The fast-growing population and the depletion of food sources do not allow throwing away such a large amount of food. The amount of food lost and by-products that occur along the supply chain of processed products is around 46% for some products. In our country, as well as worldwide, during the processing of wheat, apples, and beer production, a significant amount of by-products remains, which are rich in protein, dietary fibre, and minerals. The large presence of cookies in the daily meal structure enables the replacement of their raw materials with nutritionally valuable components, allowing them to be successfully introduced into the human diet. The task of this work was to examine the influence of replacing a part of wheat flour with extruded flour enriched with the addition of wheat germ, beer pomace and apple pomace on the characteristics of cookies (nutritional, sensory, microbiological). Extrudates of corn grits with the addition of wheat germ, beer pomace and apple pomace in proportions of 15, 30 and 45%, milled to obtain three fractions with different particle sizes (<250 μm, 250 – 1000 μm and 1000 – 2000 μm) were used as a substitute for wheat flour in quantities of 5, 10 and 15%. The addition of wheat germ and beer pomace extrudates significantly increased the protein content in cookie samples, and all three by-products caused an increase in the content of minerals and fiber. In all samples with the addition of extrudates enriched with by-products, the content of hydroxymethylfurfural (HMF) increased with the increase of the amount of extrudates in cookies and with the increase of the amount of the by-product in the extrudate. All cookie samples had an HMF content less than 25 mg/kg. Samples with the addition of apple pomace received the best taste ratings, while the particle size of the extrudates had a significant effect on the colour and texture of cookies.
The addition of extrudates enriched with by-products did not affect the microbiological stability of the final product and all samples were safe for consumption.

Biljana Pajin* ; Faculty of Technology, University of Novi Sad, 21 000 Novi Sad, Serbia