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Many households shopping at Costco routinely pick up a bottle of Kirkland Signature, the store's private-label fresh milk. However, some consumers have noticed that this milk seems to last longer than expected—even slightly past the date printed on the packaging, it often shows no obvious signs of spoilage. Why does Costco's Kirkland milk stay fresh for so long?

And does the date on the package mean it must be discarded immediately upon arrival? Why Is Costco's Kirkland Milk More Durable?

According to U.S. media outlet The Takeout, the reason Kirkland milk has a longer shelf life lies in stricter testing standards and lower bacterial counts. During production, this milk not only meets the U.S. government's Pasteurized Milk Ordinance requirements but also undergoes more rigorous quality control than standard regulations.What Tests Does Kirkland Milk Undergo Before Reaching Shelves?

To maintain low bacterial levels, the factories producing Kirkland milk are subject to unannounced inspections. Even the water used to clean equipment is tested for contaminants. More importantly, the milk must pass at least 60 microbial tests before being placed on shelves. Due to this strict quality control, Kirkland milk has lower bacteria levels than most other brands, resulting in a naturally longer shelf life.Can You Still Drink It After the Expiration Date?

To determine whether milk is still safe to drink, it's important to assess its actual condition, not just the printed date. According to the U.S. Department of Agriculture (USDA), pasteurized milk generally maintains good quality for at least seven days beyond the labeled date if kept refrigerated continuously. As long as the milk doesn't have a sour smell, hasn't curdled, and still appears smooth, it is likely not spoiled.