Valorisation of olive oil by-products into pectic- and glucuronoxylo-oligosaccharides via one-step fermentation

Olive pomace (OLP) and stones (OLS) are key by-products of olive oil production, rich in lignocellulose and pectin, making them viable substrates for prebiotic oligosaccharide (OS) production. This study evaluated the chemical composition of OLP and OLS powders (OLPp and OLSp) and their potential for OS production through one-step fermentation using recombinant Bacillus subtilis 3610. Both substrates had comparable xylan and pectin levels, but OLSp showed greater potential, achieving a maximum total sugar yield of 60 ± 3 mg.g^-1 after 12 h under optimal conditions (20 g.L^-1 OLSp, pH 7.0, 45 °C). The resulting OS mixture from OLSp was predominantly composed of pectic oligosaccharides (72.1 %mol) and glucurono-xylooligosaccharides (11.6 %mol). This innovative process, competitive with commercial enzymes, highlights the potential of by-product valorisation for producing value-added food compounds. The findings provide insights into low-cost bioprocesses and underscore the importance of sustainable approaches in the industry of functional food ingredients.