Chemical changes occurring in nuts and oilseed varieties during roasting

Nuts and seeds, considered part of a healthy diet, can be consumed raw or roasted. Roasting provides desirable aroma, color, and also texture, thereby improving overall acceptability. Apart from the physical changes, chemical reactions such as the Maillard reaction, sugar degradation, lipid oxidation, protein denaturation, and vitamin degradation also take place during roasting and are affected by the temperature and time of the roasting process. The thermal process can also cause potentially adverse health effects by promoting the formation of potentially toxic or carcinogenic components and causing a loss of nutritional value. The route of these chemical reactions is extremely dependent on the reactants as much as reaction conditions such as pH, temperature, and moisture content. Within the scope of this thesis, in order to better understand the complex reaction systems that occur during the roasting of low-moisture, lipid-rich and sugar-limited foods containing the available amount of amino acids and sucrose, the changes in the concentrations of the reactants and the products formed were kinetically monitored. Accordingly, the lowest 5-hydroxymethylfurfural concentration was observed in pumpkin seeds due to low sucrose content, while the highest formation was found in sunflower seeds. Among the samples, the highest amount of furosine was found in pumpkin seeds. The most predominant α-dicarbonyl compounds were determined as 3-deoxyglucosone and methylglyoxal. The highest acrylamide concentration was found in almonds due to the higher content of free asparagine compared to other samples. The highest N-ε-carboxymethyllysine content was measured in sunflower seeds, whereas the highest N-ε-carboxyethyllysine was in pumpkin seeds. In addition, a kinetic model was proposed for Maillard reaction-caramelization and also for acrylamide formation during roasting of nuts and seeds as low moisture food systems by using a multiresponse kinetic modeling approach.