Study On The Stability Of Main Active Components Of Mulberry And Preparation Of Anthocyanin Microcapsules

Mature mulberry contains a variety of active substances,of which the most abundant are flavonoids,anthocyanins and polysaccharides.The stability of flavonoids,anthocyanins and polysaccharides of mulberry was studied in this paper.The anthocyanins were further purified,identified and microencapsulated.The main conclusions are as follows:The extracting conditions of flavonoids from mulberry were as follows:adding 1:10（m:v）of 60%ethanol and extracting for 120 min,ultrasonic power 150 W.The resultant flavonoid yield was 5.56±0.96 mg/g,purity was 4.62±0.31%.The extracting conditions of anthocyanins were as follows:a 90-minute extraction time,10 mL/g solvent to solid ratio and 40%acidified ethanol concentration（including 0.1%HCl）,ultrasonic power 150 W.The resultant anthocyanin yield was 2.91±0.10 mg/g,purity was 4.83±0.25%.Polysaccharides were extracted by hot water extraction and alcohol precipitation:a 1-h extraction time,90 ℃ temperature,5 mL/g solvent to solid ratio.The resultant polysaccharide yield was 2.39 ±0.04 mg/g,purity was 44.46±0.65%.The results of stability study showed that the effect of temperature on anthocyanin was greater than that on flavonoids and polysaccharides;Oxidant had influence on all three active components;pH had little effect on polysaccharides,flavonoids are more suitable for preservation under weak acid conditions,while anthocyanins are more suitable for preservation under strong acidic conditions.;Cu+、Cu²⁺、Fe²⁺、Fe³⁺ and Al³⁺ have destructive effects on flavonoids and anthocyanins;All three active substances should be avoided exposure to bright sunlight.Baseselected as the purified filler from macroporous resins HPD600,D101,LX1180,d on the adsorption and desorption rates,HPD600 resin was AB-8,and DA201-C.The purified product was purple black powder with a color value of 56.1,a sugar removal rate of 67.6%and a purity of 71.4%.The relative content of cyanidin-3-O-glucoside in purified samples was about 41.2%by HPLC analysis.Mass spectrometry analysis showed that the purified sample contains at least 7 monomers:kaempferol-3-O-rutinoside,cyanidin-3-O-glucoside,cyanidin-3-O-rutinoside,rutin,quercetin-3-O-β-D-glucopyranoside,resveratrol and quercetin.Compared with unpurified anthocyanins,the effect of temperature and oxidant on the anthocyanin after purification was reduced;pH value and metal ions had greater influence on the anthocyanin preservative rate,while the color change was less than that before purification;the purified anthocyanins become more sensitive to light.The storage and processing of mulberry anthocyanins should be carried out at low temperature,light avoidance,low pH,and avoid contact with copper and iron ions.The results of response surface optimization showed that the best technology for preparing mulberry anthocyanin microcapsules by spray drying was as follows:using maltodextrin and Arabic gum as wall materials,the mass ratio of the two materials was 8.58:1,the ratio of wall to core was 9.62,the inlet air temperature was 145.68 ℃,and the predicted embedding rate was 92.59%.In order to facilitate the practical operation,the parameters were modified as follows:the mass ratio of the two was 8.6:1,the wall-core ratio was 9.6%,the air inlet temperature was 146℃ and the actual embedding rate was 91.61±0.63%.The mulberry anthocyanin microcapsule product was red powder with water content of 7.59 ±0.10%and solubility of 99.49 ±0.42%.Scanning electron microscope observation showed that the appearance of the product was spherical,without wall breaking,the surface appeared fold and depression.The results of storage stability of anthocyanin microcapsules showed that anthocyanin microencapsulated was hardly affected by light,but oxygen had a great effect on the stability of anthocyanins.Therefore,microencapsulated anthocyanins still need to be sealed to avoid exposure to oxygen.