Analysis And Cytotoxicity Evaluation Of Polar Components In Frying Oil

Several chemical changes undergo during frying oil heated or fried food, includingoxidation, hydrolysis, polymerization, which produced a variety of polar components in thesereactions, such as oxidized triglycerides oligo (TGO), oxidized triglycerides dimer (TGD),oxidize triglycerides (ox-TG), free fatty acids (FFA) and so on. These polar componentsenriched in food by frying oil would affect human health. The experiment researched therelationship between peroxide value, carbonyl value, acid value, anisidine value and thecontent of polar components in frying oil respectively,rapid detection for the content of polarcomponents in frying oil, the polar components analyzed by HPLC and evaluating thecytotoxicity of polar components.Firstly, this work analysised the peroxide value, carbonyl value, acid value, anisidinevalue and the content of polar components in the process of heating frying oil, compared therelationship between peroxide value, carbonyl value, acid value, anisidine value and thecontent of polar components in frying oil respectively and investigated the correlationbetween the four physical and chemical indicators and the content of polar components infrying oil. The correlation coefficient that the peroxide value, carbonyl value, acid value,anisidine value and the content of polar components was0.6563,0.9161,0.9202,0.8395byanalysising. The results showed that the correlation coefficient between the physicochemicalof frying oil and polar components content was beyond the scope of effective regulations.And, the content of polar components in frying oil were detected by low field nuclearmagnetic resonance (NMR) and conductivity method, compared the effectiveness of the twomethods, and verified conductivity method through the accuracy, repeatability test. In theexperiment, NMR couldn’t accurately detect the content of polar compounds, only from thelength of molecular chain to explain changes in relaxation time; but the correlation coefficientbetween electric conductivity and the polar compounds of heating frying oil, frying oil afterfried chips and tofo skin were0.9228,0.9716,0.9358. The results showed that both heatingfrying oil and fried food, polar components content of frying oil had a good correlation withelectric conductivity. Then, by determining repeatability and verifying the accuracy of thismethod, the relative standard deviations of repeatability was between1.08%-2.07%and thecorrelation coefficient of accuracy was0.9663, it was concluded that the conductivitymeethod is a rapid, efficient and convenient method to detect the content of polar componentsin frying oil.Then, in the experiment the polar components were isolated by HPLC, and this methodwas applied to the preparation. The polar components are confirmed by high-performancesize-exclusion Chrom-atography (HPSEC) and were divided into four parts, oxidizedtriglycerides oligomer (TGO), oxidized triglycerides dimer (TGD), oxidized triglycerides (ox-TG), and free fatty acids (FFA).At last, the polar components of frying oil through the oil into the frying food had acertain influence to human health. In the experiment, the toxicity of total polarcomponents(TPM) isolated by adsorption chromatography using silica columns, TGD andox-TG prepared by HPLC were detected by cytotoxicity experiment. After evaluating cellproliferation by MTT, observing cell morphology by LSCM, determining cell apoptosis andcell cycle by flow cytometry, the results showed that: the cell growth inhibition incresed withthe polar components concentration increased from0.05mg/mL to2.00mg/mL; the cellmorphology changed by LSCM, the size of apoptotic cells were heterogeneity, the nuclei wascondensation and the color were white; cell cycle experiments showed that all three types ofpolar substances can inhibit the cells in S phase.The results of apoptosis showed that cellapoptosis rate increase with the increase of concentration and action time of three polarcomponents,respsctively.From the above results,we got that the most toxic to HepG2cellsfollowed ox-TG,TGD,TPM.