The effects of the temperature and pH on the heat degradation of the orange and red pigments produced by Monascus ruber CCT 3802 were determined in a jacketed glass bottle. The orange or red pigments were added to 300 mL of buffer solution and the initial absorbance adjusted to approximately 1 UA470 nm and 1 UA510 nm, respectively, in a Spectronic Unicam Genesys 10vis spectrophotometer. The pigment solution was transferred to a 400 mL jacketed glass flask with water circulation at the temperature of the assay. The temperature was controlled by circulating water from a Microquímica Model MQBMP-01 water bath through the jacket of the glass flask. The flask was maintained at the selected temperatures and periodically agitated with a magnetic stirrer to ensure a uniform temperature throughout the bulk of the sample. The temperature of the sample at its geometric center was monitored using a thermometer. The pigment solutions were heated for approximately 120 min, and samples collected after pre-determined time intervals. The first sample was collected after attaining constant temperature and immediately transferred to an ice water bath. The absorbance was measured in a spectrophotometer.