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Research article2025Peer reviewedOpen access

Impact of fermentation time on the in vitro enzymatic digestibility of traditionally extracted pearl millet (Pennisetum glaucum) starch

Hamid, Manhal Gobara; Elkhatim, Khitma A. Sir; Idris, Yousif M. A.; Elsafy, Mohammed; Rahmatov, Mahbubjon; Abdelhalim, Tilal; Muneer, Faraz

Abstract

In this study, we used a traditional Sudanese fermentation method to extract starch from pearl millet (Pennisetum glaucum L.) varieties and investigated the impact of fermentation time (1 and 7 days) on in vitro starch digestibility. From fermented grains two distinct layers of starch were obtained i.e. the upper layer (Jir Khadim), and the lower layer (Jir Hur). The in vitro digestibility analysis of all the starch samples showed that both starch layers exhibited rapid hydrolysis rates within the first 60 min of enzymatic digestion, although the 7-day fermented starches exhibited significantly higher hydrolysis rates after 120 min than 1-day fermented samples. Scanning electron microscopy have shown that the longer fermentation time impacted starch granule morphology with surface perforations, indentations, and granule degradation that might have contributed to higher starch digestibility. Pearl millet varieties with higher amylose content i.e. Ashana and Bioda, showed slower hydrolysis rates, higher resistant starch (RS) levels, and reduced readily digestible starch (RDS). These findings demonstrate that fermentation time significantly affects starch digestibility and fraction distribution, with amylose content and fermentation-induced structural modifications playing key roles. This study underlines the potential for standardizing indigenous food-processing methods for developing modern food products with tailored digestibility profiles.

Keywords

Starch isolation; Hydrolysis rate; Starch morphology; Free glucose; Total starch

Published in

Food Science and Technology
2025, volume: 218, article number: 117523

SLU Authors

UKÄ Subject classification

Food Biotechnology

Publication identifier

  • DOI: https://doi.org/10.1016/j.lwt.2025.117523

Permanent link to this page (URI)

https://res.slu.se/id/publ/140889