| In this study,fresh hawthorn was selected as the raw material,and the extraction process of pectin was optimized by hot water extraction,ultrasonic assisted hot water extraction and enzyme-assisted hot water extraction respectively,and the optimized pectin product was tested for its yield,total sugar content,total phenol content,galacturonic acid content,esterification degree,and viscosity;Finally,pectinase was used to induce the synthesis of pectin oligosaccharides,and then it was separated and purified by ion exchange column chromatography to obtain a series of pectic oligosaccharides,its anti-glycation in infant formula milk powder was preliminary investigated.The result is as follows:1.Optimization of extracting process of hawthorn pectin:1)The optimal technological conditions for ultrasound-assisted hot water extraction of pectin:solid-liquid ratio 1:20(g/mL),ultrasonic temperature 70?,extraction time 10 min,ultrasonic power 500 W(100%).2)The optimum technological conditions for enzymatically assisted hot water extraction of pectin:the best conditions for the addition of xylanase 70 U/g,the enzymolysis temperature 50.5?,the enzymolysis time 3.0 h,and the solvent pH 7.0.3)Comparing the yields of three pectin extraction methods,the yield of pectin by enzyme-assisted hot water extraction was the highest,which was 16.8%,then the yield of hot water extracted pectin was 10.1%,and the ultrasonic assisted method was the lowest,only 6.4%.2.The results of physicochemical properties analysis of pectin polysaccharides show that the total sugar,total phenol and galacturonic acid content of pectin obtained by ultrasonic-assisted hot water extraction method is the highest,and the esterification degree and viscosity of pectin obtained by enzyme-assisted hot water extraction method are the highest.The The galacturonic acid content of pectin in hot water extraction and enzyme-assisted methods was only 26.3%and 17.1%.3.The pectin oligosaccharides were synthesized by enzymatic hydrolysis of hawthorn pectin,and then the acidic sugars were separated and purified by ion exchange column to obtain the hawthorn pectin with the polymerization degree of 1-4,5-7 and 8-11,respectively.Glycans.The degree of polymerization in the 1-4 hawthorn pectin oligosaccharide was milky white,5-7 degree of polymerization of hawthorn pectin oligosaccharides as a beige powder,and the degree of polymerization of hawthorn pectin oligosaccharides in the 8-11 compared to 5-7 The degree of polymerization is a little deeper.Therefore,the main component of hawthorn pectin is polygalacturonic acid.4.Effect of hawthorn pectin oligosaccharides on the storage properties of milk powder:1)During the accelerated storage of milk powder at 65?,the a_w of blank control group,FOS control group and sample POS(5-7)group,sample POS(8-11)did not change significantly,showing first decreased and then increased slightly.At the 28th day,The a_w of FOS control group,the sample POS(5-7)group and the sample POS(8-11)group were all around 0.17.In the sample POS(1-4)group,the a_w value increased rapidly from the 14th day,and the a_w reached 0.28 at the end of the experiment.2)After 4 weeks of accelerated storage of milk powder at 65?,its color has been deepened to varying degrees.The Hunter b values??of blank control group,FOS control group,sample POS(5-7)group and sample POS(8-11)group increased slightly.The Hunter b value of the sample POS(1-4)group increased rapidly from the 14th day,and the Hunter b value reached 15.03 at the end of the experiment.3)With the prolongation of storage time,the fluorescent intensity of fluorescent substances in milk powder increased.Among them,the fluorescence intensity of the POS(1-4)group increased the fastest,which was significantly higher than that of other groups in the same period.At the end of the experiment,the fluorescence intensity of sample POS(1-4)group was 86.23,an increase of 427.08%compared with before accelerated storage;the blank control group was 35.44,an increase of 115.83%;FOS control group was 46.32,an increase of 200.19%;The sample POS(5-7)group was 24.14,an increase of 35.01%;the sample POS(8-11)group was 28.55,an increase of 85.15%.During the entire accelerated storage period,the order of fluorescence intensity increase was POS(1-4)>FOS control>blank control>POS(8-11)>POS(5-7).Thus,the samples POS(5-7)and POS(8-11)have a strong inhibitory effect on fluorescent AGEs in infant formula milk powder,while POS(1-4)and FOS are fluorescent in infant formula milk powder.The generation of AGEs has a promoting effect.In summary,we took hawthorn as the research object,optimized the extraction process of pectin polysaccharides,improved the quality of pectin finished products,and analyzed the components of hawthorn pectin prepared after optimizing the extraction methods for its reference in food applications.In the storage experiment of milk powder,the high degree of polymerization of hawthorn pectin oligosaccharides has significant anti-glycation activity.The results of this study provide a scientific basis and a new direction for the development of new antioxidants based on pectin oligosaccharides. |
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