Study On Optimization Of Extraction Of Persimmon Pectin And Its Physical And Chemical Properties

Mopan persimmon is rich in pectin,which is a good pectin resource.Because pectin has high medicinal value and nutritional value,it is in short supply in domestic and foreign markets.Acid electrolyzed water has a very low pH value,which is mainly used for sterilization in food industry.At present,it has been applied to the extraction of residual oil,and has achieved certain results.In this paper,the application of acid electrolyzed water in pectin extraction has been carried out,which provides a theoretical basis for the extraction of pectin and the application of acid electrolyzed water.In this paper,the persimmon dregs from the ground plate after vinegar brewing are used as raw materials,acid electrolyzed water is used as solvent,and the extraction rate is used as index.Through the single factor and response surface design test,the optimal parameters of water bath extraction and ultrasonic assisted extraction are optimized.On this basis,the physical and chemical properties,rheological properties and emulsification of pectin in different extraction methods of traditional water bath(CH),electrolytic water bath(AEW)and ultrasonic assisted electrolytic water(AEWU)were analyzed and compared.The main conclusions are as follows:(1)The optimum conditions of extracting pectin from persimmon dregs with electrolyzed acid water are: pH 1.6,temperature 85.4?,time 79 min,the predicted value of the optimized extraction rate 5.705%,which is close to the experimental result of5.678%.(2)Further development showed the optimal conditions of extracting pectin from persimmon residue by ultrasonic assisted acid electrolyzed water were: temperature 80?,59 min,ultrasonic power 400 W,the predicted value of the optimized extraction rate12.184%,which was close to the experimental result 12.134%.(3)The physical and chemical properties of three kinds of pectin,AEWU-P,AEW-P and CH-P,were studied.The effects of different extraction methods on the structure of persimmon pectin were studied by analyzing esterification degree,galacturonic acid,molecular weight and monosaccharide.The results showed that CH-P had the highest degree of esterification(97.64%),followed by AEW-P(95.1%),and AEWU-P had the lowest degree of esterification(90.58%).The content of galacturonic acid has the same trend as esterification degree,namely 85.39%,70.47%,66.52%.Galacturonic acid andesterification degree showed significant differences.The monosaccharide types of the three kinds of pectin are the same,but the contents are quite different.The total sugar content of AEW-P was the highest(63.320%),followed by AEWU-P(38.298%),then CH-P(35.884%).The purity of pectin was high by FTIR.The results of UV scanning showed that both electrolyzed water and ultrasound could affect the physical and chemical properties of pectin.The effects of different extraction methods on the rheological properties of pectin solution were studied.The apparent viscosity of the three kinds of pectin solution is between 1.5965 and 4.3210 mPas;the apparent viscosity of the emulsion are between 41.9708 and 157.7828 mPas,and the order is CH-P>AEWU-P>AEW-P.The apparent viscosity of the emulsion under the same conditions is greater than the apparent viscosity of the solution.All of the three kinds of persimmon pectin conform to the power-law model.It was found that the properties of persimmon pectin were closer to Newton fluid,which corresponded to the molecular weight of three kinds of persimmon pectin.The molecular weight of three kinds of persimmon pectin from 60.8 to 67.5 kDa,which is lower than that of common pectin such as citrus and apple.The results of microscopic observation,particle size distribution and stability of pectin emulsion showed that the distribution of three kinds of pectin emulsion particles was homogeneous and the emulsion property was good,and the stability of emulsion was good with the prolongation of storage period.