Why Costco's Kirkland Milk Takes Longer To Expire Compared To Other Brands

Milk is a staple ingredient with countless applications, from baking to gravies to sauces to cereals — some even enjoy a glass on its own. Practically everyone knows the frustration of finding expired milk in the refrigerator, but some Costco customers have noticed that their Kirkland Signature milk seems to last a few days longer than other brands. Why is that?

Costco's in-house milk brand most likely outlasts the competition due to the company's strict quality standards, some of which go above and beyond federal regulations. As elucidated in Costco's 2023 supplier guidelines, lead auditors serve no more than three years before the company rotates them out for fresh perspectives. But production facilities must also stay on their toes.

All of Kirkland's U.S. milk suppliers (both dairy farms and processing facilities) must pass at least one surprise inspection per year, and if the supplier is based in China, that minimum raises to two. Scoring 85% or less means re-inspection within two months. Not only that, but Costco also keeps a close eye on the water used for processing, and the milk itself faces 60 different microbial tests. Just one failure means the milk will never see store shelves.

Given Costco's extensive safety precautions, you may be wondering why more people don't buy Kirkland Signature milk. Unfortunately, this brand also has a few drawbacks that irk consumers. Kirkland milk is considered both one of the best and worst dairy products at Costco, as customers appreciate the shelf life but find that the gallon bottle's square shape makes mess-free pouring a challenge.

Customers also find other aspects of this brand frustrating. Kirkland's reduced-fat milk sometimes contains dark specks, which thankfully aren't dangerous but are still visually off-putting. Costco adds dehydrated milk solids to its reduced-fat milk to boost protein levels, and according to a Reddit user who works for a milk pasteurizing plant, these solids are sometimes scorched by the heat used for dehydration, resulting in unsightly specks.

Another complaint regarding the brand's milk is a bit unusual for the discount store. Some consider Kirkland's milk to be one of the most seriously overpriced items at Costco, as it can be a few cents pricier per gallon than the competition. But milk prices vary by location and time, and others have found that Kirkland's milk is generally more affordable than other store brands. Even if it is more expensive, customers can rest easy knowing that Kirkland's milk will likely last several days beyond its sell-by date.