Comparison between different agri-food residual streams as direct source of biosurfactants

In this work various residues were evaluated as direct source of biosurfactants, observing that those coming from the wine, cider, and potato chip industries exhib-ited limited potential as direct sources of biosurfac-tants. Consequently, it should be recommended to evaluate their use as nutritional supplement with other residues in controlled fermentation process rather than use them as direct source of biosurfactants. Notably, winery streams exhibited a lower profile for the sponta-neous generation of biosurfactants. In contrast, dairy products, particularly sour buttermilk, olive oil residues, and Brewer’s spent grain residues, gave promising results for considering them as natural sources of biosurfactants. These biosurfactants were able to reduce water surface tension (ST) by approxi-mately 20 units exhibiting in some cases critical micel-lar concentration (CMC) values lower than 0.1 g/L. Furthermore, this study aligns with previous research where it was demonstrated the effectiveness of corn steep liquor, a subproduct of wet corn milling industry as direct source of biosurfactants.