Non-Conventional Yeasts for Lipase Production from Agro-Industrial Residues Under Solid-State Fermentation: A Scoping Review

Non-conventional yeasts (NCYs) are promising microbial platforms for converting agro-industrial residues into value-added enzymes, yet their use for lipase production under solid-state fermentation (SSF) remains fragmented across the literature. This scoping review systematically mapped studies on lipase production by NCYs using agro-industrial residues under SSF. Scopus and Web of Science Core Collection were searched according to a PRISMA-ScR-based protocol, yielding 38 eligible original studies published between 1993 and 2025. Yarrowia lipolytica dominated the evidence base, accounting for 21 studies (55.3%), followed by Candida rugosa with six studies. Oilseed- and vegetable-oil-processing residues were used in 31 studies (81.6%), while cereal brans and fruit-processing by-products were also common substrates. Considerable variation was observed in substrate formulation, moisture, supplementation, fermentation time, optimization strategy, enzyme recovery, lipase assays, and activity units. This methodological heterogeneity precluded meaningful meta-analysis and limited direct comparison of reported lipase activities. Although several studies demonstrated applications in ester synthesis, lipid modification, polymer degradation, detergents, and wastewater treatment, most processes remained at the laboratory scale. Future development should prioritize standardized activity reporting, broader NCY diversity, improved reactor-scale control, and integrated downstream strategies to advance SSF-derived yeast lipases toward industrial application.