The by-products of coffee processing may have “potential for fermentation biotechnology and the development of next-generation probiotic or postbiotic products,” wrote researchers from Ecuador and Romania in Frontiers in Microbiology.
The new study adds to the growing interest in non-conventional yeasts, spurred by advances in biotechnology. Researchers are tapping into novel strains to develop functional ingredients that offer clean-label plant-based alternatives to synthetic formulations or animal-based products.
Non-conventional yeasts
The global specialty yeast market is experiencing steady financial growth, valued at USD 6.11 billion in 2025 and projected to maintain a compound annual growth rate (CAGR) of 5.95%, reaching USD 10.24 billion by 2034.
Non-conventional yeasts (NCYs) are the term given to yeasts other than Saccharomyces cerevisiae - bakers’ or brewers’ yeast that is the dominant yeast used in global industry.
NCYs have unique metabolic pathways, a broad substrate range, and high tolerance to industrial conditions.
Their industrial applications include bioplastics, biofuels, biopharmaceuticals, food additives, protein production, specialized brewing, plant-based supplements such as omega-3, and gut health products.
A key NCY strain, Yarrowia lipolytica, originates from marine environments, oil-contaminated soil, and meat and dairy products. However, it has also been isolated from cold-pressed olive oil and found to have probiotic properties that could be utilized in the development of vegan foods.
Despite its potential, Y. lipolytica has faced production challenges due to its dimorphic nature, where it can morph into a filamentous hyphae form, which is undesirable in liquid fermentations.
NCYs evolve naturally on the surfaces of fruits such as grapes, apples, and plums. They can add diverse flavors and aromas that can be utilized in industries such as winemaking.
Coffee cherry is the small, round fruit that grows on the coffee plant, whose seeds are harvested to make coffee beans. The remaining dried outer skins and pulp were traditionally treated as waste but are now upcycled into food ingredients such as cascara tea.
The current researchers sought to characterize the functional properties of NCYs isolated from coffee cherry fermentations to establish their potential as a novel ingredient in next-generation probiotic or postbiotic development.
Study details
The researchers obtained yeast isolates from fermented coffee cherries from three Coffea arabica varieties.
They identified five NCY isolates (four Kurtzmaniella quercitrusa isolates and one Meyerozyma caribbica) using DNA extraction.
Saccharomyces strains were used to compare tolerance to simulated gastric conditions. The researchers also evaluated other properties, including resistance to physiological stress, antimicrobial activity, and susceptibility to antifungal agents.
They observed that all the isolates “exhibited strain-dependent tolerance to simulated gastrointestinal and environmental stresses”.
The NCYs also exhibited strain-dependent effects on epithelial scratch closure, which the scientists noted were comparable to those of the probiotic yeast S. boulardii, warranting further investigation into their postbiotic and probiotic potential.
They wrote: Coffee cherry-derived NCYs exhibited strain-dependent probiotic-associated traits, favorable preliminary biosafety profiles, antimicrobial activity, and high cytocompatibility, supporting their potential for fermentation biotechnology and the development of next-generation probiotic or postbiotic products.”
Future studies including human validation are necessary to confirm the safety and efficacy of the isolates.
Source: Frontiers in Microbiology, https://doi.org/10.3389/fmicb.2026.1920410, “Functional assessment of coffee cherry-derived non-conventional yeasts identifies promising candidates for probiotic and postbiotic applications.” Authors: V. Cifuentes et al.
