The Secret Reason Costco’s Milk Stays Fresh Long After It's Expired

If you’ve ever noticed that Costco’s Kirkland-brand milk seems to outlast the expiration date on the jug, you’re not alone, and it’s not just your fridge. Shoppers have been talking about it online for years, sharing stories of how their Costco milk stays fresh days, sometimes even weeks, past its sell-by date.

Now we know why.

It turns out Costco’s milk supply chain runs a tighter ship than most other dairy brands. According to Food & Wine, while federal law requires all Grade A milk to meet minimum safety standards...