Puerto Rican dairy processor uses cutting-edge pasteurization to redefine fresh milk category

In May, Tres Monjitas switched from HTST pasteurization to MST to pasteurize its fresh milk products. The company retrofitted its existing heat exchanger with an MST chamber. When the raw milk arrives at Tres Monjitas, the milk undergoes laboratory testing to ensure it meets quality requirements and then moves through a series of filters. The filtered milk is pumped into the MST chamber, where it is subjected to a temperature of about 140°F. As the liquid is pushed through a spray nozzle, it forms into small droplets at a speed of 10 meters per sec. The chamber increases the droplet temperature to about 158°F, while the pressure drops to between 150 and 160 psi. Unlike a stream of liquid, the droplets don’t have much cushioning to protect the microbes that may be in them, leaving the bacteria unable to survive the shock that comes when the temperature increases and the pressure declines suddenly in the droplet. That shock ruptures the microorganisms’ protective membrane and destroys the bacteria, achieving an efficient 8-log bacteria reduction that can extend the milk’s shelf life without damaging its nutritional components and flavors. The milk then undergoes HTST pasteurization in order to comply with the food safety regulations of third-party agencies, including FDA.

“The thing that is unique about [MST] is that nobody thought to form droplets out of the milk to explode the microbe,” explains Philip R. Frechette, founder and CEO of JCS.

Vaquería Tres Monjitas processes about 150,000 quarts per week of fresh milk with Millisecond Technology.Photo courtesy of Vaquería Tres Monjitas.

Milking the benefits

By using MST pasteurization, Tres Monjitas has been able to extend the shelf life of its fresh milk products from 12 or 13 days to 33 days. That has helped the company minimize yield losses, decreasing the amount of expired product that retailers pull off their shelves and return to the company. It also reduces Tres Monjitas’ wastewater treatment costs because it now disposes of less milk. “That equates to about 18 percent of the losses due to out-of-date-code milk,” says Orlando González, general manager for Tres Monjitas. “So if you can get the 30 days on your date codes, you won’t have as many returns.”

With the extended shelf life of its fresh milk products, Tres Monjitas is now able to expand to new markets outside of Puerto Rico. As the first company to commercially use MST, Tres Monjitas purchased the exclusive rights to use the technology for distributing its fresh milk products in Puerto Rico and the U.S. Virgin Islands. The longer shelf life means the products can travel farther and can differentiate themselves from other milk brands that use traditional pasteurization methods because Tres Monjitas’ fresh milk products are in a category all its own, according to González.

“[MST] really offers us the opportunity to enter new dairy markets like the Virgin Islands because we are now more competitive in relation to other dairy companies,” he explains. “Most of them are producing UHT-processed milk with more than 30 days shelf life or HTST milk with a shorter shelf life. We are able to compete with them because we’re in a different category: fresh milk with a long shelf life. It is the perfect match of shelf life and flavor. It stands out in the coolers with our customers.”

“This new technology takes pasteurization to new levels,” González adds.  “With MST, we are the first long-life pasteurized fresh milk in the world with the same great flavor and nutritional value.”