Neil Doty, Northern Crops Institute

Human food and animal feed industries have become focused on reducing microbiological hazards originating from agricultural commodities. Flour and meal products derived from grain, such as corn, can be contaminated with microbiological hazards from the commodity itself; animal, bird, and insect contamination; transport equipment; storage facilities; processing equipment; and packaging materials.

Food and feed processors are charged with ensuring all potential microbiological hazards are identified and mitigated as mandated by the 2011 FDA Food Safety Food Modernization Act. Many food processors have adopted the attitude that seeds, nuts, and grain are not safe to use for human food without a microbe reduction treatment. Several treatment technologies involve the use of heat to achieve a microbe reduction treatment for seeds and grains.

A combination of increased corn acres in North Dakota along with increased demand for whole grain flour as a superior food ingredient for a variety of food products may provide an opportunity for the development and operation of a food-grade corn mill in North Dakota. New food-grade corn mill operators in North Dakota will be faced with the decision whether to incorporate heat treatment technologies to corn prior to milling in order to mitigate the risk of microbial contamination of milled corn flour.

The objectives of this study were twofold: 1) to select a potentially effective heat treatment procedure on corn kernels that result in milled whole grain corn flour with minimal effect on starch viscosity characteristics and 2) to determine if a heat treatment on corn kernels affects the quality of whole grain corn flour baked goods, snack food, and pasta products.
The Northern Crops Institute (NCI), Fargo, ND, evaluated samples using the Rapid Visco Analyser® technology to analyze heat and moisture treated corn kernels to select an effective heating time and temperature that had a minimal effect upon corn starch characteristics. A Fitzmill® hammermill was used to produce whole grain corn flour.

Three corn-based baked goods, cornbread muffins, corn pancakes, and Brazilian corn cookies, were produced and evaluated at the NCI bakery laboratory to determine the effect of a whole grain corn flour heat treatment on product quality. 100% whole grain corn extruded snack puffs (also known as snack collettes) were produced at the NCI twin screw extrusion laboratory. 100% whole grain corn, gluten free pasta was produced at the NCI pasta pilot production laboratory to evaluated to determine the effect of a whole grain corn flour heat treatment on pasta quality.

Heat treated whole corn flour can be utilized to produce corn flour expanded snack collettes with a milder flavor profile and a more appealing texture. Heat treated corn flour does not exhibit detrimental effects on the preparation of corn flour expanded snack collettes. Unheated whole corn flour is superior to heat treated whole corn flour as the primary ingredient in whole corn, gluten free penne pasta. Heat treated corn flour penne pasta had nearly double the cooking loss of unheated corn flour penne pasta. Heat treated corn flour penne pasta had only ¾ of the el dente firmness of unheated corn flour penne pasta.

In industry practice, high temperature, short time, high humidity heat treatments are being used to sterilize nuts, seeds, and grains. Heat treatments on corn kernels can be utilized to reduce the incidence of microbiological risk and also improve food product characteristics, primarily in extruded snack foods and baked goods. Conversely, heat treated corn flour yielded pasta products with unacceptable cooking losses and inferior firmness scores.
A North Dakota-based corn milling entity should fully evaluate adding a microbiological kill step to corn to determine effectiveness of microbiological mitigation and corn flour product quality prior to implementation.