Effects of Lactic Acid Stress on the Solid-state Fermentation of Pichia kudriavzevii

Nongxiangxing Baijiu distiller’s grains are rich in lactic acid. Pichia kudriavzevii is the dominant yeast. The effects of lactic acid on the solid-state fermentation characteristics of Nongxiangxing Baijiu of the dominant yeast were explored under lactic acid stress of different concentrations. The growth and metabolism changes of Pichia kudriavzevii (PY1) were investigated from the aspects of carbon source consumption, growth factor utilization, high temperature tolerance and main metabolite production. Results showed that, the lactic acid stress had no significant effect on the colony and cell morphology of P. kudriavzevii, but had a certain inhibition on the growth of cell. This reversible inhibition could be weakened by amino acids and vitamins. When the culture temperature exceeds 44 ℃, the effect of lactic acid on the growth of the strain was gradually replaced by temperature. In metabolism, lactic acid could improve the utilization rate of glucose, galactose, maltose, fructose and sucrose, increase the production of ethanol and esters, and reduce the production of higher alcohols. In summary, the lactic acid could affect the flavor formation of Nongxiangxing Baijiu by affecting the growth and metabolism of yeast, and could be used as the fermentation regulation factor of Nongxiangxing Baijiu.