Horneous (Hard) Endosperm
The horneous (hard) endosperm test measures the percent of horneous or hard endosperm out of the total endosperm in a kernel, with a potential value from 70 to 100%. The greater the amount of horneous endosperm relative to soft endosperm, the harder the corn kernel is said to be. The degree of hardness is important to the type of intended processing. Hard corn is needed to produce high yields of large-flaking grits in dry milling. Medium-high to medium hardness is desired for alkaline cooking. Moderate to soft hardness is used for wet milling and livestock feeding.
Hardness has been correlated with breakage susceptibility, feed utilization/efficiency and starch digestibility. As a test of overall hardness, there is no good or bad value for horneous endosperm; there is only a preference by different end users for particular ranges. Many dry millers and alkaline cookers would like greater than 90% horneous endosperm, while wet millers and feeders would typically prefer values between 70 and 85%. However, there are certainly exceptions in user preference.
- Average U.S. Aggregate horneous endosperm (81%) was higher than 2016/2017 (79%), slightly higher than 2015/2016 (80%) and slightly lower than 5YA (82%).
- Average horneous endosperm for 2017/2018, 2016/2017, 2015/2016 and export 5YA were within ±1% of the average horneous endosperm for 2017, 2016, 2015 and 5YA at harvest, respectively.
- The 2017/2018 export samples for horneous endosperm had a smaller range (75 to 90%) and standard deviation (2%) than the 2017 harvest samples’ range (71 to 92%) and standard deviation (4%). This same pattern of increased uniformity for export samples compared with harvest samples occurred in 2016/2017, 2015/2016 and 5YA as well.
- Average horneous endosperm among all ECAs was within 1, 1, 0 and 2 percentage points of each other for 2017/2018, 2016/2017, 2015/2016 and 5YA, respectively.
- Of the 2017/2018 export samples, 72.0% had at least 80% horneous endosperm, in contrast to 25% in 2016/2017 and 55% in 2015/2016. This indicates a higher percentage of the 2017/2018 samples contained high amounts of horneous endosperm than in the two previous years.
- Average horneous endosperm for contracts loaded as U.S. No. 2 o/b was 81% and for contracts loaded as U.S. No. 3 o/b was 82%.