Fermentation unlocks antidiabetic, antioxidant power in common pulses, University of Illinois Urbana-Champaign study finds

A new study from the University of Illinois Urbana-Champaign has found that fermenting common legume pulses – such as red lentils, green split peas, and black beans – under carefully optimized conditions can significantly enhance their antidiabetic and antioxidant properties. The findings could help pave the way for developing more functional, plant-based food products aimed at preventing chronic illnesses like Type 2 diabetes.

Led by food science professor Elvira Gonzalez de Mejia and graduate student Andrea Jimena Valdés-Alvarado, the research team used the probiotic bacterium Lactiplantibacillus plantarum 299v (Lp299v) to ferment pulse flours made from black beans, black-eyed peas, green split peas, red lentils, and pinto beans. The results, published in the journal Antioxidants, showed dramatic increases in antioxidant activity – by as much as 83% – and improvements of up to 70% in markers related to Type 2 diabetes regulation.

“Red lentil and green split pea exhibited the greatest improvements in antioxidant scavenging activity and protein solubility,” said de Mejia. “And they showed the greatest modulation of two enzymes that improve insulin metabolism.”

The fermentation process also enhanced the solubility of proteins in the pulses – particularly in red lentils and green split peas – making them more digestible and potentially more effective as functional food ingredients. However, not all pulses responded the same way. Soluble protein content declined in fermented black beans and pinto beans, underscoring how fermentation outcomes can vary widely depending on processing conditions.

Valdés-Alvarado noted that Lp299v, the bacterium used in the study, not only supports gut health but also continues to provide benefits after consumption. “It will not only preserve the fermented product that you’re consuming, it will also produce these peptides or amino acids that are more easily absorbed than the intact protein in the pulses,” she said.

To identify the most effective fermentation parameters, the team tested different concentrations of pulse flour (3% and 9%), fermentation durations (8, 16, or 24 hours), and levels of α-amylase, an enzyme that breaks down starch to supply fermentable sugars for bacterial growth. Using statistical optimization methods, they found the best combinations to maximize antioxidant activity, protein solubility, and glucose-regulating effects.

The findings are especially relevant as demand for plant-based protein continues to rise globally. “Up to 70% of the protein demands of the global population are met by plant-based foods,” said de Mejia. “Products like legumes, pulses and cereals are gaining increasing attention as an alternative for animal-based proteins.”

Among the most promising findings was the impact on blood sugar regulation. Fermentation significantly suppressed the activity of two enzymes involved in glucose metabolism. The first, dipeptidyl peptidase-IV, which breaks down hormones that regulate blood sugar, was inhibited by 40% to 70%. The second, α-glucosidase, which helps digest complex carbohydrates, was inhibited by 30% to 60%.

“These findings are important and have the potential for informing continued work on fermentation and strategies for improving the functional properties of health-promoting foods,” de Mejia said.

Valdés-Alvarado shared some of the initial findings at the American Chemical Society’s conference in San Diego in April, and she will present the full results at the Institute of Food Technologists’ annual meeting in Chicago in July.

The broader implications extend beyond individual health. With the USDA encouraging Americans to consume more legumes – including beans, peas, chickpeas, and lentils – as part of its 2020-2025 Dietary Guidelines, studies like this help validate the nutritional and functional benefits of those recommendations. “We need to find adequate processing conditions and motivate the food industry to use them in dairy beverages or meat substitutes,” de Mejia said.

In addition to promoting health, fermented pulses may offer a sustainable way to address global challenges such as food insecurity, resource scarcity, and climate change. Legume crops, which enrich soil and require less water and fertilizer than many other protein sources, could offer economic and environmental benefits for agricultural producers in Illinois and beyond.

Dave Luthria, a research chemist with the USDA, supplied the raw pulse samples used in the study. The project was supported by funding from the USDA’s Agricultural Research Service under the Pulse Crop Health Initiative.