Mechanical Seed Coat Damage in Dry Beans and Its Effect on End-use Product Quality

Friday, March 17, 2023

Useful information for dry bean growers and processors to better understand mechanical seed coat damages and ways to prevent it.

With the use of modern equipment in harvest and post-harvest handling of dry beans, the seed coat of beans can be damaged. The damage can result in mild to severe seed coat checks (SCC) and cause split seeds in cooked beans, therefore affecting the quality of end-use products such as canned bean products

The most significant mechanical seed coat damages usually happen during harvest and warehouse cleaning and handling. While a series of post-harvest cleaning methods are used to remove debris and contaminants, it is difficult to separate and remove seeds with SCC. SCC has been a major seed quality concern for commercial bean growers in both organic and conventional systems and it can cause direct economic consequences. According to a personal conversation with the grower relations manager at ADM seed company in Michigan, at the local elevators, over 10% of checked seeds in a dry sample—or over 20% in a soaked sample—is considered unacceptable and a lower price or discount may be provided or even the entire load may get rejected depending on the general seed quality when they arrive.

Harvest survey identified variations in SCC severity level in Michigan dry beans A survey was conducted during the 2021 growing season to investigate the mechanical seed coat damage occurring in Michigan-grown dry beans during harvest. A total of 48 Michigan bean growers participated in the survey. The collected samples were tested for seed coat check severity and evaluated for canning quality at Michigan State University (MSU) and U.S. Department of Agriculture (USDA) Agriculture Research Service (ARS) facilities. The number of bean samples collected in each market class in this survey

The varieties of collected black beans included “Black Beard”, “Specter”, “Zenith”, “Zorro” and “Nimbus”. The varieties of navy beans included “Medalist”, “Bounty” and “Merlin”. The small red beans were all “Viper”. The light red kidney beans included “California Early”, “Big Red” and “Pink Panther”.

Source: msu.edu