Effects Of Polar Components In Cream On The Odorants Of Heated Cream

Cream contributes a pleasant aroma to the baked foods.In this paper,the components and volatile compounds of cream were identified and analyzed,with emphasis on the polar components contributing to the flavor of cream,and the effects of different carbohydrates on the key odorants of heated cream were compared.Firstly,NMR and GC-MS techniques were used to identify the components and volatile compounds in the cream before and after heating.The changes between the two samples were combined to find the substances that had important effects on the key aroma compounds in the heated cream.Then,NMR technology was used to analyze the composition of polar components extracted by ethanol,and it was added to the ethanol-treated cream.The volatile compounds of all samples were compared by GC-MS,and sensory evaluation was assisted to determine the influence of polar components on flavor of heating cream.Finally,different carbohydrates were added to cream to study their effects on the key odorants.The specific research results are as follows:The polar and apolar components in cream were identified by NMR technique.The polar components mainly included lactose,free amino acids,free fatty acids and organic acids,and the non-polar components were mainly triglycerides and a few diglycerides and monoglycerides.After heating,the polar components in the cream were greatly reduced,of which lactose was reduced by 74%,aspartic acid and methionine by 83%and 82%,respectively,leucine,isoleucine and valine were all reduced by80%,and tyrosine,alanine,arginine and lysine were reduced by 78%,70%,33%and 18%,respectively.In the non-polar components,unsaturated fatty acids and saturated fatty acids were reduced 23%and18%,respectively,diglycerides by 17%,and 1-and 2-monoglycerides by14%and 60%,respectively.HS-SPME-GC-MS was also used to identify the key volatile compounds in the cream before and after heating,including lipid-derived compounds and Maillard reaction products.With thermal treatment,the growths of short-chain fatty acids and aldehydes were relatively small,but the increases in methyl ketones,lactones and Maillard reaction products were very significant,especially 2-heptanone,?-dodecalactone and furfural,which increased by 209,95 and 180 times,respectively,while methional,maltol and furaneol were only detected in the heated cream.Combining the changes of components and volatile compounds in the cream before and after heating,the results showed that the formation of the Maillard reaction products in the heated cream was the reason for the large reduction of polar components in cream,and the growth of aroma compounds derived from lipid causing the reduction of fatty acids in the cream.Moreover,the higher the contents of the components as flavor precursors in the cream,the more significant the growths of the volatile compounds in the heated cream formed from these substances.The polar components extracted by ethanol contained lactose(60%),free butanoic acid(0.01%),free amino acids(1.5%),organic acids(0.1%),?-aminobutyric acid(0.1%),phosphatidylethanolamine(7.7%),spphingolipids(4.9%)and phosphatidylcholine(9.16%).After instrumental detection,the content of butanoic acid was increased 2.6times in the cream with the addition of polar components,but the content of 2-heptanone was the highest in ethanol-treated cream.Compared with ethanol-treated cream,?-decalactone and?-dodecalactone were increased by 2 and 1.5 times in the cream with the addition of polar components,hexanal,(E,E)-2,4-decadienal and(E)-2-nonenal were increased by 1.75,2.8 and 2.2 times,respectively.Maillard reaction and caramelization products were significantly increased with the addition of polar components.Compared with ethanol-treated cream,after adding polar components,3-methylbutanal and methional were increased by 7.4 and 2times,respectively,methylpyrazine was increased by 1.8 times,furfural,furanone and maltol were increased 17.6,5 and 5.7 times,respectively,and 2-methylbutanal,ethylpyrazine,2,3-dimethylpyrazine were only detected in the cream samples with the addition of polar components.And after sensory smell,the cream added polar components scored high in all sensory attributes,especially the"caramel"and"roasted"properties,and the‘sweet',‘buttery'and‘milk'attributes were close to those of cream with no significant differences.The ethanol-treated cream had the lowest scores in all attributes,with significant differences in the‘sweet',‘buttery',‘caramel'and‘roasted'attributes compared to the cream with the addition of polar components.Compared the effects of lactose and sucrose on the key odorants of heated cream,there were no significant differences in lipid-derived products between the cream samples supplemented with lactose and sucrose separately,and for Maillard reaction products,there were significant differences in 3-methylbutanal,methional,furfural,5-methyl-2-furancarboxaldehyde,2-furanmethanol,maltol,furaneol,and5-hydroxymethylfurfural.Compared the effects of glucose and galactose on the key odorants of heated cream,there were no significant differences between the samples,but the contents of the key odorants of heated cream with the addition of glucose were higher.After cluster analysis of the five samples separately,the cream with the addition of sucrose had the greatest difference from the other four samples,the cream with the addition of glucose was similar to the cream with the addition of galactose,the cream with the addition of lactose was similar to the heated cream,and the contents of short-chain fatty acids and aldehydes were increased in the cream with the addition of lactose.The main components in the cream before and after heating and the cream with the addition of lactose were analyzed by ~1H NMR.The results indicated that there were no significant differences in the contents of polar components and saturated fatty acids between the heated cream and the heated cream with the addition of lactose,while the contents of unsaturated fatty acids were decreased more after the addition of lactose.