In his article in the November issue of World Grain, “Wheat flour finds outlet in value-added category,” Jeff Gelski describes value-added wheat flour approaches in the United States, including flour with higher levels of fiber, identifying domestic sources of Neapolitan-style pizza crust flour and improved food safety technology minimizing potential of flour microbial contamination. The purpose of this article is to review basic milling technologies and initiate thoughts on approaches to develop value-added products from grains, pseudo-grains, pulses and seeds.

Cereal grains, pseudo-cereals (non-grasses that are used in much the same way as cereals), pulses and seeds are generally prepared for commercial or wholesale marketing after minimal processing steps, including cleaning to remove non-food material and food unsuitable for consumption, separation of anatomical components, shaping, or size reduction. Some steps such as drying, steam and/or heat treatment are required to provide a stable finished product.

Food manufacturers may use these milled products to manufacture wholesale products for consumer purchase, preparation and consumption or the milled product may be sold direct to the consumer for preparation and consumption. Each of the steps between the production field adds value to the harvested crop.

Functional foods

In the 1980s, the Japanese government created a class of “functional foods” that included additional health benefits beyond those covered by basic nutrition. Functional foods include those minimally processed whole foods along with enriched or enhanced foods that when consumed at a proper level and frequency benefit health by reducing chronic disease risk. Cereal grains, pseudo-cereals, pulses and seeds fit the basic definition of functional foods.

Functional foods cover a variety of foods other than those previously mentioned. Functional foods can be separated into two broad classifications. The first classification — conventional or minimally processed whole foods — are rich in important nutrients like vitamins, minerals, antioxidants, and heart-healthy fats. The second classification includes fortified, enriched, or enhanced foods functional foods fortified with additional ingredients, such as vitamins, minerals, probiotics, or fiber, to increase a food’s health benefits.

Cereal grain, pseudo-cereal, pulses, seeds and their byproducts have a potentially beneficial effect on health when consumed on a regular basis and at certain levels.

Milling technology’s role

Milling technology used in our field has application in many food processes and when combined with other processing methods can offer the opportunity to produce value-added products from a variety of traditional and non-traditional biological materials. The cleaning step used in most of our processes leverages a variety of properties, including particle size, shape, specific density, color, flow property in air, magnetic properties, friability, and solubility. The cleaning step in the most general terms removes unintentional contamination and targets material not suited for processing due to a variety of quality factors. In some cases, the introduction of moisture is essential to making separations in primary, while in others drying may be employed to facilitate additional processing.

The processing steps employed may include application of force such as impact, compression, shear and, when combined, attrition and abrasion, to aid in separation of anatomical parts and/or size reduction. Sifting, purification and air classification also may be used to facilitate separation and particle size control. Additional processing steps may be required to enhance stability and provide final shape. Figure 1 provides an overview of the dry milling process.

Figure 2 shows some of the products from the dry milling processes for various cereal grains. The chaff associated with wheat growth and production is largely left in the field while, in the case of rice, oats and barley, the chaff or hull remains attached and is therefore removed by impact as in oat milling or more aggressive abrasion as in barley milling. The bran of wheat comes off in larger sections as it moves through the break system while that of rice has to be abraded off the brown rice to remove the bran. In the case of corn and sorghum milling, the refined product must have the hull removed and the germ separated to prevent rancidity. Oats must be hulled and the groat steam treated to stabilize the oat product before it can be cut, steamed, and flaked to make an oat flake. All these milling systems address properties of the material to be processed and finished product specifications to determine equipment selection and setting.

These milling technology processes may be used not only for cereal grains, pseudocereals, pulses and seeds but other biological products as well. In addition, such processes may be positioned ahead of chemical and physical separation technologies such as solvent extraction, expellers, and other types of fluid extraction techniques.

In reviewing a YouTube video showing cannabidiol (CBD) oil production, which is an extract of the cannabis plant and utilizing hemp flowers and leaves for its production. The video showed after a brief grind in a large-scale food processor a wide range of particle sizes and, in particular, buds or flowers, which may have a higher oil content than leaves or stems. To access raw material, dried product could be separated into stems, leaves and buds to determine if the anatomical parts had different oil contents. As the ground hemp undergoes solvent extraction, coarse product may retain residual oil depending on thickness and retention time in the extraction chamber. Production rate (time in extractor) may be reduced with smaller, more uniform product increasing batches per day, thereby reducing both fixed and variable costs. 

It seems that recovery could be improved by separating and regrinding coarse raw material to make product more uniform and penetrable for ethanol. To justify further study, the extracted cake should be separated and anatomy (stem, leaf, buds) evaluated for residual oil in the ground fractions. Anticipating some of the larger fractions in any of the anatomical parts will have significantly higher oil content. This relates to lower recovery efficiency increasing both fixed and variable cost, raw material cost and lost profit. The system looks like it could use a miller’s perspective.

A challenge for millers

Here is the challenge: what can you do with your existing product or product line to enhance properties and add value? Is there a favorite food product in your country that could be made more readily accessible to consumers with some processing in your facility? Is there a product from another part of the world you could make and deliver domestically to add value? Are their composite flours you could produce that would have interest in your market? Are ancient grains grown in your region that could experience a rebirth as part of the cultural heritage as Breadfruit is doing in the South Pacific? Perhaps investment in a local cottage industry might allow for testing a development to enhance your value-added product line.

Finally, what can happen looking into byproducts and moving them from the livestock feed area to a value-added nutritional source for either humans or animals? Plant protein sources are becoming more important as a primary protein and nutrient source. Wheat aleurone was commercially available as Leuron (Healthbalance, Uzwil, Switzerland) and has outstanding natural nutritional properties. In the future such products and process will be needed to feed our world.

The extraction of natural bioactive compounds from biological materials and their byproducts will become more important because of medicinal properties and commercial interests in food production. Millers may be the practical specialists that can take into account the nature of the plant matrix to assist with efficient conventional and non-conventional selective extraction.

How will you seek to develop a value-added strategy in your region?

To view Figure 1 and 2 visit World Grain’s February Digital Edition. 

Jeff Gwirtz, a milling industry consultant, is president of JAG Services Inc. He may be reached at [email protected].