Study On Mitigation Of Monochloropropanediol Esters And Glycidyl Esters In Biscuits And Changes In Product Quality

Bakery products are widely consumed around the world due to their unique features,such as distinctive taste,delicious flavor,instant food,long shelf-life and so on.However,recent studies have shown that monochloropropanediol esters(MCPDEs)and glycidyl esters(GEs),commonly regarded as thermal process contaminants,are widely distributed in fat-rich bakery products.Meanwhile,toxicological studies have confirmed that MCPDEs and GEs can be hydrolyzed into free 3-monochloropropanediol(3-MCPD)and glycidol by lipase in vivo,respectively.The 3-MCPD and glycidol are consided as Group 2B and 2A carcinogens with potential renal toxicity and genotoxicity by the International Agency for Research on Cancer,respectively.Therefore,long-term consumption of fat-rich bakery products containing MCPDEs and GEs has a potential threat to consumer's health,which has aroused widespread concern.Currently,European Commission has set limits on MCPDEs and GEs contents in related foods.Therefore,in order to effectively control the formation of MCPDEs and GEs and ensure the nutrition and safety of fat-rich bakery products,firstly,in this study,a simultaneous determination method of MCPDEs and GEs was established and content levels of MCPDEs and GEs in traditional fat-rich bakery products were investigated.After that,biscuits were selected as the model of baking system for fat-rich bakery products,and the effects of baking conditions and oil types on the formation of MCPDEs and GEs as well as the sensory characteristics of biscuits were discussed.Finally,L-cysteine,commonly used as a nutritious supplementary in food,was selected as the inhibitor of MCPDEs and GEs in biscuits,and its possible inhibitory mechanism was also explored.The main research contents and results were as follows:(1)Establishment of simultaneous determination method and investigation of content levels of MCPDEs and GEs in fat-rich bakery productsA GC-MS method for simultaneous determination of 3-MCPDEs,2-MCPDEs and GEs in fat-rich bakery products was established.Methodological verification results were as follows: the limit of detection and limit of quantitation of 3-MCPDEs and 2-MCPDEs were0.0089 mg/kg and 0.0296 mg/kg,respectively.The limit of detection and limit of quantitation of GEs were 0.0159 mg/kg and 0.0528 mg/kg,respectively.The average recoveries were between 83.3% and 98.0%,and the relative standard deviations were between 2.94% and5.90%.The results demonstrated that the established method exhibited high sensitivity,accuracy and reproducibility,which could meet accurate quantitative requirements for simultaneous determination of 3-MCPDEs,2-MCPDEs and GEs in fat-rich bakery products.Furthermore,the content levels of MCPDEs and GEs in traditional fat-rich bakery products were investigated.The results showed that 3-MCPDEs,2-MCPDEs and GEs generally occurred in all samples with a content range of 0.03 to 0.94 mg/kg,0.01 to 0.43 mg/kg and 0to 0.47 mg/kg,respectively.Among the samples,the content levels of 3-MCPDEs,2-MCPDEs and GEs in biscuit products were higher.(2)Effects of baking conditions and oil types on the formation of MCPDEs and GEs as well as quality of biscuitsBiscuits were selected as the representative system of fat-rich bakery products,and the effects of baking conditions and oil types on the formation of MCPDEs and GEs in biscuits as well as product quality were explored.The results indicated that 3-MCPDEs,2-MCPDEs and GEs contents during baking exhibited a trend of increasing first and decreasing then,which indicated that the baking process promoted the formation of three harmful contaminants in biscuits.Moreover,the formation and degradation of three harmful contaminants occurred simultaneously during the baking process,and the equilibrium reaction was affected by both baking temperature and time.On the basis of optimum baking condition,the effect of oil types on the contents of 3-MCPDEs,2-MCPDEs and GEs in biscuits was further investigated.The results showed that oils and fats played an important role in 3-MCPDEs,2-MCPDEs and GEs contents in biscuits.Some of common oils and fats,namly,palm oil,butter,margarine and lard all led to the formation of three harmful contaminants during baking.However,red palm oil can significantly reduce the amount of three harmful contaminants in biscuits.Furthermore,red palm oil could not only satisfy the sensory quality requirements of biscuits,but also provide the products with better color and higher nutritional value due to its high contents of natural bioactive compounds(?-Carotene and VE).(3)Inhibitory effect of L-cysteine on MCPDEs and GEs in biscuits and its effect on product qualityBiscuits prepared with palm oil and rice bran oil were selected as food matrix to explore the inhibitory effect of L-cysteine on MCPDEs and GEs and its effect on product quality.The results demonstrated that the addition of L-cysteine could effectively reduce the contents of3-MCPDEs,2-MCPDEs and GEs in biscuits,and its inhibition rates enhanced with the increase of the amount of L-cysteine.When the addition amount of L-cysteine was 0.08%,its inhibition rates on 3-MCPDEs,2-MCPDEs and GEs in biscuits were 22.39% to 35.89%,16.08% to 33.97% and 28.70% to 30.98%,respectively,exhibiting higher inhibition rates than TBHQ antioxidant.The possible inhibitory mechanism of L-cysteine and TBHQ on MCPDEs and GEs in biscuits was further explored by electron spin resonance(ESR)and fourier transform infrared spectroscopy(FTIR).The results indicated that different from the free radical scavenging mechanism of TBHQ,L-cysteine could not inhibit the formation of MCPDEs and GEs by radical scavenging.It was speculated that the reduction of MCPDEs and GEs might be attributed to direct substitution reaction and ring-opening reaction.Moreover,the addition of L-cysteine could provide new flavor,brighter color and more crispy texture to biscuits.Therefore,L-cysteine,commonly used as a nutritious supplementary in food,not only improved the nutritional and sensory quality of biscuits,but also effectively reduced the contaminants contents,which provided a new idea for the production of biscuits with high quality and low contaminants.