Effect of Saccharomyces cerevisiae Live Cell and Treated with Heat and Acid on Citrinin and Pigments of Monascus purpureus

Monascus purpureus can produce a wide range of natural pigments so attract the attention of food producers as substitute of synthetic colors. Monascus pigments usually accompanied with citrinin contamination which limits their wide application in foods. The usage of Saccharomyces cerevisiae is known as a useful biological way for citrinin elimination. In this study, the effect of Saccharomyces cerevisiae cells in twomodes of treatment (heat treatment at 121 °C and acid treatment in 2M HCL) and live at three different concentrations (103, 104, 105 CFU/mL) were investigated on the amount of citrinin and yellow, orange and red pigments produced by Monascus purpureus. The results showed that live yeast cell and yeast cells treated by heat and acid significantly decreased the citrinin in culture, so that citrinin content decreased from 4.43 mg/L in control sample to 0.9, 0.10 and 0.07 mg/L (at 105 CFU/mL yeast suspension) respectively. The maximum amount of yellow, orange and red extracellular and intracellular measured pigments belong to the samples with live yeast, while the amount of this pigments in the samples containing yeast treated with heat and acid reduced respectively. Among the treatments, the use of live yeast at concentration of 104 CFU/mL per milliliter provided the best conditions to achieve the desired goal.