Effect of Defatted Wheat Germ Content and Its Particle Size on the Rheological and Textural Properties of the Cookie Dough

The Box-Behnken experimental design and modern instrumental methods were applied to examine the rheological and textural characteristics of the cookie dough, depending on the amount of flour replaced with wheat germ (5, 10 and 15%), different particle sizes of wheat germ (<150, 150-1,000, 800-2,000m) and varying moisture content of the dough (20, 22 and 24%). The results showed that increasing particle size of the wheat germ reduces deformation compliance of the dough. Moisture content had the greatest impact on dough elastic and viscous modulus. Particle size of wheat germ had an impact on resistance to extension and on extensibility of the dough. Wheat germ content up to 15% had no influence on the rheological and textural characteristics of the cookie dough. Practical ApplicationsWheat germ is nutritionally the most valuable part of the grain of wheat. It is a rich source of vitamin E, B vitamins, protein, dietary fiber and minerals (calcium, iron, potassium, magnesium, zinc). Unfortunately, wheat germ is one of the main by-products of milling because of its high oil content. Using defatted wheat germ (by-product of the wheat germ oil removing process), we can nutritionally enrich cookies that are ready-to-eat, have long shelf life and widely consumed food. The present results indicate that the combination of wheat germ content, its particle size and moisture of the dough can be used to improve the nutritional quality of the cookies, without a negative effect on the physical characteristics of the dough.