IN Brief:
- UMass Amherst tested three filamentous fungi for submerged fermentation of pea flour.
- Aspergillus oryzae broke down 90.75% of starch while increasing measured protein yields.
- Nitrogen supplementation increased soluble protein and reduced phytic acid and trypsin inhibitor activity.
Researchers at UMass Amherst’s Department of Food Science have demonstrated that submerged fungal fermentation can substantially alter pea flour composition, increasing measured protein yield while reducing starch and several antinutritional compounds that restrict its usefulness in some food applications.
The work, presented at the American Chemical Society’s Fall 2026 meeting, compared three filamentous fungi: Neurospora crassa, Aspergillus oryzae, and Rhizopus microsporus var. oligosporus. The researchers then selected the strongest-performing organism for a second stage examining the effect of additional nitrogen.
Pea flour already provides protein, fibre, starch, and other nutrients, but its composition creates compromises for formulators. Large insoluble globulin proteins, comparatively low protein digestibility, and naturally occurring antinutritional compounds can limit performance, particularly where manufacturers want concentrated protein functionality rather than the broader nutritional profile of whole flour.
Protein processors normally address those limitations by fractionating the crop. Wet extraction can produce relatively pure concentrates and isolates but requires water, separation equipment, and downstream drying, while dry fractionation uses milling and physical separation to enrich protein with a different balance of purity, yield, and energy demand.
Fermentation changes the material instead of relying entirely on separation. Microorganisms consume or transform selected components in the flour, altering the balance between starch, protein, fibre, and other compounds while generating their own biomass and metabolites.
Among the three fungi tested, A. oryzae produced the strongest starch degradation. The ACS abstract reports that it broke down 90.75% of starch in the substrate while increasing protein yield in both the soluble and insoluble fractions, with respective figures of 39.3% and 37.8%.
The researchers attributed that performance to comparatively strong amylase activity and proteolytic efficiency. N. crassa and R. oligosporus produced more moderate substrate breakdown and retained more protein in the fungal pellet, demonstrating that organism choice affects both the composition of the fermented material and where the recoverable protein ends up.
That distribution becomes important during scale-up. A fermentation may improve overall composition but still create an awkward downstream process if the most valuable fraction is difficult to separate, wash, concentrate, or dry. The location and physical form of the protein matter almost as much as the analytical percentage.
The second stage focused on A. oryzae and examined nitrogen supplementation. Additional nitrogen significantly increased soluble protein yield and also changed ash and fat content, while concentrations of phytic acid and trypsin inhibitor activity decreased in both insoluble and soluble fractions.
Phytic acid can bind minerals and reduce their bioavailability, while trypsin inhibitors interfere with digestive enzymes involved in protein breakdown. Reducing those compounds is potentially useful, although their presence is only one part of the formulation challenge surrounding pulse ingredients.
Flavour remains another. Pea-derived ingredients can carry characteristic grassy, beany, or earthy notes that become more noticeable in lightly flavoured beverages and high-protein products. Fermentation can alter flavour chemistry, but whether the result is an improvement depends on the organism, process conditions, and final application.
Functional performance is equally important. Solubility, water holding, emulsification, foaming, gel formation, viscosity, and heat stability determine how a protein behaves during mixing, cooking, extrusion, homogenisation, or storage. Higher measured protein content alone does not guarantee that a fermented flour will outperform an established isolate on a production line.
A. oryzae does at least bring a long history of food fermentation. It is associated with traditional production of products including miso, soy sauce, and sake, giving food technologists a well-established organism to work with rather than one introduced from an unrelated industrial biotechnology application.
Submerged fermentation would still need conventional process controls at commercial scale. Fermenters require managed inoculation, temperature, oxygen transfer, agitation, pH, hygiene, and clean-in-place procedures, while unwanted microorganisms have to be prevented from competing with the production strain.
Water use is another part of the calculation. A biological process may reduce the need for some conventional fractionation stages, but submerged fermentation creates a liquid stream that must subsequently be concentrated or dried if the ingredient is to be supplied as a stable powder. Evaporating that water can become one of the largest energy loads in an ingredient plant.
The commercial case will therefore depend on the value gained from the compositional changes. If fermentation can turn relatively inexpensive pea flour into an ingredient with improved protein concentration, digestibility, flavour, and functionality without imposing excessive downstream cost, it could occupy a useful position between whole flour and heavily refined protein isolates.
Application trials are now more informative than another headline protein percentage. Meat alternatives, nutrition products, snacks, bakery formulations, and beverages impose very different requirements, and the fermented flour will need to demonstrate that its altered composition survives normal processing, storage, and sensory assessment.
The UMass results establish that fungal metabolism can remove a large proportion of pea flour’s starch and shift protein and antinutritional factors in favourable directions. Turning that laboratory improvement into an ingredient business will depend on the less fashionable parts of biotechnology — separation, drying, reproducibility, food safety, and the cost per usable kilogram leaving the factory.
