Effectiveness of modified 1-hour air-oven moisture methods for determining popcorn moisture

Authors: Brabec, Daniel - Dan; PEREZ-FAJARDO, MAYRA - Kansas State University; DOGAN, HULYA - Kansas State University; Yeater, Kathleen; Maghirang, Elizabeth

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2018
Publication Date: 5/1/2018
Citation: Brabec, D.L., Perez-Fajardo, M., Dogan, H., Yeater, K.M., Maghirang, E.B. 2018. Effectiveness of modified 1-hour air-oven moisture methods for determining popcorn moisture. Applied Engineering in Agriculture. 34(3):617-621. https://doi.org/10.13031/aea.12621.
DOI: https://doi.org/10.13031/aea.12621

Interpretive Summary: Several standard methods are available for measuring grain moisture, but there is not a specific method for popcorn. One of the most common oven-moisture methods specific for whole corn requires a drying time of 72 hours. A faster method which is commonly used for wheat specifies grinding the wheat into a small particles and drying the ground sample for 1 hour. When the faster grind/dry method was applied to popcorn, the grinding of the popcorn damaged the normal screen which is specified for wheat, but when we used a screen with a larger opening the popcorn was ground as expected, but did change the particle sizes produced. To determine whether the accuracy of the moisture measurement has changed with this modification, moisture measurements were compared to standard methods for whole corn. Additionally, a second grinder was evaluated because, as the years pass, new equipment becomes available to try. The new 1-hr method, with the usual grinder and 10 mesh screen, proved to be statistically similar to the 72-hr whole grain method. Also, the second grinder provided statistically similar results when the drying time was reduced from 60 to 50 minutes. These modifications to the standard methods validate that the 1-hr grind/dry method can be used with popcorn to provide moisture measurements that would otherwise take over 72 hours.

Technical Abstract: Two of the most commonly used approved grain moisture air-oven reference methods are the air oven method ASAE S352.2, which requires long heating time (72-h) for unground samples, and the AACC 44-15.02 air-oven method, which dries a ground sample for 1 hr, but there is specific moisture measurement method for popcorn. The objective of this study was to develop an air-oven procedure for popcorn that requires short heating time (1hr or less) based on existing reference method for ground corn (AACC 44-15.02). In the process of procedure development, the effect on oven moisture measurements when utilizing two laboratory mills (Wiley Mini-Mill and Perten 3303 Mill) that were optimized for mesh screen size and mill gap settings. The approved AACC method recommends using a 20-mesh screen fitted to the Wiley Mill. However, it failed with wires breaking during the grinding process, possibly due to the hard nature of popcorn and/or clogging. It was replaced with the 10-mesh screen which produced larger particles size distribution with ~73% greater than 840 µm. The Perten Mill 3303 was set to gap No. 3 which produced ~68% particles that were greater than 840 µm. Additionally, this study evaluated the effectiveness of single-stage moisture measurement with the 14.5% and 16% moisture popcorn samples. The AACC 44-15.02 recommends a two-stage drying method for grain over 13%. But this involves more handling and drying time. Using the proposed procedure, four varieties of popcorn were tested at three different moisture contents (13%, 14.5%, and 16%). The method using the Wiley grinder and 60 min. heating time yielded oven moisture values which were statistically (p<0.05) similar to the approved ASAE S352.2 and AACC 44-15.02 (72-h, whole grain method). The moisture content of ground samples obtained from the Perten 3303 Mill had elevated moisture measurements and bias across the moisture levels when dried for 60 min. A reduction in heating time to 50 min. resulted in Perten mill samples yielding statistically (p<0.05) similar moisture measurements with the reference 72-h, whole grain method.