Effect of water activity and temperature on growth of Penicillium citreoviride and Penicillium citrinum on MiGao (rice cake).

Contamination by mold is a serious problem in steam-cooked rice cake, a traditional Chinese food. Growth responses to different temperatures and water activity values for Penicillium citreoviride and Penicillium citrinum, two of the most common molds, were investigated. Partial least square regression analysis showed that the growth of the two fungi did not differ in response to changes in water activity and temperature. Optimum water activity for growth was 0.90 and optimum temperatures for growth were 30 degrees C in most cases.