Dry Beans

Market classes are defined by seed colour, pattern, size, and shape, and they exist because end users need consistency in the finished food. A baked bean requires a bean that holds its skin and shape through canning and looks right in the tin; a black bean is bought for a colour that must not run pale. Classes are therefore kept segregated from the field through to the packer, and admixture of one class into another is a defect in itself, not a matter of taste.

Within a class, size uniformity is specified because it drives even cooking and even appearance. Beans that vary in size cook unevenly, and a can containing some firm and some broken beans is a quality failure whatever the average was.

Dry beans develop a defect that is unusual among commodities: stored warm and humid for long enough, they become progressively resistant to softening on cooking. The beans look sound. They pass visual inspection. They then fail to cook properly, and no amount of extra cooking fully recovers them. The phenomenon is well documented in pulse science and is known as the hard-to-cook defect.

For the trade this has a specific consequence: appearance does not certify cooking quality, and lots destined for canning or retail are bought with regard to their storage history and, where the contract calls for it, cooking tests. It is also why storage conditions for dry beans are a quality matter and not only a spoilage matter — a bean can be perfectly sound and commercially ruined at the same time.

Most dry beans are eaten. Canning is the largest industrial outlet in many developed markets; elsewhere the trade is dominated by packet and loose sales of dry beans cooked at home. Milling into bean flours and ingredient use in food manufacture are smaller but growing outlets, and off-grade lots and screenings find their way into feed.

• Food — canning, most prominently navy beans for baked beans
• Food — packet and bulk dry beans for household cooking
• Food ingredient — bean flours and protein ingredients
• Feed — off-grade lots and screenings
• Seed — retained or certified for planting

Dry beans are large-seeded and brittle when dry, and they crack and split under mechanical stress that a cereal would absorb. Splits and cracked seed coats are graded against and cost the seller directly, so drops, conveyor speeds, and handling frequency all matter. Beans that are too dry break more; beans that are too moist mould and are prone to the hard-to-cook problem, so the storage window is bounded at both ends.

Storage insects, bruchids in particular, are a serious concern in warm climates, and lots destined for food use are protected accordingly. Cool, dry, monitored storage is the standard, and hermetic systems are used where insect pressure is high.