Effect of flour type on Maillard reaction and acrylamide formation during toasting of bread crisp model systems and mitigation strategies

Maillard reaction along with caramelisation are the main chemical reactions occurring in bakery products. They are referred to as non enzymatic browning. In this work, the effect of flour type (wheat, rye and whole-wheat flours) and process conditions were investigated by using a bread crisp model system made up of flour, water and yeast. The bread was toasted at different temperature for different times. In a second set of experiments several additives (glycine, 0.1% on flour; asparaginase, 2000 U kg^-1 of flour and an antioxidant extract from green tea) were added to the basic formulations in order to test their ability in reducing the formation of potentially harmful Maillard reaction compounds such as HMF and acrylamide. Browning development and water content along with antioxidant activity were also monitored. Rye model systems produced more HMF and acrylamide at all temperature tested, while wholewheat systems produced less HMF, but more acrylamide than wheat one. The addition of glycine was effective in reducing acrylamide formation, and it increased browning development, antioxidant activity and HMF formation. Asparaginase reduced acrylamide formation up to 88% and had no effect on browning development and antioxidant activity. The addition of exogenous antioxidant compounds from green tea did not produce clear effect on acrylamide formation, thus it was not useful as mitigation strategy in bakery products, likely because of the low fat content.