88C-6 |
Influence of fat on the expansion of glassy amylopectin extrudates by microwave heating |
C. I. MORARU1, V. Ernoult2, and J. L. Kokini1. (1) Dept. of Food Science/Center for Advanced Food Technology, Rutgers, The State Univ. of New Jersey, 65 Dudley Rd., New Brunswick, NJ 08901, (2) ENSA-INRA, 2 place viala, Montpellier cedex 1, 34060, France It has become common practice in the food industry to manufacture half-products which can be further expanded into so-called third generation snacks. The half-products are next expanded by baking, deep fat frying or, recently, by microwave heating. The use of microwave heating brings the advantage of obtaining products with a smaller fat content than those obtained by other methods. The effect of two fats with different melting points on the microwave expansion of extruded glassy amylopectin pellets was studied. Glassy, unexpanded pellets were obtained by extruding amylopectin mixed with increasing concentrations of hydrogenated, high melting point soybean fat and canola oil. The pellets were equilibrated at different water activities and then expanded by microwave heating. The volumetric changes, microstructure and texture of the expanded products were analyzed in order to characterize the expanded products. The addition of solid fat contributed greatly to the degree of expansion, the microstructure and the texture of the product. The fat crystals resulted in a higher number of uniform sized cells, with thin walls. The optimum solid fat content was found to range between 5 and 8%. The addition of liquid fat had, on the contrary, a negative effect on the expansion properties of the pellets. The samples that contained liquid fat expanded less than the amylopectin samples without fat and showed a coarse microstructure. The findings of this work could be used as valuable tools in the design of microwavable snacks with a moderate fat content.
Session 88C, Food Engineering: Physical and Chemical Properties
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