An automatic procedure for rapid online estimation of raw milk quality

A simple and inexpensive automatic procedure for rapid online assessment of raw milk microbiological quality was developed as an alternative to the presently available methods, which are either time consuming or require costly instrumentation. The technique was based on the monitoring of change in color of milk in methylene blue dye reduction test due to metabolic activity of the viable bacterial cells. The change in dye color was related to the output voltage signal of a specially designed light sensing probe (LSP) for about 40 min. The models developed for estimating SPC and MBRT from LSP output voltage showed R-2 of about 0.814 and 0.803, respectively. Subsequently, the output voltage of LSP was interfaced with a PC to predict and display the SPC (cfu/ml) and MBRT (h) of raw milk along with its quality grade in real time. The predictions of raw milk quality grades based on the calibration of LSP output voltage with SPC and MBRT were in good agreement with actual grades showing considerable promise for this novel assessment technique. (C) 2005 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.