FIBER OPTIC SENSOR FOR PREDICTING THE CUTTING TIME OF COAGULATING MILK FOR CHEESE PRODUCTION

A fiber optic sensor was developed to measure the changes in diffuse r eflectance of coagulating milk using infrared light at a wavelength of 950 nm. Reflectance profiles were measured during tests in which the coagulating temperature, pH, enzyme concentration, and milk fat conten t were controlled. All reflectance profiles showed an induction, sigmo idal, and logarithmic period The diffuse reflectance was found to be a function of milk fat content and affected by milk pH, temperature, an d enzyme concentration. Parameters generated from the reflectance prof ile were analyzed for correlation with observed cutting time. The time between enzyme addition and the occurrence of the sigmoidal inflectio n was found to be correlated with observed cutting time. Change in dif fuse reflectance measured between enzyme addition and the observed cut ting time was not found to contain information for predicting cutting time. Cutting time prediction models were generated by incorporating t he inflection time, a normalized reflectance ratio, and milk coagulati on temperature into multiple linear regression equations. The predicti on equations were considered to have potential for commercial applicat ion, but need further research to expand the conditions over which the y are applicable.