Effect of pulsed electric fields on the production of yeast extract by autolysis

The production of yeast extract by autolysis can be accelerated by treating yeast cell suspensions with pulsed electric fields (PEF) prior to autolysis. The present work is aimed at investigating the effects of PEF on the progress of yeast autolysis. Saccharomyces cerevisiae suspensions (8.3 log CFU/mL in distilled water) were subjected to various PEF treatment conditions (5-20 kV/cm, 1-2000 pulses, 15-mu s pulse width) corresponding to various values of cell disintegration index (0-1). Suspensions were then autolyzed and the production of yeast extract was monitored in terms of total protein, amino acid and total solids release. PEF treatment led to an increase of final amino acid and total solids release of 37% and 20%, respectively. Autolysis was described mathematically by a first-order fractional model through which PEF treatment was found to accelerate the progress of autolysis up to 78% compared to untreated samples.