Study On Stability Of Vitamin C In Infant Formulas

Breast was the ideal source of nutrition for infants, whereas the proportion of beast-feeding was very low for infants in view of many reasons.Infant formula powders was the main source of Vitamin C for infants,who had scurvy for lack of Vitamin C.It was easily oxidized,whose stability was effected by many factors, so it’s of paramount importance to study the factors affecting the stability and degradation mechanism of Vitamin C for guaranteeing the quality of infant formula powders and the health of infants.Firstly,the effects of light,temperature,pH,oxidant,anti-oxidant,metal ions, saccharides on stability of ascorbic acid(AA) were studied. Results showed that it was more stable in the darkness and fluorescent with70%residual compared with in the sunlight with less40%residual after6h;high temperature led to86.5%loss after3h under60℃; AA yielded almost90%deterioration after30min in0.48%H2O2;more than40%loss of AA in neutral and alkaline conditions.AA could protect Vitamin E(VE) in the hydroalcoholic system.Cu2+and Fe3+could lead to large loss of AA. No influences were observed when glucose and sucrose existed.Secondly,the research was carried out to determine the effects of initial addition,VE, malysite,cupric salt,ascorbyl palmitate,choline,DHA on stability of VC during processing and storage.Results demonstrated that during the processing,Vitamin C was stable with only3%loss as other substances wasn’t existing;more initial addictive could lead more less;VE could cause less loss of VC;malysite could accelerate the loss rate of VC,cupric salt could lead large loss of VC with12.54%deterioration when adding0.45mg/100g;the mixture of the two metal salt could increase the loss of VC in terms of adding single metal salt;AP and DHA had sheltering effect on VC,which wasn’t affected by choline.During storage, more initial addition could lead more loss;the anti-oxidant mechanism between VE and VC was associated with relative dose ratio; the stability of VC was strengthened by Cu2+after processing;the mixture of the two metal salt could lead to loss of VC significantly with exception of comparing with adding single metal salt; AP could protect VC effectively,which was more stable in samples containing DHA; malysite and choline had no influence on VC.Furthermore,the content and stability of vitamin C in infant formula during process was assessed.The heat sterilization could affect the stability of VC significantly,while homogeneous and fluidization had no effects on VC.Finally, the thermal degradation kinetics of ascorbic acid(AA), dehydroascorbic acid(DHAA) and Vitamin C were determined in infant formula milk powder during preparing and storage.The results showed that the degradation of AA and VC during preparing followed a zero order kinetic model,and DHAA degradation fitted to a first order kinetic model.The activation energy were16.71kJ/mol、19.50kJ/mol、12.04kJ/mol respectively. Vitamin C lost37.7%-65.6%with temperature ranging from40℃to70℃after one hour. First order model could describe well the VC and DHAA degradation data during storage.It needed160d,78d,69d from the initial content(70mg/100g)to the minimum content (40mg/100g) according to the degradation rates under27℃,37℃,45℃.The stability of Vitamin C in infant formula powders was studied systematically,the prospect of research direction was discussed at last.