Kluyveromyces marxianus: a promising alternative to baker's yeast Saccharomyces cerevisiae for enhanced oven rise performance during bread baking.

For millennia, bread making has relied on Saccharomyces cerevisiae, valued for its efficient sugar fermentation, robustness under processing stresses and production of a desirable flavour profile. Nevertheless, there is growing interest in exploring alternative yeast species that show advantageous traits beyond the physiological boundaries of S. cerevisiae. For example, a yeast's ability to stimulate dough oven rise is of particular interest because it determines loaf volume. It was recently shown for S. cerevisiae that dough oven rise strongly correlates with yeast viability and thermotolerance during baking. In this study, we evaluate the impact of Kluyveromyces marxianus, a yeast species known for its exceptional thermotolerance, on dough oven rise. K. marxianus strains exhibited a broader range in oven rise (13.3-41.5%) than previously reported for S. cerevisiae. The best-performing strain also showed greater oven rise than the industrial baker's yeast and the top-performing S. cerevisiae strain reported in a previous study using the same electrical resistance oven (ERO) setup. Similar to what has been reported for S. cerevisiae strains, we observe a positive correlation (R2 = 0.77) between viability and oven rise, suggesting that cell survival is a key contributor in early baking performance. Additionally, differences in CO2 release behaviour were observed between strains. While no individual CO2-release parameter directly correlated with oven rise, the strains exhibiting the highest oven rise generally showed slower CO2 release than the poorest-performing strain. Together, our results demonstrate the potential of non-Saccharomyces strains for improving oven rise performance, which could lead to applications increasing loaf volume.