The Production of an Economical Culture Medium from Apple Pomace for the Propagation of Non-Conventional Cidermaking Yeast Starters

Abstract

The aim of the present study was to evaluate the use of different chemicaltreatments of apple pomace in order to produce an economical culture medium for thepropagation of two non-conventional yeast strains. An experimental design approach wasused for the optimization of the hydrolysis conditions of apple pomace. Both acid andalkaline treatment conditions were tested. The optimal hydrolysis conditions to disruptthe pomace lignocellulosic structure were 1% w/v of H3PO4, 121 ◦C, and 40 min for acidtreatment, while 6% w/v of NH4OH, 20 ◦C, and 2 h were optimal for the alkaline condition.Saccharomyces uvarum NPCC 1420 and Saccharomyces eubayanus NPCC 1292 yeasts were ableto grow in the liquid fraction obtained from both acid and alkaline treatments. However,the medium with the acid treatment was found to be more suitable for yeast growth,showing, for both strains, higher μmax and biomass production and lower td and λ thanthat observed for the medium with the alkaline treatment. According to the growthparameter analysis for both strains, the acid treatment was selected for further studies.By taking advantage of this agroindustrial by-product, a circular economy approach ispromoted, reducing environmental impact and fostering sustainable development.