Study Of Sweetness Recognition With Fullerenols As Artificial Chemoreceptor Model: Fluorescence Spectrum And DSC Study

By way of the additive used in daily life frequently,sweeteners occupy important status in food science field.However,because of the restriction of experiment condition and particularity of sweet taste,people can't understand the sweetness mechanism of the sweetness molecules up to the present.In this paper,we used fullerenols as artificial sweet taste chemoreceptor,via determined fluorescence kinetics and thermodynamic parameters of the interaction between fullerenols and typical sweeteners, correlated these parameters with the sweeteners' sensory sweetness,and established an artificial sweet taste chemoreceptor model which is feasible to have a research.The main research work is as follows:(1) Synthesization of Multi-hydroxylized fullerenols.The artificial sweet taste chemoceptor was catalysed by tetrabutylammonium hydroxide (TBAH),the spectrum properties of fullerenols were characterized by FT-IR,NMR and Fluorescence.The phenomenon of self-aggregation of fullerenols appeared in water solution during the experiment,the mechanism of self-aggregation was expatiated by TEM,Zeta Potential/Size and fluorescence.This conclusion settled the methodological basic for it used as an artificial sweet taste chemoreceptor in the latter sweet recognition study.(2) A Study on sweet recognition of artificial sweet taste chemoreceptor by Fluorescence Titration Method.Based on the fluorescence titration experiment,the concentration of fullerenols to be ascertained was 1×10^-5 mol/L firstly,then we got the fluorescence specific-increase curves of different sweet compounds.The binding proportion was 1:1 during initial stages of titration,the binding constants at 25℃and 50℃were achieved, it could obtained thermodynamic parameters by classical thermodynamic formulas,then had fitting it with the logarithm value of sensory sweetness intensity,polynomials are as follows:LgS=0.031265A₁-16742.4t₁-0.02632A₂-14100.1t₂+1.84666;LgS=352.17+1.28×l0⁵k₁+7.91xl0⁵k₂+1.74xl0⁴ln(k₂/k₁)-0.55â–³H +0.012â–³G₁;The corresponding correlation coefficients were 0.9943 and 0.9998,it meaned that could recognize sensory sweetness by the method of fluorescence kinetics and thermodynamics perfectly.(3) A study on the sweet recognition of artificial sweet taste chemoreceptor by Differential Scanning Calorimetry(DSC).Based the DSC calorimetry curves of fullerenols-sweeteners supramolecular compounds,gained the transition temperature(T_m) and other thermodynamic parameters by NONLINEAR LEAST SQUARE METHOD.We used these parameters fitting for the sensory sweetness, received the correlate equation:Lg S=-0.9931T_m+0.015123â–³H+0.000243â–³H_v-2.40197n+0.1803T_1/2 -4.70375â–³S+0.012â–³G₁;the correlation coefficient R=0.9956,it tells us that DSC thermodynamic parameters also can used in recognize sensory sweetness. Started from the chemical essence of receptor-ligand,taken fullerenols as artificial sweet taste chemoreceptor,used fluorescence spectrum and DSC as experiment technique means,based on classical thermodynamic theory at the same time,obtained the correlation fitting equation between parameters and sensory sweetness,the feasibility of taken fullerenols as artificial sweet taste chemoreceptor was verified, established the correspond experiment model,and settled the foundation for the further systematically study.