Growth Response of an Osmotolerant Sorbate-Resistant Yeast, Saccharomyces rouxii , at Different Sucrose and Sorbate Levels.

Effects of preconditioning Saccharomyces rouxii to various sucrose and sorbate concentrations were investigated. Cells were preconditioned to 0 and 60% (wt/vol) sucrose without and with 0. 1% (wt/vol) sorbate by a series of four transfers in potato dextrose broth (PDB). The preconditioned cells were inoculated in growth medium containing 0, 30, or 60% (wt/vol) sucrose with 0. 0.05, or 0.1% (wt/vol) sorbate and in chocolate syrup without and with 0.1% (wt/vol) sorbate. Preconditioning of S. rouxii cells to 0 and 60% sucrose offered no advantage for growth in a medium containing 0, 30 or 60% sucrose. When S. rouxii cells were preconditioned in 0.1% sorbate, an increased resistance to sorbate occurred. S. rouxii cells preconditioned in 60% sucrose/0.1% sorbate were more sensitive to sorbate than cells preconditioned in 0% sucrose/0.1% sorbate. Regardless of the sucrose level, S. rouxii cells, preconditioned in 0. 1% sorbate showed an increased resistance to sorbate when inoculated into the growth medium and the chocolate syrup.