Study On Pigment And Pectin From Pitaya Peel

Pitaya peel, as a by-product of the processing of pitaya, used to be abandoned. In fact pitaya peel is rich in nutrients, such as organic acids, protein, pigment and pectin. Research and development of pitaya peel, can not only improve the utilization ratio of nature resources, but also improve additional value of pitaya.This paper taked pitaya peel as experimental material, optimized the extraction technology, studied the physical and chemical properties of pigments and pectin. And the antioxidant activity of pigment was also discussed. The research aimed to provide technical support for the development, utilization and processing of pitaya peel. The main results were as follows:1. Research about extraction technology, physical and chemical properties and antioxidant activity of red pigment from pitaya peel(1) Study on extraction technology of pigmentTaking fresh pitaya peel as raw material, the extraction technology of red pigment from pitaya peel by solvent extraction method was studied. The results of the optimizing pigment extraction technology showed that the proper extraction solvent was pure water, ration of solid to liquid was 1:7, the temperature was 30℃, and extracted twice,30 minute each time.(2) Study on physical and chemical properties of pigmentThe natural pigment extracted from pitaya peel was a kind of water soluble pigment, and the ability in light and heat. Performance of pigment was more stable in 5-8.Appropriate addition of sugar (glucose, sucrose, starch) had no remarkable effect on pigment, high concentration of sugar had certain effect on pigment; Sodium benzoate and citric acid had certain effect on the pigment; NaCl had no significant effect on pigment; In metal ions, K+, Ca2+had little influence on its stability, while Cu2+, Fe3+, Al3+had a significant impact on its stability.(3) Study on antioxidant activity of pigmentThe antioxidant activities of pigment were determined by four methods, all the results show that pigment had activity of antioxidant from pitaya peel. Trolox served as a control for antioxidant activity. The antioxidant activity testing by four methods(DPPH, ABTS, FRAP, ORAC) are 93.6 mg Trolox E/g,90.4mg Trolox E/g,105.lmg Trolox E/g,84.7 mg Trolox E/g。2. Study on the extraction technology, physical and chemical properties of pectin from pitaya peel(1) Study on extraction technology of pectinThe extraction technology of pectin in pitaya peel was investigated via acid method. The results showed that the optimal extraction conditions were following:the ratio to liquid was 1:7, extracting pH was 2.0, extracting temperature was 90℃, and the extracting time was 90 min. The extraction efficiency of pectin at this optimal extraction can arrive at 91.58%, and the yield of pectin is 2.34%(±0.07). The extracting volume of pectin is ample.(2) Study on physical and chemical properties of pectinThe pectin was prepared under optimized the extraction process, its purity was 60.4%, the degree of esterification was 29.57%, indicating that the pectin belongs to low methoxyl pectin. The weight-average molecular weight of pectin was 87166, and the number-average molecular weight of which was 59137, which indicated that it belonged to relatively small molecular weight pectin. The viscosity of pectin was affected by multi-factors. Pectin viscosity enhanced with the concentration of pectin increasing; The higher the temperature, the lower pectin viscosity was; With increasing pH and Ca2+, the pectin viscosity first increased and then decreased; The pectin viscosity decreased with the extension of resting time at the temperature 95℃; The pectin also had certain oil absorption and emulsifying ability.