Microbes and their toxins form the biggest safety problem in food processing and storing. In dairy industry, milk - both as a raw material and in various products - needs to be tested for microbiological quality control. The conventional methods used are based on plate count techniques. These techniques include several disadvantages; i.e. they are labour intensive, the final results are generally obtained three days after starting the analysis, and the repeatability is poor. Thus, increasing demands have arisen for more rapid and automated methods with high capacity. In spite of decreasing the economical losses during the production, rapid methods decrease the storage time of ready-made products increasing the actual shelf-life of the product.

This application sheet shows how quality control of milk can be performed with Bioscreen.

PRINCIPLE OF THE TEST

1.) To get CFU values first calibration files (Bioscreen against standard plate count) must be created with representative samples (60-100 samples with great variation in number of bacteria is recommended). Then in the routine use BIORTN program counts automatically the number of bacteria (cf. more detailed inormation in the generalapplicationi instruction).

2.) For photometric reasons the final background turbidity is the cuvette must not be higher than 0.5 abs. units. This is why milk must be diluted (1:10 dilution is generally enough followed by using 30 ul as dispensing volume) before dispensing it into the cuvette.