Anthea Stolz took a summer job at a cheese counter in 2004 and turned it into a career. She is now the cheese buyer at Bi-Rite Market in San Francisco.

The level of attention given to cheese care at a market is often the most important indicator of quality, regardless of whether it’s cut to order or precut and wrapped. Generally speaking, though, buying cheese from a shop that custom-cuts your cheese just before purchase is ideal, since a minimum amount of the cheese’s surface area has been exposed to things that can spoil it, such as rogue bacteria, oxidation, and off odors (the smell of a stale refrigerated cheese case is the worst!). It may cost a bit more, but spending a little extra on fresh-cut cheese is often worth it, especially if you buy just what you’ll eat within a couple of days. Best of all, when you buy cheese from a full-service monger, you can sample it first to be sure it’s up to your standards.

That said, even cheesemongers committed to a cut-to-order program know that time-pressed shoppers need a grab-and-go selection of wrapped cheese to choose from. The best of these are filled with small cuts of popular cheeses that will sell within three or four days so the stock can be continuously rotated. Diligent mongers will also scrape and rewrap any cheeses that have been in plastic more than a few days, or they’ll wrap the cut cheeses in special two-ply cheese paper to protect their quality. With such frequent handling, the experienced monger is better able to assess the shelf life of every cheese on sale. And therein lies the secret to buying great cheese—from the counter or the case.

Traditionally, buttermilk refers to the liquid portion that remains after butter has been churned from whole cream. Before the invention of the centrifuge in the 19th century, butter-making and the separation of milk and cream relied on gravity and time. Milk was left overnight to allow the cream to rise, and during that time the milk began slowly to ferment. In the morning, cream was skimmed from the top and churned into butter. Fermentation in the remaining liquid would have continued, thickening the remaining buttermilk and continuing to develop its tangy flavor.

Most buttermilk, however, that is commercially available in the United States is actually skim or low-fat milk that has been heated to concentrate its proteins and create a thicker texture, then fermented with cultures until the milk gels slightly. The liquid is then cooled to stop the fermentation and gently agitated to break the curd into a smooth liquid. True buttermilk is more flavorful, less acidic, and more bioactively complex than its commercial counterpart. It is also, however, far more perishable and prone to off flavors, making it more challenging to bring to market.