Degradation of Ascorbic Acid during Baking

Abstract Ascorbic acid is added during production of the bread as an industrial oxidizing agent in order to maintain rheological property of bread during baking. In order to determine the effect of temperature on the ascorbic acid content in  the dough during fermentation at 25 ºC, 35 ºC and 38ºC and baking temperature in which dough was prepared with mixture of 50 ppm ascorbic acid and 3 kg flour. Degradation of ascorbic acid for each stage was determined by using High Performance Liquid Chromatography (HPLC). k values were determined as 0.052, 0.0445 and 0.002  min^-1 at 25 ºC, 35 ºC and 38 ºC respectively.  When temperature of baking was increased to 200 ºC, 230 ºC and 210 ºC, the amount of ascorbic acid in the bread were decomposed by 76.8%, 77% and 77.8% respectively. Ascorbic acid is decomposed above 192ºC. Although the highest temperature in bread making reached 230ºC, ascorbic acid was not found to be 100% degraded. It was determined that the ascorbic acid did not completely degrade when the bread temperature was not above 100ºC. According to that kinetic calculations were estimated from the degradation of ascorbic acid which was followed a zero-order kinetic model.  Activation energies during fermentation and baking stages were calculated as 47.7kJ/mol and 27.69 kJ/mol respectively.

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