The Detection And Control In Deep-fried Dough Sticks

Acrylamide has class2A carcinogen of medium toxicity, the exposure level ofacrylamide is particularly prominent in the group that regular intake of fried, baked food.Deep-fried dough sticks are very popular among Chinese people so detecting of acrylamidein food accurately, exploring the generating rule and controlling of the acrylamide contenteffectively is of great significance for the safety edibling of frying food.This thesis optimized the evaluation method of AA in the Asparagin/Glucose system inthe first place. By using the HPLC, it was found that the LOD level of model system was0.031μg/mL, and that of LOQ was0.095μg/mL. The standard deviation of intra day andinter day were2.4%and4.4%, respectively. The average recovery of standard addition was96.7%. After the optimization of pre-processing and instrument parameters, the LOD levelof this method was8.3μg/kg and LOQ was25.4μg/kg in food samples. By the use ofHPLC-MS/MS, the AA content in the fried dough sticks was determined. The pre-treatmentof fried dough sticks was optimized in the meantime. Furthermore, the samples wereextracted and purified with Agilent Chem Elut solid phase extraction column. It was foundthat the LOD value of own method was8.3μg/kg, LOQ was25.4μg/kg, the standarddeviation of intra day and inter day ranged from2.1%~4.4%and the average recovery ofstandard addition was from83.1%~96.8%.Effects of reaction time, temperature and molar concentration on the generationamount of acrylamide in the model system were investigated. The relationship between thecolor and those factors was studied in the meantime. It was found that with the increasing ofall the three factors, the content of acrylamide was increased first and then decreased, andthe color of the model system deepened with the increasing in AA content. However, it wasalso found that the color of the model system deepened continuously with the reaction time even at lower AA concent. The RSM analysis was carried based on single factor experiment.Results showed that the priority condition for AA generation of the system was reactiontime of75min a reaction temperature of200℃and a molar concentration of the substrateof1mmol/mL.The effect of additives to the AA formation was also inverstigated. Gly、Glu、Tau andVc were chosen as the additives. The additives were added at the priority condition. It wasfound that Gly has the highest inhibitory rate on the generation of AA (38.17%). The fourkinds of additives were mixed to get six groups of compound additives, which wereGly/Glu, Gly/Vc, Tau/Vc, Tau/Gly, Tau/Glu, Glu/Vc. Among the six groups, Gly/Glu,Gly/Vc, Tau/Vc have obvious inhibitory effect on AA of the model system, and the highestinhibition rate were67.29%,58.97%and51.74%, respectively, which were significantlybetter than those using a single additive at the same level. Thus, the three binary additiveswere chosen as the AA inhibiter in fried dough sticks.The relationship of frying condition and AA content was investigated as well. Resultsshowed that AA content was increased at longer frying time and at the same the frying time,AA content increased first with the increasing of frying temperature and then decreased.And at constant frying time and temperature, acrylamide contentfirst increased and thendecreased with the increasing of water content. By combining the sensory evaluation andacrylamide generation amount, it was found that the conditions for the production ofdeep-fried dough sticks were as follows: the ratio of the flour and water is1:0.6, the mixingand frying temperature was190℃and the time was140s; Under this circumstance, theacrylamide content in non-aluminum deep-fried dough sticks was significantly higher thanthat in alum ones. The best inhibition rates of Gly/Glu, Gly/Vc and Tau/Vc to alumdeep-fried dough sticks were89.9%,83.8%and95.6%, respectively (the amount of additivewas0.25%), and those for non aluminum deep-fried dough sticks were92.5%(the amountof additive was0.25%),86.5%(the amount of additive was0.05%) and81.6%(the amount of additive was s0.05%), respectively. By combing the inhibition condition of acrylamideand the quality of fried dough sticks, the optimal additive was determined to be Gly/Glu foralum deep-fried dough sticks (the inhibition rate of which was84.3%at an amount of0.15%), and that for non alum deep fried dough sticks was Gly/Vc (the inhibition rate ofwhich was86.5%at an amount of0.1%).