Extraction And Emulsifying Properties Of Pectin From Persimmon Peel

Diospyros kaki Thunb belongs to the Diospyros.kaki.L plant of the Ebenaceae family.It is a characteristic fruit in China and has good edible and medicinal value.In the food processing field,persimmon fruits are mainly fresh foods,persimmons,persimmon fruit wine,etc.,and their processing by-products are mainly persimmon skins.Pectin is a natural polysaccharide that exists in plant cell walls and medium gum layers.It has a variety of functional properties and physiological activities.It has been widely used in the fields of food,medicine and cosmetics.In order to improve the added value of persimmon products and the comprehensive utilization of by-products,this study uses persimmon peel as the raw material,and optimizes the pectin extraction method through response surface experiments,compares the physical and chemical properties of persimmon peel with commercial citrus pectin.The cause of emulsification of persimmon peel pectin was discussed,and it was used as an emulsifier in the preparation of emulsion.The main experimental results are as follows1.The process of extracting persimmon peel pectin by acid extraction was discussed.Based on the results of single-factor experiments,using Box-Behnken Design(BBD)design to optimize the pectin extraction process,the best extraction conditions for the obtained persimmon peel pectin are: material-liquid ratio of 1: 20,extraction temperature of 90?,the extraction time was 120 min,the extraction solution was pH 1 and the extraction solvent was hydrochloric acid.Under these conditions,the extraction rate of persimmon peel pectin was 4.26 ? 0.25%.2.The differences of basic physical and chemical properties between persimmon peel pectin and commercial citrus pectin were compared and analyzed.The Gal A content of persimmon peel pectin and commercial citrus pectin were 71.39 ? 0.32% and 77.65 ? 0.48%,respectively.The degree of esterification was 41.97 ? 0.22% and 75.34 ? 0.85%.Nuclear magnetic resonance spectrum and fourier transform infrared spectroscopy analysis showed that persimmon peel pectin was acetylated low-methoxy pectin,and commercial citrus pectin was high-methoxy pectin.The PDI of persimmon peel pectin(5.70 ? 0.08)is lower than that of commercial citrus pectin(6.19 ? 0.02),indicating that the molecular weight distribution of persimmon peel pectin polymer is narrower.According to the measurement results of monosaccharides,the RGI ratio of both pectins is very low,but the ratio of persimmon peel pectin(1.28 ? 0.01)is higher than that of commercial citrus pectin(1.00 ? 0.05),indicating the branching area of persimmon peel the proportion is high.SEM images showed that the surface of the persimmon peel pectin was rough,the surface of the commercial citrus pectin was fluffy and smooth,and the XRD spectrum showed that both pectins were amorphous.Comparing the thermodynamic properties of the two pectins,the maximum exothermic peaks of persimmon peel pectin and commercial citrus pectin in DSC images appear at 248.26? and 241.76 ?,respectively,indicating that the thermal stability of persimmon peel pectin is better.3.Study on the technology of preparing persimmon peel pectin.The persimmon peel pectin was prepared under the conditions of 1.5% concentration,65% oil phase fraction,and 2% concentration,50% oil phase.The emulsion remained stable after standing for 30 days,indicating that it has good emulsifying ability.Rheological results show that both pectins are pseudoplastic non-newtonian fluids,persimmon peel pectin has significant shear thinning characteristics,and commercial citrus pectin exhibits stronger shear resistance.Compared with the pectin solution,the viscosity of the emulsion increased significantly,and the viscosity of PPE was lower than that of CPE.4.Study on the antioxidant properties of emulsions.The antioxidant properties of persimmon peel pectin,commercial citrus pectin and commercial apple pectin were compared.It was found that the antioxidant properties of persimmon peel pectin were significantly higher than the other two,and the total antioxidant activity was 3 times that of commercial citrus pectin.The changes of MDA content in PPE-1.5%(50%),CPE-1.5%(50%)and corn oil alone were analyzed.The change curve of CPE-1.5%(50%)was similar to corn oil,but PPE the MDA content in PPE-1.5%(50%)was significantly suppressed.