Dear Dr. Blonz: I live by myself and find it difficult to use up an entire loaf of bread before it dries out and becomes stale. I have tried storing bread in the refrigerator, but it never tastes the same. What is it about refrigeration that ruins bread? — J.W., Las Vegas

Dear J.W.: Bread turns stale as its starches undergo changes in structure. Although stale bread has a dried-out appearance, a loss of moisture is not the complete explanation — a loaf will even turn stale in a well-sealed, never-opened package. Temperature, it turns out, is a key.

There are two main types of starch, or carbohydrate, in bread. Over time, each will change from a random to a more rigid arrangement. The first starches set up as a freshly baked loaf of bread cools to room temperature. If you have ever attempted to cut into a loaf right out of the oven, you’ll recall that doughy texture before the first starch sets up. The setting up of the second starch takes about a week. As that second starch changes, the texture of the bread shifts from soft to hard — or as we call it, stale.

While refrigeration extends the shelf life of many foods, the second starch tends to set up faster at refrigerator temperatures. Your bread could turn stale in about a day. Refrigeration is not recommended for the storage of any raised bread product.

It’s unfortunate that sandwich vendors tend to store their premade sandwiches under refrigeration, but it does make sense: A slight staling of the bread is the price to keep the sandwich’s contents fresh. If buying a premade sandwich, try to get one that was made earlier that day.

As for the bread you keep at home, one solution is to look for breads that use preservatives called emulsifiers. They can slow down the setting up of starch and effectively extend shelf life. The most common emulsifiers used in bread, the monoglycerides and diglycerides, are effective yet harmless additives.

Freezing may be the ideal solution for your issue. Freezer temperatures are cold enough to keep the second starch from setting. Consider splitting your loaf and storing half in the freezer. However you decide to store your bread, make sure the package is always well sealed.

Dear Dr Blonz: Carrots in the refrigerator get soft and flexible after a few days, and eventually, they shrivel. When are they no longer safe to eat? — B.B., Chicago

Dear B.B.: Carrots are a root crop, providing the route by which the water from the soil is taken up and transported to the rest of the plant. The fibrous part of the carrot contains flexible little compartments that hold water until needed by the rest of the plant above.

When the carrot sits, exposed to the air, the water evaporates. Over a matter of days, this will result in the more flexible vegetable you described. Eventually, the carrot will wilt and rot. To retain moisture and firmness, carrots should first be washed, the excess water shaken off and then placed in a plastic bag in the refrigerator crisper. Also, if you buy carrots with greens attached, remove them after purchase, as they tend to draw the water out of the carrot.

Carrots can be considered safe to eat as long as they’re not discolored, overly shriveled or slimy in feel. If a carrot has only lost some of its firmness, it can often be brought back with a soak in ice water.

Ed Blonz, Ph.D., is a nutrition scientist and an assistant clinical professor at the University of California, San Francisco. He is the author of the digital book “The Wellness Supermarket Buying Guide” (2012), which is also available as a free digital resource at blonz.com/guide.


Featured video

Blue Coast Juicy Seafood takes over the space that housed Mimi's Cafe on 71st Street.

Read Scott Cherry's review: Blue Coast Juicy Seafood lives up to its unusual name