Issue 6, 2023

Bioconversion of spent coffee grounds to prebiotic mannooligosaccharides – an example of biocatalysis in biorefinery

Abstract

Spent coffee ground (SCG), an agro-industrial waste, have a high content of polysaccharides such as mannan, making it ideal for utilisation for the production of nutraceutical oligosaccharides. Recently, there has been growing interest in the production of mannooligosaccharides (MOS) for health promotion in humans and animals. MOS are reported to exhibit various bioactive properties, including prebiotic and antioxidant activity. In this study, SCG was Vivinal pretreated using NaOH, characterized and hydrolysed using a Bacillus sp. derived endo-β-1,4-mannanase, Man26A, for MOS production. Structural analyses using Fourier-transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) were conducted to assess the efficacy of the pretreatment. Lignin removal by the pretreatment from SCG was clearly shown by TGA. FT-IR, on the other hand, showed the presence of α-linked D-galactopyranoside (812 cm−1) and β-linked D-mannopyranoside residues (817 cm−1) in both SCG samples, signifying the presence of mannan. Hydrolysis of pretreated SCG by Man26A produced mannobiose and mannotriose as the main MOS products. The effect of simulated gastric conditions on the MOS was investigated and showed this product to be suitable for oral administration. Finally, the prebiotic effect of the MOS on the growth of selected beneficial bacteria was investigated in vitro; showing that it enhanced Lactobacillus bulgaricus, Bacillus subtilis and Streptococcus thermophilus growth. These findings suggest that SCG is a viable source for the production of MOS which can be orally administered as prebiotics for effecting luxuriant growth of probiotic bacteria in the host's digestive tract, leading to a good health status.

Graphical abstract: Bioconversion of spent coffee grounds to prebiotic mannooligosaccharides – an example of biocatalysis in biorefinery

Article information

Article type
Paper
Submitted
29 Nov 2022
Accepted
13 Jan 2023
First published
26 Jan 2023
This article is Open Access
Creative Commons BY license

RSC Adv., 2023,13, 3773-3780

Bioconversion of spent coffee grounds to prebiotic mannooligosaccharides – an example of biocatalysis in biorefinery

M. Magengelele, S. Malgas and B. I. Pletschke, RSC Adv., 2023, 13, 3773 DOI: 10.1039/D2RA07605E

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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