The Effect Of Damaged Starch In Flours On Acrylamide Formation And Starch Digestibility

The effects of damaged starch and yeast fermentation on the formation of acrylamide in wheat bread were studied,the reducing sugar and asparagine content in the dough also determined.The effect of asparagine and reducing sugar on the acrylamide formation in bread were analysed,we also determined the distribution of acrylamide in different parts of the bread,and also studied the starch digestibility of the bread.The results are as follows:(1)Four wheat cultivars were milled separately by three laboratory mills to obtain whole wheat flours with damaged starch content ranging from 1.66%to 6.56%,the damaged starch content of zhongmail75 through Junior mill was the lowest,however,the damaged starch content of 13CA64 through Bhuler mill was the highest.The reducing sugar content of the 12 kinds of flours were measured through Megazyme assay kit and the amount are ranging from 0.11 to 0.18%.(2)The acrylamide content in 12 kinds of fermented and unfermented bread were determined by high performance liquid chromatography.The acrylamide content in fermented bread were 0.12?1.09 ?g/g and the acrylamide content in unfermented bread were 0.30?2.23 ?g/g.More acrylamide was formed in the crust than in the crumb,the acrylamide content in unfermented bread crust and crumb were 0.72?2.23 ?g/g and 0.30?1.45 ?g/g,however the acrylamide content in fermented bread crust and crumb were 0.28?1.09 and 0.12?0.64 ?g/g.(3)Through mathematical analysis shows that a positive correlation was found between the damaged starch content of wheat flours and acrylamide content of bread.(4)Yeast fermentation decreased the content of asparagine by 40 to 60%in the dough,but increased the content of reducing sugar substantially.Dough fermentation decreased the content of acrylamide in bread by 50?60%compared with the unleavened bread.(5)By measuring different parts of starch digestion of bread,we found that starch digestibility in bread crust is lower than the starch digestibility in the bread crumb.Through the study of the structure of starch in bread,it occurs gelation entirely in the starch in bread crust and crumb,therefore,we speculated that more Maillard reaction products in the bread curst is a major factor which reduce the digestion of starch.Through this study,we have come to the following conclusions:damaged starch content of wheat flour and dough fermentation are major determinants of the formation of acrylamide in bread.The mitigation of acrylamide formation in bread can be achieved by choosing a flour with a low amount of damaged starch and by fermentation of the dough.