Study On The Thermodynamic Parameters Of Sugar-acid Solution And The Binary Taste Evaluation

Sweet-sour taste is a favorite taste.Studying the thermodynamics of sugar-acid solutions is of great significance for understanding the physicochemical mechanism of taste interactions.In this study,two natural sugars,fructose and sucrose,were selected,and pectin was selected as the viscous medium.The thermodynamic properties of sugar acids in the polysaccharide medium were studied based on volume characteristics and viscosity characteristics.The linear scale method was used to evaluate the sensory characteristics of the sugar-acid solution,and the correlation between the thermodynamic properties and the sensory characteristics of the sugar-acid solution was studied in order to understand the physical-chemical mechanism of the sweet-acid interaction.?1?Thermodynamic properties of sugar acid solutionDensity method and viscosity method were used to study the density and viscosity changes of sugar-acid solution in dilute solution and polysaccharide medium.The apparent molar volume,transferred molar volume and viscosity of sweet substances in sugar-acid solution were calculated.Coefficients the thermodynamic properties of the mixed system of sweet and sour substances in the sugar-acid system are obtained.We found that the density of sugar-acid solutions increases with increasing sugar or citric acid or pectin concentration,the apparent molar volume of sucrose in aqueous citric acid solutions decreases with increasing sucrose concentration,and with citric acid as the concentration increases,it decreases.When the polysaccharide medium pectin was added,the apparent molar volume of sucrose decreased slightly compared with that in the dilute solution,and it decreased with the increase of pectin concentration.The sucrose-citric acid system and fructose citric acid both showed negative?_tV₂⁰ values,indicating that the hydrophilic-hydrophobic and hydrophobic-hydrophobic effects in the sugar-acid solution were stronger than the hydrophilic-hydrophilic effects.?2?Evaluation of sensory characteristics such as sweetness intensity and acidity intensity of sugar-acid solutionSensory evaluation of sugar acid solutions was performed using a linear scale method.It can be seen that in the sucrose citric acid dilute solution,in the low-concentration sucrose solution,the sweetness intensity of the solution after adding pectin is greater than the sweetness intensity of the dilute solution;but after adding pectin,the same proportion of sugar acid solution the intensity of sweetness decreases.In the fructose-citric acid solution,when the fructose concentration is low,the sweetness intensity of the sugar-acid solution is increased after adding 0.3 wt%pectin,and at the same fructose concentration,the lemon when the acid concentration is higher,the sweetness intensity is lower than that in the dilute solution;when the fructose concentration is 0.2 mol Kg^-1 or more,the sweetness intensity decreases as the pectin concentration increases.The acidity intensity of the sugar-acid mixed solution decreased with the increase of pectin concentration.In addition,the change of sweetness intensity with the concentration of pectin in the system is consistent with the change of the molar molar volume of sugar in citric acid solution.?3?Correlation between sensory characteristics and physicochemical parameters of sugar-acid solutionThe correlation between physicochemical parameters and sensory characteristics of sugar-acid solution was studied by statistical analysis.In the PLS model of the sweetness intensity of the sucrose-citric acid system,sucrose concentration,citric acid concentration,refractive index and density were positively correlated with the sweetness intensity among the 10 variables,and the rest were negatively correlated.In the acidity intensity model of sucrose-citric acid system,it was found that citric acid concentration,refractive index and density have important effects on acidity intensity.In the PLS model of the sweetness intensity of fructose,the fructose concentration,refractive index and density are positively correlated with the sweetness intensity.In the PLS model of the fructose-citric acid acidity intensity PLS model,the citric acid concentration,refractive index and density have an effect on the acidity intensity.Have a significant impact.According to the principal component analysis method,the contribution rate of each principal component was analyzed,and it was found that the major effects on the sensory characteristics of the sugar acid solution were sugar concentration,citric acid concentration,pectin concentration,density,refractive index,and electrical conductivity.Applying the method of least squares with sweetness and acidity as indicators to analyze the main variables affecting the sugar-acid solution,the conclusion obtained confirms that sugar concentration,citric acid concentration,pectin concentration,density,refractive index and electrical conductivity etc.The influence of sensory characteristics is the main variable.