Enhanced survival of fluidized bed-dried microencapsulated Saccharomyces cerevisiae cells in the presence of Hongqu rice distiller's grain peptides

Saccharomyces cerevisiae (strain JH301) cells were micro-encapsulated in microcrystalline cellulose and Hongqu rice distiller's grain peptides (HRP) and subjected to fluidized bed drying. The effect of HRP on the viability of yeast in response to thermal drying was investigated. The moisture-viability profiles showed that HRP reduced the drying rate of yeast cells and increased viability in a concentration-dependent manner. Scanning electron microscopy revealed that HRP protected the morphology of the yeast cells, which presented a normal smooth structure and compact shape after thermal drying. The results of low-field 1H nuclear magnetic resonance and infrared spectroscopy revealed that HRP controls the binding water of yeast powder as opposed to interacting with the membrane surface proteins, further reducing the damage to phospholipids in the cell membrane during drying. Flow cytometry and confocal laser scanning microscopy confirmed that 3% HRP could reduce the proportion of membrane-damaged cells by nearly 19%. After drying, the proportion of unsaturated fatty acids in the cell membrane of JH301-3% HRP was 10.36% higher than that of JH301 in the absence of HRP, achieving increased membrane integrity and higher ATPase activity after rehydration.