Effects of sugars in growth media,diluents and enumeration media on survival and recovery of Saccharomyces cerevisiae heated in peach puree

Thermal resistance, injury and recovery of Saccharomyces cerevisiae heated in peach puree were studied. The effects of sucrose, glucose and fructose in puree and in recovery media were avaluated. In addition, the influence of sucrose in growth media and diluent on susceptibility to injury and extent of resuscitation were examined. Cells cultured in broth supplemented with sucrose had increased resistance to heat. The presence of sucrose, glucose and fructose in peach puree protected cells against thermal inactivation, whereas sucrose tended to be less inhibitory to stressed cells in enumeration media when compared to glucose and fructose. Repair of heat-stressed cells was retarded by holding cells in diluent containing sucrose and a reduced level of peach puree. These observations must be considered if pasteurization processes for peach products such as puree and concentrate are to be optimized. Results will also be of value to those selecting procedures for enumerating thermally injured yeast cells.