Effects of Rhizopus oligosporus-Mediated Solid-State Fermentation on the Protein Profile and α-Glucosidase Inhibitory Activity of Selenium-Biofortified Soybean Tempeh

Summary

Researchers used a fungus called Rhizopus oligosporus to make selenium-enriched tempeh, a traditional soybean food. The selenium-enriched tempeh had better protein breakdown, higher amino acid levels, and was better at controlling blood sugar than regular tempeh. This research suggests that selenium-biofortified tempeh could be a healthy functional food for people looking to manage blood sugar levels naturally.

Background

Selenium is an essential trace element required for human health, with deficiency affecting approximately 1 billion people worldwide. Solid-state fermentation using Rhizopus oligosporus offers a promising strategy for enhancing nutritional quality of legumes while biotransforming inorganic selenium into bioavailable organic forms.

Objective

This study evaluated Rhizopus oligosporus-mediated solid-state fermentation for selenium biofortification in soybean tempeh, assessing the effects of selenate and selenite supplementation on fungal growth, protein profiles, amino acid composition, selenium speciation, and α-glucosidase inhibitory activity.

Results

Selenate at 42 mg/kg significantly increased flavor amino acids, essential amino acids, and total amino acids in tempeh. Selenite favored organic selenium conversion (84.1%), producing mainly selenomethionine and selenocystine. Se-enriched tempeh demonstrated potent α-glucosidase inhibition with IC50 values of 1.66-2.89 mg/mL, significantly lower than Se-free tempeh (3.26 mg/mL).

Conclusion

Selenium fortification via Rhizopus oligosporus fermentation significantly enhances tempeh’s nutritional profile and bioactivity. Selenate more effectively promotes amino acid accumulation while selenite favors organic selenium conversion. Se-biofortified soybean tempeh represents a promising functional food with blood-sugar-friendly properties.
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