Evaluating the potential of Bacillus subtilis fermented okara as a functional food ingredient through in vitro digestion and fermentation

ABSTRACT

In this study, in vitro digestion and fermentation was employed to simulate the consumption of fermented okara and hence, evaluate its potential as a functional food ingredient. This is to develop a method of utilizing okara without producing secondary waste. Fermentation increased the amount of soluble dietary fiber by 187%. Bioaccessibility of amino acids, fatty acids, and vitamin K2 MK-7 is higher in the digestion supernatant of fermented okara. Bacillus subtilis also remained viable after digestion. Supernatants of fermented okara exhibited higher bio accessibility of total phenolic content and higher DPPH radical scavenging activity in the small and large intestines. Similarly, the concentrations of acetic acid, propionic acid, and butyric acid were 44.4%, 46.9%, and 51.8% higher, respectively. The gut microbiota was also found to be different in the fermentation supernatants between fermented and unfermented okara. Results demonstrated the potential of fermented okara as a functional food ingredient.

KEYWORDS:

• In vitro digestion and fermentation
• okara fermentation
• Bacillus subtilis
• gut microbiota
• bio accessibility

Acknowledgments

We would like to thank Vitasoy International Singapore Pte Ltd for providing okara and NovogeneAIT, Singapore for the expertise in 16s rRNA sequencing.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethics approval

The research protocol was approved by the Nanyang Technological University Review Board as the IRB reference number IRB-2019-10-048. Informed consent was obtained from all individual participants included in the study.

Additional information

Funding

The funding for this research was supported by the School of Chemical and Biomedical Engineering (SCBE) at Nanyang Technological University (NTU).