The effects of microwave assisted baking on maillard reaction products in gluten free biscuits produced with different formulations

The aim of the thesis is to evaluate the effects of formulation and process conditions on the amounts of acrylamide, 5-hydroxymethylfurfural (HMF) and furan, which are considered as heat treatment contaminants in gluten-free biscuits, selected as model food, and to limit the formation of these contaminants to the maximum level. For this purpose, in the first stage, the effect of different leavening agents (sodium acid pyrophosphate and glucono delta lactone), different sweeteners (sorbitol, mannitol and isomalt) sweetener rates (30, 50 and 75%), and the effect of the addition of black tea extract was evaluated on the formation of acrylamide, HMF and furan in chestnut flour substituted gluten-free biscuits. Acrylamide and furan content of the samples were determined quantitatively by gas chromatography-mass spectrometry (GC-MS), while HMF content of biscuit samples was determined by high performance liquid chromatography (HPLC) after appropriate extraction conditions. As a result of the experiments, the lowest amount of acrylamide (160.21±12.52 µg/kg) was detected in samples containing 75% sorbitol. Additionally, by adding black tea extract to the formulation, the amount of acrylamide could be significantly reduced. Moreover, it was observed that the hardness values of the samples decreased with the use of sodium acid pyrophosphate for the samples containing 75% sorbitol. In the second stage of the study, the effects of the chestnut flour:rice flour ratio along with the temperature and time of the cooking process were determined using the D-Optimal combined design, and the most suitable chestnut flour:rice flour ratio in terms of acrylamide, HMF and furan formation was 44.171:55.829 while the optimum cooking temperature was 175.16°C and optimum cooking time was 6 minutes. It was observed that there was an increasing trend in the amounts of acrylamide, HMF and furan as the baking time of the biscuit samples increased. On the other hand, it was determined that as the amount of chestnut flour increased in the formulation, the amount of Maillard reaction (MR) products also increased. The increase in temperature similarly caused an increase in the amounts of acrylamide, HMF and furan. In the third stage of the study, the samples baked at 175.16°C for 6 minutes with a chestnut flour:rice flour ratio of 44.171:55.829, were packaged with aluminum polyethylene (ALPE) packaging material and stored in a refrigerated incubator at 25°C at 46.67% RH for 90 days. It was observed that as the storage time increased, the moisture content and water activity of the samples increased, while the total phenolic content and antioxidant activity values decreased. However, as the storage time increased, the acrylamide and HMF amounts of the samples decreased. The content of furan also decreased, however this decrease was not found to be statistically significant. The lowest amount of acrylamide (124.21±4.46 µg/kg) was detected in biscuits containing only rice flour and stored for 90 days, while the lowest amount of furan (81.51±2.10 ng/g) was detected for the samples containing both chestnut and rice flours and baked using microwave-assisted convection method. On the other hand, HMF was not detected in any of the samples as of the 7th day of storage. As storage period progressed, a decrease in the crispiness value, which is among the sensory properties of the samples, was observed. It was determined that there was an increase in the hardness values of the samples. As a result, it was observed that both the formulation and baking conditions significantly affected the amounts of acrylamide, HMF and furan, and it was determined that increasing the process temperature could increase the amounts of acrylamide, HMF and furan in the samples to a statistically significant degree. It is thought that the amounts of these components can be limited by using appropriate baking conditions along with the addition of black tea extract to the samples. Keywords: Acrylamide, Furan, Gluten-free biscuit, HMF, Maillard reaction.