Application Of Hydroxymethyl Furfural In The Evaluation Of Dairy Thermal Damagey

Heat treatment will cause the loss of nutrients during processing of dairy, products, caused by the combination of lysine, arginine residues in the protein with the lactose and other carbohydrates, lead to the protein digestion and absorption difficulties. As one of the markers, Hydroxymethylfurfural was analyzed and summarized in the chemical reactions that occur in the dairy.Two ways that 5-hydroxymethylfurfural (HMF) from the heat treatment process of the foods were free type (F-HMF) and bound type (B-HMF). Hydrolyzed also form Amadori products and isomerizate of reducing sugar, it can be used as a valid marker of the degree of injury to assessing the quality of food proteins. The method of determination F-HMF: precipitate protein by 40% and 4% trichloroacetic acid, obtained the supernatant to determine, the results was:coefficient of variation of 12.70%, the recovery rate was 93.6%, B-HMF measuring method:precipitated protein by trichloroacetic acid method, Amadori product in precipitation be hydrolyze use of oxalic acid obtain the acid hydrolysis, the final determination was the content of hydroxymethylfurfural which occurs in the course of the Maillard reaction. The results show that:the optimal conditions for the hydrolysis of the Amadori product were:oxalic acid concentration of 1.07 mol/L,22.22mL oxalic/g protein, hydrolysis 240min. The detection limit of the method is 0.045μg/mL, the coefficient of variation of 7.9%, and the recovery rate was 92.2%.Heating experiment analysis of simple model of caseinate-lactose model and whey protein-lactose indicated that that in 105 min the F-HMF and heating time had a linear relationship between F-HMF and time:Model I:y=0.024x+0.040, R2=0.993, the Model Ⅱ:y=0.016x+0.627, R2=0.900, within in 180min relationship of B-HMF and time model Ⅰ y= 0.093x+7.45, R2=0.989, model Ⅱ, y=0.009x+7.796 R2=0.956.the content of HMF in Model with the heat treatment temperature was not a simple linear relationship, do polynomial relationship analysis found there having a good correlation, the relationship between content of free hydroxymethylfurfural and the heating temperature, model Ⅰ:y= 0.001x2-0.176x+5.843, R2=0.948, the model Ⅱ:y=0.001x2-0.167x+5.670, R2=0.868, the relationship of B-HMF and heating temperature, model Ⅰ y=0.026x2-3.782x+135.4, R2=0.890, y=0.016x2-2.434x+89.57, R2=0.88.Storage test about UHT milk, whole milk powder, skim milk powder and infant formula showed that the Pearson Correlation Coefficient of UHT milk, between packaging methods and the content of F-HMF is extremely significant, Pearson Correlation Coefficient between the content of B-HMF and storage temperature relationship is highly significant, and significant relationship with storage time, To solid milk, the F-HMF and B-HMF with storage time relations are very significant, but the relationship between the storage temperature of 4℃ and 37℃ only the content of Bound-hydroxymethylfurfural has a significantly relations.