The volatile thiol 4-mercapto-4-methylpentan-2-one (4MMP) is a potent contributor to wine aroma. In grape juice, 4MMP is bound to cysteine as a non-volatile compound and requires the action of yeast during fermentation to release the aroma active thiol. A method was developed to measure 4MMP release from the precursor by headspace solid-phase microextraction and separation by gas chromatography with atomic emission detection to screen the ability of wine yeast to release 4MMP. Yeast commonly used in white wine making were grown with the precursor at two different temperatures, and the amount of 4MMP released was measured. The results demonstrate that yeast strain selection and fermentation temperature can provide an important tool to enhance or modulate the grape-derived aromas formed during wine fermentation.