Extrusion packs more protein into snacks.

Corn puffs, cheese curls, crispy breakfast cereals and other crunchy puffed foods may soon offer up to seven times more protein. That's if they're made with protein-rich whey, left over after cheesemaking.

USDA-ARS technologists have developed an extrusion-based technique for which they are seeking a patent for this snack application for whey protein. The new snacks could help meet the demands of health-conscious consumers. The process already has drawn the interest of food companies.

Using whey enables the researchers to increase protein in expanded snacks, such as breakfast cereals, corn puffs, cheese curls and energy bars, from the traditional average of about 2% to 5%, to 35%.

Most crunchy snacks are made from high-starch products such as corn flour. An extruder cooks the starch as the equipment's screws mix and push it through the machine to form the snack food. The crunchiness of the snack is determined by its moisture content and temperature as it leaves the extruder. The ARS scientists developed moisture and temperature specifications for the processor so that adding whey doesn't interfere with the taste, color or crunchiness of food products.

It's the goal of some ARS scientists to develop thermal and non-thermal extrusion-based processes that alter the structures of whey proteins and which create specialized texturized ingredients that have unique composite matrices that can help improve product quality. Part of their research also involves developing process protocols for texturizing whey proteins through non-extrusion shear processes, such as by microparticulation. Their aim is to develop new products.

Changes in the texture of whey protein concentrates and isolates, and lactalbumin, alone or in combination with starches and polysaccharides, can be induced through cold extrusion and microparticulation processing. In their research, the scientists determine cold extrusion process parameters that affect structure and function relative to texturization of whey proteins. They evaluate the properties of the shear-texturized proteins, such as elasticity, gelling strength, expansion, foaming and porosity, along with the rheology and network structure shear-induced viscosity changes that result from changes in protein structure.

The cold-extruded and microparticulated proteins may be used alone. Or they can be used to create conjugate gels which will be linked with carbohydrates and other polymers to create functionalized matrices that can be incorporated into foods such as yogurt and meat extenders.

Further information. Charles Onwulata, USDA-ARS Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038; phone: [phone]; fax: [phone]; email: [e-mail].