Methods of Drying, Storing and Handling Dry Edible Beans

January 14, 2023November 16, 2023 Agric4Profits

Research has shown pinto beans should be stored at temperatures of 40 F or cooler to maintain color and cooking quality. After 10 months of storage, pinto bean cooking times of 16% and 18% moisture beans stored at 20 F were only 1.2 times longer than before storage and at 40 F were 1.7 times longer.

Pin cooking time is the elapsed time from initiation of cooking until the piercing tip of the rod placed in contact with the surface of each bean has penetrated the seeds in the cooker. Faster cooking times are desired.

If beans cannot be kept cool, the moisture content must be low enough to permit storage without deterioration at typical summer temperatures.

The recommended moisture content for beans to minimize the growth of mold is about 13% at 70 F. Pinto beans darken rapidly when exposed to light, so they should be stored in a dark environment.

Median pin cooking times for beans stored for 10 months at specified moisture contents and temperatures. Median cooking time before storage was 18.4 minutes. Shorter cooking times are preferred.

Following good storage management practices, such as measuring the temperature and moisture content of the beans at least every two weeks during fall, spring and summer and monthly during the winter is important.

Whenever more than a 10-degree differential occurs between the average outdoor temperature and the bean temperature during the fall, the beans should be cooled with aeration.

This should continue until the beans are cooled at least to 40 F for short-term storage and about 25 F for long-term storage.

To minimize the potential for mechanical damage, beans should be handled at moisture contents of about 16% or greater and at warm temperatures.

Research shows that the potential for mechanical damage of pinto and navy beans increases at bean moisture contents of about 15% or lower. Research also shows that the potential for mechanical damage of pinto and navy beans increases at lower bean temperatures.

Mechanical damage: cracks in the seed coat of pinto and navy beans at selected moisture contents at a temperature of 75 F.

Mechanical damage: cracks in the seed coat of pinto and navy beans at 16% moisture content and selected temperatures between 10 and 75 F.

Belt conveyors are preferred due to their gentleness in conveying. A bean ladder should be used inside storage bins to reduce impact damage. The speed of auger rotation should be reduced and augers operated “full” to minimize damage.

Elevator legs need to be adapted for handling beans, including reducing the discharge velocity and utilizing a method of gently slowing the beans at the bottom of sprouts.

Natural air drying will work well for drying edible beans during mid-September to mid-October in North Dakota.

Based on average climatic conditions, the beans are expected to dry to about 12% to 14% moisture if the fans are operated continuously.

Shutting fans off during the warmest and driest part of the day will permit drying the beans to about 15% to 16%, but will lengthen the drying time.

Fans should run during the night with higher humidity to permit drying the beans nearer to the desired final bean moisture content.

Refer to equilibrium moisture content tables to estimate the moisture content to which the beans will dry based on air temperature and relative humidity.

Adding supplemental heat reduces the final moisture content of the beans and likely will result in beans dried to a moisture content lower than desired.

Shut fans off during foggy or rainy weather, but do not leave the fan off for more than a couple of days to minimize the potential for bean spoilage.

Minimum recommended airflow rates and estimated drying times for dry edible beans using a natural air drying system from mid-September to mid-October in North Dakota.

The static pressure associated with moving air through pinto and navy beans is equivalent to that of soybeans. Design the drying system using the data for soybeans.

Beans require special care when drying with a high-temperature column dryer. The relative humidity of the drying air should not be lower than about 30%.

Normally, the drying should occur with the air heated less than about 20 degrees above the outdoor air temperature to keep the relative humidity above 30%.

The beans need to be monitored continuously to assure they are not being damaged. The drying process needs to be slow to minimize damage to the beans and will be slow in comparison with drying cereal grain.

Production Contracts

Production contracts are common in the dry bean industry. This section provides a brief overview of key contract provisions that should be reviewed and understood before entering into a production contract.

Understand what you are signing: Reading and understanding contract provisions always is important because they describe the rights and responsibilities of both parties in the agreement.

Considerable differences can occur in contract terms among companies and contract provisions often change through time. Discussing contract provisions with the buyer before signing a contract can prevent misunderstandings and help maintain a strong working relationship.

Production requirements

Most dry bean production contracts specifically require the farmer (seller) to use accepted agronomic production practices and apply only registered crop protection products.

Some contracts also include a list of acceptable cultivars or require the seed be purchased from the company (buyer). Because beans are used as human food, the expectation is that food safety standards and testing will become more stringent in the future.

Stricter food safety requirements likely will lead to contracts including more detailed production provisions.

Act-of-God clause

Some dry bean contracts contain an Act-of-God clause, which releases the farmer (seller) from the terms of the contract due to an act of God, such as hail, drought, flood or disease.

An Act-of-God clause normally only covers the production shortfall below the contracted amount. The farmer (seller) is still expected to deliver the available production from the contracted acres.

The farmer (seller) must notify the company (buyer) as soon as possible when a potential production problem occurs to ensure that this contract provision is enacted. Many contracts require the farmer to provide written notice within 10 days of an event.

Grading and quality standards

The U.S. Department of Agriculture’s Federal Grain Inspection Service standards are the core standards used to trade dry beans. However, some domestic and international end users are beginning to request more detailed grading and quality specifications.

Grading and quality specifications should be clearly listed in the contract. If they are not, be sure to ask the buyer for a copy of the grading and quality standards that will be used.

Delivery period

Production contracts typically require delivery at harvest, during a pre-specified delivery period or on a “buyer’s-call” basis. Harvest delivery refers to delivery directly from the field to the agreed-upon delivery point during the normal harvest period.

This is the most common type of contract in the dry bean industry. Buyers in other crop sectors commonly offer alternative prices for pre-specified delivery windows, such as the first half of October, to better match deliveries with expected shipments.

Buyer’s-call refers to an open-ended delivery schedule in which the company (buyer) will determine the delivery period and schedule deliveries with the farmer (seller) when needed. Buyer’s-call typically requires the farmer to store the contracted production until delivery is requested.

Pricing and payment

Dry bean production contracts typically use a fixed-base price for the contracted production.

Price premiums or discounts can be used to adjust for grade and quality differences, but the specific premium or discount rates normally are not known until the time of delivery.

Payment generally is made a short time after all of the contracted production has been delivered. However, delayed payment or deferred payment options often are available.