Why your Costco milk is lasting longer than what the expiration date says

Costco reportedly puts its Kirkland-brand milk through rigorous testing that results in it not spoiling even past its printed expiration date.

Don’t have a cow: Your Costco’s Kirkland-brand milk might last way longer than expected.

Customers of the big-box store are discovering that its milk consistently lasts well beyond its expiration date and trying to figure out why. A resurfaced Reddit forum shows users in agreement that their milk doesn’t spoil as quickly, sometimes even being good a week after its expiration date.

“I get the organic Costco milk now because even if we don’t go through all three half gallons before I go back to Costco (every 2 -3 weeks). The milk is still good. We save money by buying it from there,” one person wrote in the two-year-old thread.

While this may sound udderly shocking, there could be an explanation for it. The FDA’s Pasteurized Milk Ordinance mandates quality thresholds, but Costco reportedly takes its inspections and testing even further to make its milk last longer.

Costco requires Kirkland milk suppliers to undergo at least one surprise inspection annually, and twice a year if the facility is in China, according to its 2023 Food Safety & Quality Audit Expectations. The chain’s practices is why some say its milk last longer than expcted. (AFP via Getty Images)

Under federal law, Grade A milk must meet basic safety metrics, such as keeping total bacteria below 100,000 colony-forming units and chilling milk to under 45°F within two hours of milking.

But according to Food & Wine, Costco’s suppliers are held to much stricter standards. Costco’s rigorous testing ensures its milk maintains consistently low bacteria and cell counts.

Each facility producing Kirkland milk undergoes at least one unannounced audit annually, twice in China, with severe consequences for scores below 85 percent, according to Costco’s 2023 Food Safety & Quality Audit Expectations.

Every milk batch is put through roughly 60 microbial tests, and even a single failed result can stop it from being shipped.

Water used in processing is strictly monitored, with quarterly testing of private wells and rigorous rotating lead auditors to avoid complacency. Milk from healthier herds, measured by lower somatic cell counts, is known to have a longer fridge lifespan.

Milk from healthier cows, with fewer bacteria and lower somatic cell counts, tends to stay fresh longer, particularly when processed under rigorous standards like those used by Costco. (Costco)

Herds with averages under 200,000 cells/mL are deemed “top-tier,” while those exceeding 400,000 cells/mL tend to spoil faster.

Milk from healthier cows with lower bacteria and somatic cell counts lasts longer, especially under strict processing standards like Costco's. This results in less food waste and keeps customers in a good mood by reducing the need to buy milk as often.

The Independent has contacted representatives for Costco for comment.