Study On The Quantities Change Of The5-Hydroxymethylfurfural In Milk Under The Different Heat Treatment And Shelf Life

In all kinds of liquid dairy products processing, raw milk are need to pass proper heattreatment to kill microorganisms, ensure the quality and safety of dairy products, and extend theshelf life of products. But milk is the thermal sensitive material; heat treatment processparameters can make big effect on the milk nutrients. Excessive heating can lead to part or allmilk nutrients lost, the stability of the emulsion system decreased, but insufficient heat treatmentcan't kill the pathogenic microorganisms in the milk. So scientific choosing different heattreatment process is particularly important, which can ensure the kill the harmful organisms, andcan try to reduce the heat loss of nutrients. This study aims to discuss the5-HMF as the milkheat degree validation of target sensitivity and direct the scientific of determine the different heattreatment processes.A High performance liquid chromatographic (HPLC) method was developedfor the quantities change of5-Hydroxymethylfurfural (5-HMF)in milk under the differentheating temperature and time, reveals its regularity changes. The main results are as follows：(1)Optimize the inspection method of5-HMFand feasibility evaluation.With the efficientfast and accurate detection of the5-HMF milk and improve the accuracy of the experiment forthe purpose, optimization the test of high performance liquid chromatography. The final of thebest conditions for the chromatography: Use pH3.8sodium acetate buffer: methanol=92:10asmobile phase, Ultraviolet wavelength detection284nm, Column temperature of35℃,Velocityis0.8mL/min, sample size is20μL. The average recovery of this method is93.81%, and therepeatability of relative standard deviation (RSD) is0.18%.The result show that this method canrapid determine the rule in quantities of5-HMF and exists a well linear relationship betweenpeak area and content, the determination results has high accuracy and reproducibility.(2)The quantities change of the5-Hydroxymethylfurfural in pasteurizing milk under thedifferent heat treatment. The results show that in the heating temperature for85℃conditions,with the extension of time(15s,30s,45s,60s,75s,90s),the quantities of5-HMF showeda rising trend, First shot up, slow rise and shooting up; In the heating time for15s and30sconditions, with the rise of temperature, the quantities of5-HMF showed a rising trend, thehigher the temperature, the more quantities of5-HMF, and heating time in30s were greater than15s. Under the pasteurizing process condition, the temperature has the greater influence thantime.Based on this, establishment of the liquid milk for thermal process parameters is: thepasteurization dairy temperature should be controlled at85±2℃, the time for15s, thisparameter is more scientific.(3)The quantities change of the5-Hydroxymethylfurfural in UHT milk under the sameheat time and different temperature. The results show that in the heating time for4s conditions, with the rise of temperature(133℃,135℃,137℃,139℃,141℃,143℃),the quantities of5-HMF showed a rising trend, the higher the temperature, the more quantities of5-HMF, And inmore than140℃temperature,5-HMF content increased rapidly. based on this, the UHT dairytemperature should be controlled at (137±2)℃, the time for4s, this parameter is morescientific..(4)The quantities change of the5-Hydroxymethylfurfural in UHT milk under the wholeshelf life. The results show that in the shelf pre-life (60d before), the quantities of5-HMFshowed a rising trend,but change is not obvious;in the day of61d-180d,with the extension oftime and he quantities of5-HMF heighten. Total trend is：Changes of the quantities of5-HMF isslow, as the storage time increased the more dramatic changes. So suggest that consumers would beas early as possible to drinking the milk products in the shelves are preferred.