Abstract:
Prebiotics are non-digestible food components that promote the growth and health of beneficial
bacteria in the gut. This has the potential to increase the host’s health. Inulin is a widely studied
prebiotic, but interest is growing in alternative plant-based sources. The objective of this study
was to investigate and comparatively evaluate the prebiotic potential of yellow sweet potato
flour, jackfruit bulb flour, banana pseudo-stem core flour, and sugarcane residue flour, using inulin
as a reference, to identify new, sustainable sources of prebiotics. The prebiotic potential was
determined by analysing the crude fibre content of the flours and performing fermentation experiments
with Lactobacillus rhamnosus cultured in MRS (DeMan, Rogosa, and Sharpe) broth.
Optical density (OD) readings were taken to monitor microbial growth at 0, 4, 6, and 24 hours
after inoculation. The yellow sweet potato flour exhibited the highest prebiotic activity with
an OD value of 0.83±0.02 Abs (10−1 dilution) after 24 hours post-inoculation, suggesting that
yellow sweet potato flour has high potential as a source of prebiotics. According to the optical
density measurements, banana pseudo-stem core flour observed microbial growth in the early
stage of fermentation. The microbial growth in the banana pseudo-stem core flour stabilised by
24 hours, indicating that banana pseudo-stem core flour could be beneficial for short-term promotion
of gut health. Sugarcane residue flour, which has a high crude fibre content (25.83%),
displayed slower but sustained microbial growth that could be attributed to its increased fibre
content, which takes a longer time for microbial digestion. Jackfruit bulb flour displayed moderate
prebiotic activity, corresponding with its lower crude fibre content. These flours were
also analysed using Fourier Transform Infrared Spectroscopy (FTIR), which revealed broad hydroxyl
and glycosidic bond peaks indicating fermentable carbohydrates, together with carbonyl,
protein, lipid, and lignin signals, confirming the complex bioactive composition and prebiotic
potential of the flours. The data were statistically analysed, indicating that the flours and fermentation
times were significantly different, with the results showing the superior performance
of yellow sweet potato and banana pseudo-stem core flours. The findings suggest that these
alternative flours could serve as prebiotic sources, supporting dietary diversity and gut health.
