As research continues to prove the value of whole grains as a vital part of a healthy diet, health organizations around the world are recommending that people consume whole grains in their daily meals. Since 1999, FDA has allowed manufacturers of foods containing at least 51% whole grains to make a label claim in reference to the foods’ role in reducing the risk of heart disease and cancer. The public is well aware of these health benefits, contributing to the commercial success of whole grain foods. However, there is confusion by consumers about the difference between whole grains and fiber. Whole grains and dietary fiber have been independently recognized to provide the same health benefits, which leads to the confusion. But, there is a difference.
Whole grains typically contain the three layers of the grain: bran, germ and endosperm. The bran is particularly rich in dietary fiber, and many fiber-enriched foods contain only this portion of the kernel. The germ (the kernel’s center) holds most of the vitamins, minerals and fatty acids. In between lies the endosperm, which contains some vitamins and minerals and most of the starch. Thus, whole grains provide fiber and starch, plus protein, antioxidants, fatty acids and phytochemicals, which have been credited with reducing risk of diabetes and heart disease. This article describes the incorporation of the whole grain—endosperm, bran and germ—into extruded products.
Five years ago, whole grain-enriched foods were mostly found in the nutrition bar and diet cereal categories. Today, whole grains are found in breakfast cereals, snack foods, co-extruded products, flatbreads, pasta products and more. While most whole-grain foods are made from flour or meal that contains all three layers of the kernel ground together, a current trend is to use visible whole grains to give a natural look and authentic mouthfeel to the finished product.
Twin screw extrusion gives processors a flexible tool to create a new palette of healthy whole-grain foods that taste great…crispy, expanded products with open cell structure; much different than traditional whole-grain formulations that exhibit heavier texture and denser mouthfeel. A good example of a healthy whole-grain product with high consumer appeal is the multigrain chip. The unique processing technology of the twin screw extruder provides a production environment not possible in the single screw extruder; the intermeshing screws create necessary micro-mixing, combined with intricate regulation of temperature and pressure within individual barrel modules, to successfully produce market-quality multigrain chips that are a hit with consumers. Up to 100% whole-grain formulas are transformed into palatable foods using twin screw technology. This is accomplished by varying the ingredient mix and the processing parameters including temperature, pressure, screw speed and configuration, which are different for each product.
Whole-grain possibilities
Extrusion processing can lead to an array of whole-grain products.
Expanded snacks and breakfast cereals: Using twin screw extrusion, processors can create a variety of healthy expanded snacks and breakfast cereals. Extrusion makes it possible to produce crispy, expanded products with an open cell structure that is much different than traditional whole-grain formulations that exhibit a heavier texture and denser mouthfeel. This is accomplished by varying the ingredient mix and the processing parameters. In this area, improvements in technology are literally reshaping these products. Advances in die and cutter designs are giving processors an entirely new set of templates for creating innovative product shapes. Plus, recent developments in extruder design and control allow more textures and density combinations; for example, light texture with visible inclusions.
Filled snacks: Filled (co-extruded) snacks have crisp cereal shells and soft fillings that delight consumers of all ages. Processors can incorporate whole-grain flour into the cereal shell of sweet or savory coextruded products, adding a healthy benefit to these consumer favorites. Pre-engineered dies let processors create many shapes, such as bars, pillows, nuts, balls and triangles. Fillings range from fruit purée, jelly or creams for sweetened snacks, to cheese and meat for savory products.