Cooking with Dry Beans: Food Science Insights and Strategies from Dr. Guy Crosby

Editor’s Note: Dr. Guy Crosby of America’s Test Kitchen will be speaking with Amy Myrdal Miller, MS, RDN, FAND at the 2016 Academy of Nutrition and Dietetics Food and Nutrition Conference and Expo (FNCE) on Sunday, October 15 from 3:30 to 5:00 p.m. in a session titled “Delicious Plant-Based Dietary Guidance: Food Science and Culinary Strategy.” Amy interviewed Dr. Crosby for this article that provides insights into research from America’s Test Kitchen work on cooking with dry beans.

Guy Crosby, PhD, CFS, is the science editor for America’s Test Kitchen, publisher of Cook’s Illustrated and Cook’s Country magazines. He is co-author of The Science of Good Cooking, published by America’s Test kitchen. Guy is also an adjunct associate professor in the Department of Nutrition at the Harvard School of Public Health where he teaches a course on food science and technology.

AMY: In your book The Science of Good Cooking, you provide information on cooking with dry beans, advice that reduces cooking time and improves texture. This advice is based on extensive research conducted by you and your colleagues at America’s Test Kitchen. Why were you interested in doing research and sharing information on cooking with dry beans?

GUY: Beans are a very healthy food, rich in vitamins, minerals, protein, and a form of starch called resistant starch, which is proven to be very beneficial for gut health. I have been involved with research on resistant starch for almost 20 years so dry beans are a food of great interest to me. Beans contain the highest level of resistant starch. Dry beans are also very inexpensive and readily available, especially for people with limited incomes. Dry beans last a very long time because of their low water content; they are not susceptible to attack by bacteria, mold and fungi. Thus, dry beans offer a source of healthy food that is cheap, readily available, and can be stored for years without food safety problems.

AMY: I was intrigued to read in The Science of Good Cooking that instead of soaking dry beans prior to cooking, you recommend brining the beans. This is advice I’d never seen before. Many sources recommend not putting salt in the soaking or cooking water, saying that doing so will cause the beans to not fully soften. Can you explain the brining process and how brining reduces cooking time and improves texture?

GUY: The slow step in cooking dry beans is absorption of water into the beans to turn them soft, as well as gelatinize of the starch that must be cooked in order to be digestible. Water can only be absorbed into the beans through a tiny opening called the micropyle, so the process is quite slow. Soaking beans in water for many hours reduces cooking time. However, in a pot of beans some beans may cook faster than others. This can lead to some beans bursting their skins, while other beans may not be cooked enough to be soft and creamy inside.

Brining beans involves the same process as soaking in plain water except the brine contains a low concentration of salt (sodium chloride). During brining the sodium ions slowly exchange with calcium ions that are part of a very large molecule called pectin. Pectin strengthens the cell walls in the beans, and calcium strengthens pectin. So natural pectin can produce skins on the outside of dry beans that are difficult to soften and expand, and can eventually burst when the inside of the beans become over-cooked. Exchanging sodium for calcium ions during brining weakens the pectin so the skins become more flexible and can expand without bursting as the interiors to cook to a soft creamy interior.

Thus, brining accomplishes two things: Brining provides water to soften the beans and reduce cooking time, while simultaneously producing beans that do not burst while cooking to the desired soft, creamy texture. Surprisingly, during brining very little salt is absorbed by the beans. Laboratory tests have shown that beans brined for many hours absorb only 52 milligrams of sodium per 3 ounces of brined beans.

AMY: This is fascinating research. I’m especially pleased to hear that brined beans absorb so little sodium.

You also recommend cooking beans in an alkaline cooking environment. What do you mean by “alkaline environment” and what tips do you have for home cooks related to this advice?

GUY: An alkaline environment for cooking dry beans is created by adding a tiny amount of baking soda (sodium bicarbonate) to the cooking water. An alkaline environment means the water has a pH slightly above neutral pH, which is pH 7. The addition of baking soda to the cooking water does two things: It adds sodium ions that weaken the pectin as explained above, and more importantly, an alkaline environment causes the pectin molecules to break down into smaller molecules that greatly weakens the pectin causing the beans to soften much more rapidly. Beans cooked with a tiny amount of baking soda (about one teaspoon per cup of dry beans) added to the cooking water cook in about half the time as beans cooked without.

AMY: The 2015-2020 Dietary Guidelines for Americans recommend we eat 1 ½ cups of legumes (beans and peas) each week (at the 2,000 calorie level), but few Americans are reaching this goal. What other advice do you have for home cooks who want to cook more often with dry beans to enhance their family’s legume intake?

cook-with-beans-v3-small-for-webGUY: Since dry beans can take more attention to cook just right, it turns out that baking beans in the oven provides much more control compared with cooking on the stovetop. Beans cooked in the oven are exposed to more consistent milder heat producing beans that are more consistently cooked with creamy soft interiors and tender intact skins. Also, since beans physically absorb water as they soak and cook, adding water-soluble flavoring ingredients to the water (or brine) increases the flavor of the beans. Thus crushed garlic, onion, thyme, mustard, rosemary, sugar, molasses, and bay leaves added to the soaking and/or cooking water will add flavor to beans.

AMY: This is wonderful advice. In fact, we love this so much we’re including a wonderful Classic Baked Beans recipe as our Recipe of the Month for September. It’s a comforting supper dish for cooler fall nights. Speaking of cooking beans on cool fall nights, when you cook beans at home what equipment do you use?

GUY: For beans that require a long time to cook (i.e., larger dry beans like Great Northern, kidney, or navy) I cook the beans in the oven in a heavy Dutch oven. The heavy Dutch oven absorbs and distributes heat slowly and evenly and results in evenly cooked beans.

AMY:  We know Americans, on average, eat 21% of meals away from home, many of them in restaurants. What’s the best bean dish you’ve ever eaten in a restaurant?

GUY: I would have to say roasted chicken or lamb (and sometimes roasted whole fish) served on top of seasoned cannellini beans. The seasoning complements the meat, such as rosemary with lamb or sage with chicken. The beans offer a flavorful, healthy alternative to pasta or rice, especially when cooked with extra virgin olive oil. When I see one of these on the menu I usually order.

AMY: Well now you’re got me craving Grilled Shrimp with Rosemary White Beans. Now I know what I’ll make for dinner tonight! What are your favorite bean recipes to make at home?

GUY: I have a number of favorite bean dishes such as new England-style baked beans (both navy and kidney style beans), baked cannellini beans to accompany meat, and a number of soups with cannellini beans, sausage and kale, as well as black bean soup, and Tuscan bean stew.  I love cooking dry beans and really can’t boil it down to a single recipe. They’re all great!

AMY: Guy, thanks for these amazing insights. We appreciate respect for science and your love of beans!