyme activities in the resultant malts, on the other hand, is time-dependent [4,8,9]. The enzymes released catalyse the breakdown of cell wall reserves (polysaccharides and starchy energy) necessary for sprouting and malt production [10–12]

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