Milk collected from the udders of healthy cows is almost sterile but microbial contaminants are introduced during milking, storage, processing, and distribution. Cleaning and sanitation failures allow contaminating organisms to accumulate in dairy processing equipment, potentially leading to the development of biofilms that can become a significant and persistent source of contamination. On the farm and…
Throughout this series on dairy microbiological testing, we have discussed the types of micro tests that can be used to enumerate the classifications of bacteria we are concerned with in fluid milk processing. The first two articles discussed Gram-negative bacteria in raw milk and the effects of Gram-positive heat resistant thermoduric/psychrotrophic spore formers (HRSF) on…
The first article in this series, Raw Milk Dairy Micro Testing, focused on Gram-negative bacteria in raw milk with the Preliminary Incubation (PI) Count and Fresh Standard Plate Count (SPC) tests. The second article, The Effects of Gram-positive HRSF Bacteria on Fluid Milk Shelf Life, discussed another classification of bacteria that was not known as…
On March 22, 2023, the QualiTru team met at the University of Minnesota’s Department of Food Science and Nutrition for an educational pilot plant tour led by Darrell Bigalke, founder of QualiTru Sampling Systems, dairy microbiologist, entrepreneur, and proud University of Minnesota alum. As part of the celebration of QualiTru’s 40th anniversary, the team had…
The first article in this series, Raw Milk Micro Testing, focused on Gram-negative bacteria in raw milk with the Preliminary Incubation (PI) Count and Fresh Standard Plate Count (SPC) tests. In this second installment, I would like to discuss another classification of bacteria (Gram-positive HRSF Bacteria) that was not known as a major issue in fluid…
Why do you do it? What do the test results tell you? Is the test you use still a valid one? In part one of this dairy micro testing series, Raw Milk Dairy Micro Testing, I would like to take you on a journey through the development of some of the principal tests used in…
The significant food safety recalls that have occurred in the dairy processing industry this past year, ranging from Listeria outbreaks in ice cream to Cronobacter in infant formula, and the Food and Drug Administration’s* (FDA)’s recent publication of its revised Investigations Operations Manual draw attention to the criticality of inline process monitoring of bacterial risks,…
Membrane filtration is a widely used process in the dairy industry that separates specific components of milk and whey and then either concentrates or removes/reduces them. The technology used in cheese-making, whey protein concentration, fractionation of protein, and numerous other dairy processes requires special sampling considerations for both regulatory purposes and component analysis. It is…
The shelf life of pasteurized fluid milk is challenged by bacterial contamination that enters the finished milk supply through two portals: a) contamination by Gram-negative psychrotrophic bacteria during processing after pasteurization; and b) contamination by Gram-positive spore-forming bacteria that enter primarily through the raw milk supply. In today’s processing environment, where post-pasteurization contamination is largely…
Post-pasteurization contamination in dairy plants is a warning signal for potential food safety and spoilage concerns. While having an effective sanitation program gets the most attention, good sanitation alone cannot guarantee product quality and food safety. Sampling and testing products during processing are critical for identifying potential sources of post-pasteurization contamination. Possible causes of post-pasteurization…
Founded in 1983, QualiTru Sampling Systems (formerly known as QMI) is the trusted partner that delivers accurate, in-process aseptic, representative, sanitary, and hygienic sampling solutions for the dairy, beverage, and liquid food industries. Read more…
