Whole Kernels
Though the name suggests some inverse relationship between whole kernels and BCFM, the whole kernels test conveys different information than the broken corn portion of the BCFM test. Broken corn is defined solely by the size of the material. Whole kernels, as the name implies, is the percent of fully intact kernels in the sample with no pericarp damage or kernel pieces chipped away.
The exterior integrity of the corn kernel is very important for two key reasons. First, it affects water absorption for alkaline cooking and steeping operations. Kernel nicks or pericarp cracks allow water to enter the kernel faster than intact or whole kernels. Too much water uptake during cooking can result in loss of soluble, non-uniform cooking, expensive shutdown time and/or products that do not meet specifications. Some companies pay contracted premiums for corn delivered above a specified level of whole kernels.
Second, intact whole kernels are less susceptible to storage molds and breakage in handling. While hard endosperm lends itself to the preservation of more whole kernels than soft corn, the primary factor in delivering whole kernels is harvesting and handling. This begins with proper combine adjustment, followed by minimizing the severity of kernel impacts due to conveyors and the number of handlings required from the farm field to the end-user. Each subsequent handling will generate additional breakage. Actual amounts of breakage increase exponentially as moisture decreases, drop heights increase and/or a kernel’s velocity at impact increases.2 In addition, harvesting at higher moisture contents (e.g., greater than 25%) will usually lead to soft pericarps and more pericarp damage to corn than when harvesting at lower moisture levels.
Results
- Average U.S. Aggregate whole kernels (85.2%) was higher than 2017/2018 (84.4%), but lower than 2016/2017 (88.2%) and the 5YA (87.8%).
- The average percentage of whole kernels at export in 2018/2019 was lower than at harvest (93.0%). Whole kernels for the export 5YA (87.8%) was also lower than for the harvest 5YA (93.2%). Over the past three years and the 5YA, the percentages of whole kernels have been 5.4 to 7.8 percentage points lower at export than at harvest. This reduction in whole kernels from harvest to export is likely caused by the additional handling required to reach export loading locations.
- The 2018/2019 export samples had a range of 61.4 to 96.2% whole kernels (with a standard deviation of 4.9%), while the 2018 harvest samples had a similar range (66.0 to 98.6%) and standard deviation (3.0%).
- The Pacific Northwest ECA (82.2%) had the lowest average whole kernels compared to the Gulf (86.0%) and Southern Rail (86.2%) ECAs.
- The percentage of 2018/2019 export samples with whole kernels greater than or equal to 90.0% was 15.8%, compared with 14.7% in 2017/2018 and 39.3% in 2016/2017, indicating a much lower percentage of whole kernels in the last two years than in 2016/2017.
- Average whole kernels for contracts loaded as U.S. No. 2 or better was 85.0%, compared with 86.4% for contracts loaded as U.S. No. 3 or better.