Waxy hull-less barley (WHB) is rich in soluble fiber and low in fat. These characteristics make it a nutritionally valuable ingredient for food products. Research has shown that the soluble fiber, -glucan, reduces cholesterol and lowers blood glucose and insulin response following a meal. Producers and processors need information on the storage requirements of the grain, raw materials, and products made from WHB. Our research has included development of extruded snack products and evaluation of the storage stability of WHB grain, flours, flakes, and extruded snack products.

Extruded Snack Products

Four treatments of WHB cv. Merlin were produced by milling, pearling, and sieving: wholemeal flour (WF), pearled ground flour (PG) , the PG sieved to make a high fiber flour (HPG), and a low fiber flour (LPG). These were extruded at the Northern Crops Institute to produce an expanded product similar to a corn puff. Pearling removed 56% of the insoluble fiber and 66% of the lipid, both components that can reduce expansion during extrusion. A small amount of the soluble fiber (14%) also was removed. Chemical analyses confirmed that the HPG had 1.5 times the soluble fiber as the WF and almost twice as much as the LPG.

The LPG had the greatest expansion (similar to a corn puff) and required the least force to break. The HPG had the least expansion (though it did expand some) and required the greatest force to break. Since the major difference between the PG and HPG is an increase in soluble fiber content, it appears that this component plays an important role in the appearance and texture of these extruded products.

A trained sensory panel liked the LPG snack the best, describing it as the whitest, most crisp, and least hard or tough. Adhesiveness scores were slightly lower than the midpoint, suggesting that all of the snacks adhered slightly to the teeth while chewing. While the barley flavor was on the intense end of the scale, off-flavor was described as extremely mild or nonexistent. The PG snack also rated favorable with the panel.

Snack products stored under high temperature conditions to simulate one year of storage were liked for flavor as well or better than when tested prior to storage. Chemical tests for products of lipid oxidation indicated slight increases, but not enough to effect flavor components detrimentally. An increase in hardness was detected that could be controlled with better packaging.

Storage of Flours and Flakes

An increase in lipid oxidation products was observed in the flours and steam-rolled flakes stored under high temperature conditions. The least change was observed in the flakes that were heat processed. The observed changes in most of the flours were not very great when compared to the pearlings that have significantly higher lipid content. This suggests that flour made from WHB would not require special storage conditions. Pearling increased the stability of the flours and steam rolling improved stability of a whole grain product.

Grain Storage

Three waxy hull-less cultivars were grown in strips along with Robust in three North Dakota environments. Grain samples were stored at two temperatures, 4°C. At this temperature, the samples at 13% moisture had only slightly more lipid oxidation than the samples at 10% moisture. As expected, lipid oxidation increased at 25°C, especially in samples stored at 13% moisture. The Robust samples tended to have higher levels of lipid oxidation products than the WHB samples prior to storage. During storage, higher levels of lipid oxidation products were found in the WHB samples when compared to Robust. This difference was greatest in the samples stored at 25°C and 13% moisture. A second year of storage is being conducted to confirm these observations, but it appears that it will be important to store WHB at a reasonable moisture level, certainly less than 13%.

We would like to thank Dr. Richard Horsley and his research group for providing the grain samples used in the grain storage studies.

Publications

Fastnaught, C.E., Berglund, P.T., Holm, E.T. and Fox, G.J. 1996. Genetic and environmental variation in -glucan content and quality parameters of barley for food. Crop Science (accepted for publication in July-Aug. Vol. 36, no. 4).