Extrusion and Thermal Processability of Waxy Wheat

Ryan Joseph Kowalski

Starch within wheat flour is composed of both linear glucose polymers, known as amylose, and branched glucose chains, known as amylopectin. While most wheat starch is composed of approximately 23-28% amylose, waxy wheat contains no amylose, and is composed entirely of amylopectin. The difference in the chemical structure creates a variety of different processing characteristics for waxy wheat flour. To characterize the behavior of waxy wheat flour and its potential for processing, it was first characterized through rheological and thermal analysis, and then run through an extruder to observe its potential in puffed products. Extruders harness the potential of thermal and rheological properties of flours to pressurize and melt flour with the use of rotating screws. Extruders then force melted flour through a formed opening, causing melted flour to shape, and expand into cereals and snack foods. Multiple varieties of waxy wheat were extruded in order to determine which varieties of waxy wheat may have the most potential in extruded food products. Overall, waxy wheat flour was able to expand in extrusion the same amount as non-waxy wheat flour with significantly lower mechanical energy inputs, offering the ability to produce snack foods with lower operational costs. The strong potential of waxy wheat for use in extruded products was then analyzed further through the novel extrusion technology of carbon dioxide assisted extrusion. Carbon dioxide extrusion has been shown to puff products with carbon dioxide, as opposed to steam, leading to more regular food structures. Based on the thermal and rheological properties of waxy wheat, it was shown that it may offer a potential solution to the very narrow window of flours that currently work with this technology. Lastly, waxy wheat was used as a medium to discover new methods of how an extruder screw can be designed. This was done using a modeling technique known as multi-objective evolutionary algorithms. Through utilization of this technique, a successful predictor of which extruder screw profile is needed for a specified product was created. By using the explored technique, food manufacturers may be able to more rapidly design newer and healthier food products for consumers.

Extrusion and Thermal Processability of Waxy Wheat

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