New food ingredient via acid-tolerant Rhizopus oligosporus growth

•Compared solid-state and submerged fermentation, optimizing both for biomass yield.•Rhizopus oligosporus biomass optimized at pH below 4, ensuring high yield and safety.•High protein yield from acid-tolerant biomass, rich in essential amino acids.•Optimized biomass with good emulsification, water absorption, and oil retention properties.•Biomass emulsifies, absorbs water, retains oil, but lacks foaming and gelation properties. As the global population grows, the consumption of unsustainably produced proteins increases. Researching sustainable food sources with a positive environmental impact is essential. This research provides valuable insights into the production and application of nutrient rich food sources. The potential of the biomass generated through fermentation with Rhizophus oligosporus was evaluated as a new protein source with low environmental impact. A fermentation method has been optimized to maximize the biomass production of R. oligosporus mycelium in solid-state and submerged-state fermentation, yielding 5.9 g dry weight/L and 5.0 g dry weight/L, respectively. The growth medium for these fungi was adapted to acid-tolerant (pH 4 and 3) conditions to create a food development environment that is more difficult for pathogens to thrive in, both in solid state and submerged state fermentation. The highest protein content obtained was 38.4 % wet weight by solid state fermentation. Fungal biomass exhibited techno-functional properties relevant to food product development tested both on pH 4 and pH 3, showing high water absorption and emulsifying activity, particularly in submerged fermentation at pH 3. In contrast, solid-state fermentation at pH 4 resulted in higher emulsion stability. This research demonstrates the potential of R. oligosporus as an acid-tolerant, high-quality protein ingredient with valuable functional properties. Its efficient production using minimal resources makes it a valuable asset for the food industry. [Display omitted]