A Reflectance Colorimeter Instrument for Measurement of Microbial and Enzymatic Activities in Milk and Dairy Products

A reflectance color meter has been combined with a Zymate II robot and incubator to measure microbial and enzymatic activity in dairy and food products. Microwells are automatically filled with samples, dyes, and media, and the plates are intermittently removed during incubation to measure color changes of the dye(s). Traditional pH, metabolic, or O/R dyes can be used. The instrument can be programmed and media/dye selected for more rapid estimation of antibiotics, microbial numbers, abnormal milks, coliform counts, product shelf life stabilities, yeast counts, staphylococcal counts, enzymes and culture activity tests, etc. Antibiotic test data are similar to that obtained with impedance instrumentation. Where fewer samples per day are processed, models requiring manual sample preparation are described.