Detection Of Carminic Acid And Shikonin In Baked Food

As natural food additives,the cochineal red whose main effect ingredient is carminic acid and comfrey whose main effect ingredient is shikonin are widely used in food processing.In recent years,the problems of over-range and over-dose use of food additives in baked goods have become increasingly prominent,which caused much difficulties in food safety supervision.The standard dose of cochineal red and comfrey red in the baked foods has been clearly specified according to existing national food safety standards on the use of food additives,but there are no standards for detection methods.In this paper,a variety of common baked foods such as moon cakes are taken as the research objects.After optimization of samples pretreatment,chromatographic conditions and mass spectrometry conditions,two detection methods were established for the residual amount of carminic acid and shikonin in baked foods,including high performance liquid chromatography(HPLC)and Liquid chromatography-mass spectrometry(LC-MS/MS)methods.The main research contents and results of this paper are as follows:1.Establishment of high performance liquid chromatography(HPLC)method for content of carminic acid and shikonin in baked food.The sample was extracted with2%formic acid-methanol solution,purified by C₁₈ solid phase extraction column,separated by Agilent ZORBAX Eclipse XDB-C₁₈ column,and last determined by high performance liquid chromatography-diode array detector(HPLC-DAD).Methanol-0.02 mol/L ammonium dihydrogen phosphate solution is eluted as mobile phase.Carminic acid and shikonin were finally quantified with an external standard method.As the results show,when carminic acid in the range of 0.5?g/m L?100?g/m L and shikonin in the range of 1.0?g/m L?200?g/m L,the linear relationship is good with the correlation coefficients(R²)0.9997,0.9999,respectively.The detection limit and quantitation limit of carminic acid are 0.6 mg/kg and 2.0 mg/kg respectively;and those of shikonin are 1.2 mg/kg and 4.0 mg/kg.The standard recovery rate of carminic acid is 76.5%?97.6%with the relative standard deviation(RSD)of 2.2%?9.6%in testing 7 kinds of baked foods;and that of shikonin was75.8%?98.8%with the relative standard deviation(RSD)of 2.0%?8.9%.Based on its strong anti-interference,simple pre-treatment,high recovery rate and good precision,this method is suitable for the determination of carminic acid and shikonin in baked food.2.Establishment of liquid chromatography-tandem mass spectrometry(LC-MS/MS)method for content of carminic acid and shikonin in baked food.The target substance was extracted with 2%formic acid-methanol solution and purified by PRi ME column.Multiple reaction monitoring(MRM)mode was adopted to detect ionization by electrospray anion.The mobile phase was methanol-0.1%formic acid aqueous solution with using Agilent ZORBAX Plus C₁₈ as the chromatographic column.The content of carminic acid and shikonin were quantified by matrix matching standard curve external standard method.The results show that carminic acid had a good linear relationship in the range of 4.0 ng/m L?400 ng/m L,and shikonin had a good linear relationship in the range of 2.0 ng/m L?200 ng/m L.The correlation coefficient(R²)of them was between 0.9962?0.9991.The limits of detection for carminic acid and shikonin respectively were 0.03 mg/kg and 0.015mg/kg,and the limits of quantification for them were 0.10 mg/kg and 0.05 mg/kg.Among the five kinds of baked foods tested,the recovery rate of carminic acid spiked was 81.7%?97.8%and the relative standard deviation(RSD)was 4.2%?10.9%.The recovery rate of shikonin spiked was 82.6%?105.2%,and the relative standard deviation(RSD)was 2.8%?9.3%.This method is suitable for trace analysis of carminic acid and shikonin in baked food and confirming the target due to its simple treatment process and high recovery rate.