The products are used by foodservice outlets or used by other food processors in entrÃ©e or component meals. They can be breaded and battered like their natural counterparts. They save the user the additional processing step of rehydration, unlike previous textured vegetable products. “The product is also fully cooked as it exits the cooling die,” says Borders. “That’s adds a convenience for the user.”Two screws better than one
Twin-screw extruders have displaced their single screw counterparts in most food operations. Single-screw extruders have been relegated largely to animal feed manufacture in recent years, though some use in human food products continues.
Pre-conditioning the raw material mix for extruded product dates back to the 1950s. “But learning how to utilize pre-conditioning has really advanced in recent years,” explains Baldwin.
Extruder size is generally given in terms of a length-to-diameter (LD) ratio; that is, the length of the overall barrel to the screw diameter. “We have been able to reduce the length of the extruder barrel and thus reduce hardware requirements,” says Baldwin.
“We also work more with thermal energy than mechanical energy,” Baldwin continues. That’s a plus with energy consumption an ongoing issue in the plant. “It’s more economical to process with thermal energy than with mechanical energy. If you can do more with steam during pre-conditioning, you can do more cooking with less horsepower.”
Clextral Inc. (www.clextralgroup.com), Tampa, Fla., was the first to adapt the twin-screw extrusion concept to food applications. The equipment maker’s emphasis today is on the modular concept, simplifying changeover and removal of screws, barrels and dies. New designs allow screw elements to slide onto splined shafts. They also are more hygienic and operate at higher speeds. These practical design improvements also have made the twin-screw extruder more welcome on the processing floor.
“Our twin-screw extruders today allow quick change of screws and easy cleaning capability,” notes Laurent Garcia, sales manager of Clextral. “With hydraulic opening, you can access the screws within five minutes for maintenance and quick changeover. You also get a good view of what is happening in the machine. You can see where the starch is gelatinized.”
Better temperature control and auto-mation capabilities not only have improved product quality and consistency, they also add to the flexibility and versatility of today’s machines. “You can adapt an extruder platform to new applications. Keep in place your main equipment and add auxiliary equipment for new products,” says Garcia.
Twin-screw extrusion offers an infinite range of possibilities, inviting innovation in mixtures of fillings and colors and a wide variety of tastes and textures.
“We were the first to develop flat crisp bread, coextruded with a sugar filling inside,” notes Garcia. “You can add chocolate, marmalade and other fruit-taste fillings.”
Snacks and RTE cereals may be the most conspicuous areas of extrusion application, but Garcia likes the possibilities opened in the nutrition area, particularly for low-carb products and texturized proteins.Snack power
The extruder’s adaptability to such a wide range of raw materials has opened a large window of opportunity in snacks. Snack pellets have had more significant impact in the marketplace in Asia and the Mideast than they have in the U.S.
Economics explain part of their popularity. Pellet products begin with blended ingredients that emerge from a cooking extruder as a dense pellet. Their moisture content is reduced.
Shelf-stable pellets are passed to the processor, who prepares the final product by “puffing” it with hot oil, microwave heat, hot air or other method. In some markets, the final preparation is left to the consumer.
|What’s the next likely trend in extruded products?
Extruded snacks with reduced carbohydrate content are a no-brainer and already in the product mix. Extruded soy proteins will likely spread into more simulations of meat-based products.
Frito-Lay, the snack giant from Plano, Texas, owns a gold mine in its Cheetos line of extruded snacks. The company has developed its own proprietary extrusion technology, company sources say. Latest is an extruder that produces a spiral Cheeto.
The company’s most recent addition to the line is Baked Cheetos, a snack that qualifies as a healthier option with the package display of the PepsiCo Smart Spot, a marketing item Pepsico is adding to the packaging of all its “healthier” products.
The current quality of today's meat analogues offers tremendous opportunity to spread good nutrition in good-tasting forms to developing nations. But the current generation of high-quality analogues carries a cost that may relegate the products to the realm of higher ticket value-added products for some time. Still, the promise of solving human hunger continues to make extrusion technology a potential savior as well as a profit maker.
So sophisticated has extrusion technology become that its targets today are analogues nearly indistinguishable from the real McCoy.
“We have done work on extruded cereal flakes and have seen interesting development in that area,” says Doug Baldwin of Wenger Manufacturing Inc., a Kansas City, Mo., manufacturer of extruders. “Processors are trying to develop an extruded flake to match the appearance, quality and texture of a processed flake.”
Add that to a chicken breast not even the Colonel could tell from the original, and we have seen how far extruder technology has come.