Evolution of the quality of baker’s yeast pellets containing a carrier during their convective drying

Abstract

The addition of a solid carrier before drying seems a promising way to improve the processability and the drying kinetics of yeast pellets. However, its influence on the quality of the yeasts during and at the end of the drying is not yet well understood and is investigated in this communication. A yeast paste was mixed with different amounts of wheat flour, a solid carrier, to obtain pellets with 69, 55, and 40 wt% moisture content. The fermentation activity of the yeasts was measured in samples taken throughout the drying process of these pellets. The experimental results highlight that the addition of a carrier does not significantly alter the quality of the yeasts before drying but has a negative impact on their final quality at the end of the drying process. Moreover, the addition of a solid carrier leads to a continuous decrease in the fermentation activity of the yeasts from the beginning of drying, in contrast to the activity of the yeasts in the absence of a carrier, which remains high during drying, as long as the moisture content of the pellets is larger than about 0.5 (d.b.).

Keywords:

• Yeast
• drying
• carrier
• quality
• fermentation activity

Acknowledgments

We gratefully acknowledge support of the FRS-FNRS, Belgium, and of the NSERC-CREATE program, Canada.

Appendix

Appendix A: SEM images

Figure A.1. SEM images of the mixture between yeast paste and wheat flour.

Appendix B: Drying curves

Figure B.1. Time evolution of the moisture content of the pellets for the three sample groups at 40 °C - adapted from our previous paper.^[22]

Additional information

Funding

Fonds De La Recherche Scientifique - FNRS; NSERC.