Flavor And Taste Characteristics Of Partially Hydrogenated Oil And Preparation Of Its Alternative Fats

Partially hydrogenated oil（PHO）,characterized as with rich creamy flavor,full-bodied taste and excellent processing properties,was used to be an important part of specialty fats.But it has been resisted because of the safety risks associated with trans fatty acid.The existing"zero-trans"alternative fats have made progress in modelling the texture of PHO,but they still lack the characteristic creamy flavor and full-bodied taste.For this reason,the flavor,taste and their characteristic substances of PHO were systematically studied,the main missing flavor was obtained by enzymatic digestion of butter,a taste evaluation model and method was developed through the"composition-physical-taste"relationship,and a"zero-trans"alternative fat with a highly similar flavor and taste as PHO was prepared by multivariate blending.The main contents are as follows:Firstly,the representative PHO was selected by preference analysis,and their key flavor substances were identified by molecular sensory science techniques.Aroma recombination was carried out and then the main missing flavors were obtained by enzymatic hydrolysis of butter.The results showed that PHO possessed a strong flavor combined of green,creamy,greasy and beeswax aromas,which were synergistically presented by 14 flavor substances（relative odor activity value≥0.1）,including 6 aldehydes,4 ketones,2 lactones,1 ester and 1 acid;9 of them were key flavor substances（relative odor activity value≥1）,mainly octanal,（E）-2-decenal,nonanal,2,5-octanedione,（E）-2-undecenal,heptanal,2-nonanone,methyl decanoate,and hexanal;while the remaining five substances,2-octanone,2-hexanone,octanoic acid,γ-nonolactone and butyl decalactone,played a modifying role.Reorganisation of the above substances revealed ideal green and beeswax aromas,but weak creaminess.Enzymatic hydrolysis was further developed to obtain milk flavor enhancers,which was characterized by ketones,lactones and short chain acids.Secondly,the taste of PHO was evaluated according to the oral physiological mechanism of fat perception,and its physical properties were comprehensively analyzed.The results showed that the taste of PHO was characterized by strong greasiness,creaminess,aftertaste and weak coolness.Solid fat content（SFC）curve of PHO was flat,decreasing uniformly from 72%at 0℃to 4.2%at 35℃.Both melting and crystallization curves showed broad and flat small peaks,lower melting enthalpy（25.19 J/g）and crystallization enthalpy（52.92 J/g）,and formed a dense network of fine spherical crystals withβ’crystal in refrigerated and room temperature.In addition,the PHO had a significantly higher viscosity than other typical specialty fats,e.g.,fully hydrogenated palm kernel oil and stearin,coconut oil,palm liquid oil,etc.Thirdly,the mathematical correlation between"composition-physical properties-taste"was investigated by Pearson correlation and multiple linear regression analysis,and a taste evaluation model based on fatty acid composition and physical properties was established.The results showed that the fitting degree between taste and physical properties was satisfactory,reaching R²>0.88.Among them:Coolness=4.333+ΔH_{melting enthalpy}×0.050+C10:0×0.364–SFC（30°C）×0.035+C14:0×0.288（R²=0.887）;Greasiness=6.265+LCFA×0.110+SFC（25°C）×0.125-Crystal nucleation index n value（4°C）×0.632+T_{crystallization end temperature}×0.040（R²=0.901）;Creaminess=18.177+SFC（30°C）×0.235-SFC（10°C）×0.121+T_{melting end temperature}×0.190–ΔH_{crystallization enthalpy}×0.081（R²=0.916）;Aftertaste=5.769+T_{melting end temperature}×0.161+β’crystal×0.011+SFC（35°C）×0.347–MCFA×0.061（R²=0.922）.The fit coefficients of this evaluation model were all high and there were no co-linearity problems.Finally,long and medium chain fats were screened for binary and ternary blending based on the key fatty acids and physical property indexs in the evaluation model（6 groups in total）.The taste was predicted by the evaluation model to determine the optimal blending ratio.The results showed that soybean oil-fully hydrogenated palm kernel oil-fully hydrogenated soybean oil=45/45/10 exhibited the same SFC curve,melting-crystallization behavior（melting enthalpy 13.15 J/g,and crystallization enthalpy 50.56 J/g）,and crystal nucleation and growth methods as PHO.The predicted taste of the six blends was similar to actual taste scores（R²>0.91）,which verified the accuracy of the taste evaluation model.Furthermore,the flavor and taste of the prepared blend was not significantly different from PHO when the milk aroma enhancer was added to the sample,which resulted in a"zero-trans"alternative fat with desirable flavor and taste features.In conclusion,the flavor and taste characteristics of PHO and its characteristic substances were figured out,followed by breaking through enzymatic generation the key flavor technology and establishing a method to predict the taste based on the composition and physical properties of fats.The ideal flavor and taste of"zero trans"alternative fat was prepared,which solved the problems of insufficient flavor and single taste of the existing alternative fats,and provided a new way to manufacture"zero trans"food specialty fats using non-PHO as raw material.