Evaluation of two alternative techniques for counting mesophilic aerobic bacteria in raw milk

Abstract

Traditional techniques of microbiological analysis do not meet the current needs of having immediate analytical results in order to be able to make decisions in the process of food manufacturing, specially in HACCP application systems concerned with quality assurance. The development of modern techniques is showing new alternatives but it is important that the advantages for each of these new methodologies be considered for each application. The objective of this paper was to evaluate the advantages of two microbiological alternative techniques (dry rehydratable film and direct epifluorescent filter technique), applied to enumerating total aerobic mesophilic micro-organisms in refrigerated raw milk supplied by dairy farms, compared to the reference technique (standard plate count). The two alternative techniques under study showed good correlation levels with the standard in plate technique. Dry rehydratable film technique had higher costs but this technique allows the analysis of twice the quantity of samples in the same unit of time compared to the standard plate technique. This compensates for the higher costs. The epifluorescent technique gave the results in shorter time but it is necessary to use sophisticated equipment and trained personnel. Therefore, it is preferred when having the appropriate infrastructure.