Microencapsulation And Application Of Red Pigment Of Pitaya Fruit

The red pigments contained in pitaya is bright in color and has strong coloring potential and health care function,so it is an ideal substitute for synthetic pigment.However,the red pigment is unstable in nature and is easily affected by external factors such as light,heat and p H.In order to improve the stability of pitaya red pigment,spray drying technology was used to embed it in this paper,which provided theoretical basis for further development and utilization of pitaya red pigment.The experimental methods in this paper were as follows:1.Study on preparation technology of pitaya red pigment microcapsulesUsing red pigment as core material,gelatin,gum arabic,maltodextrin and soluble starch as single wall material or composite wall material,microencapsules were prepared by spray drying technology.Through single factor experiments,water content,chromaticity,the embedding yield and efficiency were determined to select the best wall material.Then,the optimal preparation process conditions of pitaya red pigment microencapsules were determined by orthogonal test.2.Characterization and stability of pitaya red pigment microencapsulesPitaya red pigment microencapsules were prepared and characterized on the basis of the above optimized experiment.Firstly,the embedding rate,water content and color difference of the red pigment were determined.Then,the physical and chemical properties of the red pigment and its microencapsulation were studied by scanning electron microscope(SEM),UV-Vis absorption spectra,fourier transform infrared spectrometer(FTIR),high performance liquid chromatography(HPLC),X-ray diffraction(XRD),differential scanning calorimetry(DSC)and other technologies.Finally,its storage stability and in vitro digestion characteristics were studied.3.Evaluation of gastrointestinal absorption characteristics of microencapsules and biological activity of pitaya red pigmentTo study the gastrointestinal absorption of pitaya red pigment and microcapsules,HPLCMS was used to analyze its components and observe its changes.The antioxidant,antibacterial and toxic activities were further analyzed.4.Prepare and evaluating pitaya red pigment productRed pigment was added to the preparation process of lipstick and yogurt,and these products were evaluated to understand their application prospects in cosmetics and food fields.The experimental results in this paper were as follows:1.Study on preparation technology of pitaya red pigment microencapsules.Through single factor experiments,maltodextrin was selected as the wall material,and the ratio of core material to wall material was 1: 4.On the above condition,the spray drying process conditions were explored: the optimal temperature was 150 �C in the inlet temperature range of 120 ? 160 �C,the optimal speed was 5.2 m L/min in the peristaltic pump range of 1 ? 3,and the optimal speed was 0.46 m3/min in the fan speed range of 3 ? 5.Through orthogonal optimization experiments,the optimum experimental conditions were determined as follows: inlet temperature,fan speed and peristaltic pump speed were150 �C,0.42 m3/min and 6.7 m L/min,respectively.2.Characterization of pitaya red pigment microencapsules and their stability experiments.On the basis of optimized wall materials and spray drying conditions,four antioxidant microencapsules were prepared by adding ascorbic acid.HPLC,UV-vis and FTIR characterization results showed that the properties of pitaya red pigment did not change before and after microencapsulation.FTIR,XRD and DSC analysis confirmed that the red pigment was successfully embedded in microencapsules.The results of stability test showed that the stability of maltodextrin microcapsules added with ascorbic acid had relatively good stability under different light and temperature;and the degradation of red pigment stored in low temperature and far away from light was relatively slow.All the above results indicated that microencapsulation could effectively improve the stability of red pigment,and the addition of ascorbic acid in maltodextrin microencapsules could further improve its stability,which had great application prospects in food,cosmetics and other fields.3.Evaluation of gastrointestinal absorption characteristics of microencapsules and biological activity of pitaya red pigment.The results of in vitro digestion experiments showed that only a small part of the pigment was absorbed,and most was excreted out of the body through feces and urine.Antibacterial experiment results showed that pitaya red pigment had no significant antibacterial effect.DPPH results showed that there was no obvious difference between spray drying and freeze drying on the antioxidant effect of pitaya red pigment,so spray drying technology could be applied to the preparation of pitaya red pigment microencapsules.Pitaya red pigment contained 7 betain components,namely malonoglycoside,betain,isopropane betain,isobetain,unknown ?-anthocyanin,unknown propane betain and butyrylbetain by HPLC-MS analysis,of which propane betain was the largest component,followed by betanin.Pitaya red pigment was non-toxic to aquatic organisms and would not cause environmental pollution by ECOSAR program prediction.Therefore,it could be applied in the fields of food and cosmetics.4.Prepare and evaluating pitaya red pigment productThe application of pitaya pigment in lipstick and yogurt products showed that the application of pitaya pigment in lipstick alone was not good,but it could give yogurt a unique and stable color.To sum up,pitaya red pigment obviously improved its stability after microencapsulation,of which maltodextrin microencapsulation with ascorbic acid had the best effect and was expected to be applied in food and cosmetics fields.