Most U.S. food companies stamp lot codes and/or expiration dates on their products. But what do all these numbers really mean? The Institute of Food Technologists offers these answers. There are two types of codes:

1.  Lot Code: When manufacturers produce a product, they do so in batches. Each batch is given a unique series of numbers that makes it possible for manufacturers to track exactly when a problem occurred and which products need to be recalled.

2. Expiration Dates: These are numbers represented in a date format that tells consumers when a food product is either no longer safe to eat or might not taste as good as it did when originally produced.

There is little government regulation when it comes to expiration dates stamped on packages. According to the Department of Agriculture Food Safety and Inspection Service, there are a few different types of dates you should look for:

•  Sell By is a guide for stores to know how long they can display a product before its quality begins to weaken. You can eat an item for some time after the “sell by” date.

•  Best if Used By/Best Before is a guide to the quality or flavor profile of the food and does not refer to safety. For example, sour cream may grow increasingly sour over time, but it remains safe to consume.

•  Use By is the closest to an expiration date. Using products after the date is not recommended. In some cases, food may lose nutrients, develop potentially harmful bacteria, and lessen in quality.