Study On Extraction And Drying Technology Of Pectin From Premna Puberula Pamp

In this study,the extraction technology of pectin from leaves was established by using Premna puberula as the experimental material.On this basis,the physical and chemical properties,structure,biological activity and drying technology of pectin obtained by different extraction methods were studied.The main results are as follows:The range of each factor was determined by single factor test,and then the key factors affecting pectin yield were screened by Plackett-Burman experimental design.Finally,the ultrasonic-assisted acid extraction of pectin from leaves was optimized by response surface method.The results showed that the key factors affecting pectin extraction were p H value,ratio of liquid to material,ultrasonic power and reaction time.The optimized process parameters are p H 1.9,liquid-to-material ratio 12.5,ultrasonic power 450 W,reaction time 95 min,ultrasonic time 10 min,reaction temperature 85℃.Under these conditions,the yield of pectin is 11.53%.The conditions of inactivating enzyme in leaves were explored by orthogonal experiment.The results showed that the primary and secondary order of the factors affecting microwave inactivation was as follows: microwave time had the greatest influence,followed by leaf quality and microwave power,and the best extraction technology was leaf mass 10 g,microwave power420 W,microwave time 60 s,and the effect of microwave inactivation was the best.Through the optimal condition verification test,the minimum enzyme activity was 22.72 μg min-1·g-1.Pectinase extraction from leaves was optimized by response surface method.The results showed that the optimum conditions were as follows: enzyme amount 82 U/g,ratio of liquid to material 18:1,reaction time 65 min,reaction temperature 55℃,reaction p H 5.5.Under these conditions,the yield of pectin was 7.81%.The effects of different extraction methods on the physical and chemical properties,structure and biological activity of leaf pectin were studied.the results showed that the pectin extracted from leaves was highly esterified pectin,and the extraction rate of UAAE pectin(11.53%)was significantly higher than that of AE(10.24%),MAEE(9.89%)andEE(7.81%).The galacturonic acid content of pectin obtained by different extraction methods was high and there was no significant difference,among which EE(82.05%)and MAEE(81.61%);MAEE had the best emulsifying property and gel quality.the results of infrared spectrum and monosaccharide determination showed that different extraction methods had no significant effect on the chemical structure and monosaccharide composition of pectin.The in vitro hypoglycemic and antioxidant activities of the pectin extracted by the four methods were dose-dependent,among which the activity of MAEE was the strongest.Different drying methods had significant effects on the pectin properties of leaves,and the effects on each index were also different.Based on the comprehensive consideration of pectin purity,esterification degree,rehydration,color and unit energy consumption,the equipment required for blast drying is simple,but the pectin quality is poor and the energy consumption is high;vacuum freeze drying is of the best quality,but the equipment required for vacuum freeze drying is expensive and time-consuming;vacuum drying equipment is relatively simple,easy to operate,relatively low energy consumption and good product quality,which is suitable for the industrial application of pectin drying of P.puberula leaves.