Cal Poly Creamery Students Earn Pasteurization Licenses, Boosting Dairy Production and Training Opportunities
By: Lauren McEwen (Agricultural Communication, ’25)
The delectable ice creams and cheeses made at the Cal Poly Creamery, like all dairy products, undergo strict processing regulations to ensure they are safe for consumption. Marissa Johnston, fourth-year food science major, has worked at the Cal Poly Creamery for three years and recently became a licensed pasteurizer through the California Department of Food and Agriculture (CDFA) by taking an all-encompassing exam.
Pasteurization is a heat processing method integral to dairy production because it kills pathogens. The licensing test is a lengthy oral, written and practical examination. Johnston and fellow student manager Jenna Bates, a fourth-year agricultural systems management major, both passed the certification in June, allowing them to operate pasteurization equipment at the Cal Poly Creamery, as required by the CDFA.
For Johnston, a passion for dairy products is a driving force behind the effort. As a production student manager at the Cal Poly Creamery, she assists with daily operations, including making products such as Cal Poly cheeses and ice cream, as well as training incoming students. The certification will allow her, alongside Bates, to operate the pasteurizer and train additional students to get their certification. In addition to her work at the Creamery, Johnston helps run the Milk Quality and Products judging contest at the annual California State FFA Judging Finals held at Cal Poly and is a CAFES Ambassador representing the Food Science and Nutrition Department.
The breadth of information gained through her food science degree has prepared her for the daily milk processing tasks. “All the courses I take apply directly to my work at the creamery,” Johnston said. “Within food science courses I learn all aspects of food production including food safety, food processing, chemistry, microbiology and more.”
She says that obtaining the pasteurizer’s license is important to the Cal Poly Creamery to increase efficiency and to provide Learn by Doing opportunities to fellow student employees. In all, as many as 25 students work there during the academic year, gaining hands-on skills in all aspects of dairy production, packaging and selling dairy products.
“This will allow us to operate the pasteurizer and eventually pass down our knowledge to the underclassmen as they will eventually take the test,” said Johnston. “Beyond Cal Poly, this certification can be renewed and used at other milk production companies. The knowledge gained can also apply to many other industries, as thermal processing is used for many other food products.”
Visit Cultivate Summer 2025 to read more stories.