The factors determining the generation of aroma in starch extrudates containing added ingredients with aroma precursors were elucidated. Analyses were performed using headspace analysis of raw materials and extrudates and subsequent analysis by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O. Study I described the volatile, amino acid and fatty acid profiles of Hydrolised vegetable protein (HVP)and Soy protein isolate (SPI). Studies II, III and IV descibed the volatiles developed from extrusion of different feedstocks under mild and extreme processing conditions. Wheat starch was chosen as the carrier.A comparison of the influence of the three different ingredients HVP, SPI and glucose, added to the starch feed, showed the formation of Strecker aldehydes and Maillard-type compounds were significantly affected by the addition of these ingredients. The work in this thesis demonstrated that the addition of ingredients such as HVP, SPI, glucose, cysteine, cysteine-HCI, modifies the aroma of wheat starch extrudates. Furthermore, it showed the changes in conditions of extrusion and pH will greatly influence the aroma profile of the products. / Doctor of Philosophy (PhD)