Due to their exceptional nutritional value, common dried beans are an important food worldwide. The industry has undergone wide production distribution expansions from its origins in South and Central America. In North America, Native Americans grew beans, which the settlers adopted later, and the American bean production started to boom by the end of the 19th century. Beans are popular because they are an exceptional source of vitamins, minerals, proteins, and carbohydrates, but they are inedible in their raw state because they contain various anti-nutritional factors and have a firm texture.

Commercial processing and traditional cooking methods can greatly reduce or destroy the anti-nutritional factors, softening the beans and turning them into nutritious and safe food. Distribution and processing factors can influence the quality of beans, including cleaning/grading, washing, soaking, blanching, thermal processing, filling and can size, and brine and pack styles.

Dried Beans: Post-Harvesting Handling and Storage

Unless kept cool, harvested green dried beans temperature could increase, resulting in spoilage. Postharvest and processing facilities must provide adequate shade and ventilation. They should be stored short-term at around 12% moisture or long-term at around 8-9%. To avoid migration of moisture to the cowpea, stored beans shouldn’t be kept on the bare floor but in steel drums or tins, silos, polythene bags, or rumbus. Also, dried beans need to be conveyed a gentle manner to keep their integrity, as damaged or broken beans can encourage insect infestation. To starve any insects of oxygen, the storage structures must be airtight and cleaned adequately for storage.

After harvesting, manufacturers need to remove the seeds from the surrounding plant material through a process called threshing. Threshing should be done when the beans are completely dry and when humidity is low. To protect the beans from dirt, damage, and from scattering, threshing should be done on a threshing rack.

To avoid molding during storage, threshed beans should be dried further on wire mesh trays, plastic sheets, or mats raised on a platform.

  • Minimum requirements for dry beans

In dried bean distribution and processing, the dried grains need to be wholesome, clean, well-filled, and uniform in shape, size, and color. They should also be clean from substances that would make them unfit for human consumption or processing. Dried beans should be clean from discoloration, obnoxious smells, and abnormal flavors, and they should not be musty. They should be cleaned of microorganisms or substances that originate from them (e.g., fungi or other substances) in amounts that may pose a hazard to human health.

  • Dried bean packaging

Dried beans should be packed in containers that will safeguard the technological, nutritional, and hygienic qualities of the product. The packages should also be sound, clean, and free from fungal infestation and insects, while the packaging material must be securely closed and sealed and of food-grade quality. Of course, each package needs to contain dried beans of the same type and grade designation.

The recent advancement of pesticide-free hermetic storage for dry commodities is now used in more than 80 countries across the world. It is crucial in semi-tropical and tropical areas due to high temperatures and humidity, while flexible plastic storage structures have been applied to long-term bean storage. Molds grow exponentially at a humidity level of above 65%, while insects multiply most quickly at high temperatures (30°C and higher). Mold must be prevented from growing because it produces mycotoxins, and lack of moisture and lack of oxygen inhibits its growth.

Canned Beans: Standards of Quality

The US standards for grades of canned beans have been established by the USDA-AMS (US Department of Agriculture, Agricultural Marketing Service). For canned beans packed in sweetened sauce, tomato sauce, or brine, products receiving grade A quality must score at least 90 or higher on a 100-point scale. The absence of defects and character weighed are worth 40 points each, and the color weighed is worth 20 points.

The canned bean product must have good character and flavor, be virtually without defects, have a good consistency (if packed in sauce), and have similar varietal characteristics.

  • Quality evaluation of canned beans

Bean quality can refer to the nutritional, chemical, and physical quality, as well as sensory attributes of the product. Nutritional and chemical measurements performed include oligosaccharides and monosaccharides, resistant and total starch, flavor volatiles, and proximate analysis. As for sensory attributes, they include factors like bean color, size, splits, and degree of packing. Also, it’s important that the processed beans are stored at least two weeks before quality evaluation.

Importance of Cleanliness and Eliminating Breakage in Bean Distribution

For short-term or long-term storage, dry beans are conveyed to storage silos prior to cleaning. The beans delivered through a tubular cable and disc conveyor system are exposed to minimum risk of breakage and contamination (minimizing the seed coat damage is particularly important when conveying dry beans). Minimizing seed coat splitting and checking during all stages of the physical distribution of dried beans is essential because seed coat damage is cumulative during each stage. Dried bean damage is most often associated with dropping and shattering during conveyor transfers. Poorly designed bucket lifts and augers are detrimental and result in damaged seed coats. Tubular drag systems are superior to other conveyor system designs in which individual beans are dynamic, resulting in bean-to-conveyor and bean-to-bean abrasion.

Bean dropping has the most profound effect on bean damage – dumping into free-standing piles or filling into bins and silos are both situations where seed coat damage may occur. Maintaining minimum drop distances and establishing a continuous flow from the truck to the bean pile is recommended, as well as controlling the length of the drop into the bin, to control seed coat damage.

Furthermore, moisture content control of dried beans is crucial for stability in bean storage systems. Adverse distribution and storage conditions could induce bean hydration defects and decrease nutrient bioavailability and seed digestibility, leading to defects known as HTC (hard-to-cook), hard-shell, and bin burn phenomena. Therefore, improved utilization of dried beans can be maximized through proper understanding of the control and impact of post-harvest distribution, storage, and packaging.

  • Addressing the challenge of material breakage

Many food processing plants rely on conveyor systems to distribute fragile foods within their facilities. In the case of dried beans, seed coat damage leads to wasted materials that can affect a plant’s bottom line. Therefore, one of the most critical challenges that needs to be addressed is finding a way to distribute dried beans through all the processing stages with a high level of product safety and minimized seed coat damage and breakage.

Cablevey has created a one-of-a-kind tubular drag system that uses cables and discs to gently move various materials (e.g., delicate, small, and powdered materials). It can move dried beans without stress, friction, battering, or bumping, minimizing bean breakage and seed coat damage. Cablevey’s system enhances cleanliness, offers increased flexibility, and is easy to maintain, which makes it the best solution to meet the requirements of dried bean processing plants. Dried bean manufacturers can’t rely on bucket, pneumatic, or belt conveyors to distribute dried beans throughout their facilities because of dried beans’ physical properties. Also, keeping them contaminant-free during conveying can also be challenging with these systems. Tubular cable and disc conveyors are enclosed, which prevents foreign particles from getting into the stream.

Cablevey conveyors can be installed in vertical, horizontal, and curved configurations to remove the need to re-engineer processes and plants. Furthermore, tubular cable and disc conveyors reduce power requirements significantly – traditional conveyors have maximum motor sizes of up to 50 amps. In comparison, our largest system uses a maximum motor size of 7.5 horsepower! Our engineering team can design a conveyor suited to move any type of product, ingredient, or finished product while reducing equipment downtime and maintenance and preserving product integrity.

Dry bean contamination and damage must be minimized through the use of proper handling practices, and the established standards for food handling are important for sanitary control. The use of good manufacturing practices, good agricultural practices, and a range of advanced food safety and food quality standards are applied in dried bean handling (such as SQF, HACCP, and ISO 9000).

From lima beans and black beans to pinto beans and kidney beans, when maintaining quality in dried bean processing and distribution, food processing plants should have a set of policies and principles regarding dry bean handling as well as the right technology to support them.

Cablevey Conveyors experts understand the bean market grade standards, the shelf life of the final product, and that proper handling and gentle handling means the difference between profit and loss in dry beans production. We know the bean’s life cycle and that beans require careful handling, processing, and moving to ensure their integrity. We are a leading worldwide tubular drag conveyor manufacturer with almost 50 years of experience and clients located in more than 65 countries.