Milk: Quality, Consumer Interest Research Abound in Top Three Dairy States

Dr. Wiedmann supervised research published in 2018 that showed refrigeration at 39.2 degrees Fahrenheit had a dramatic effect on lowering the mean concentration of psychrotolerant spore-formers in simulated half-gallons. “Specifically, our what-if simulations of lowering the refrigeration temperature from 42.8 degrees Fahrenheit to 39.2 degrees Fahrenheit indicated that only 9 percent of half-gallons of milk would be spoiled (greater than 20,000 cfu/mL) by 21 days when stored at to 39.2 degrees Fahrenheit, compared with the initial 66 percent of half-gallons spoiled by 21 days when stored at 42.8 degrees Fahrenheit,” he relates. “This translates to an extension of average shelf life (time to reach greater than 20,000 cfu/mL) by nine days by lowering the storage temperature from 42.8 degrees Fahrenheit to 39.2 degrees Fahrenheit.

“If a milk plant is well run and if there is no post-pasteurization contamination, the high temperature/short time (161 degrees Fahrenheit for 15 seconds) shelf life can be expected to be 24 to 30 to 35 days if milk is refrigerated at less than 39 to 40 degrees Fahrenheit,” Dr. Wiedmann points out.

DNA fingerprinting through whole-genome sequencing is now helping scientists to better understand and decrease spoilage organisms in milk, Dr. Wiedmann says. That’s a good thing, he says, because pictures of spoiled food, including milk, are often posted on social media. “Pictures of off colors and spoilage issues can be damaging to the food industry,” he emphasizes, mentioning his related collaborative research published in 2019 that used whole-genome sequencing of nine Pseudomonas spp. bacteria isolates to determine the cause of blue and gray pigments in cheese and milk, respectively.