Microencapsulation Of Henna And Gallnut Pigment For Enhanced Safety And Stability

Plant hair dyes are favored by many consumers because of their natural,green,ecofriendly nature and other health benifits.However,as natural pigments,plant dyes are vulnerable to environmental factors such as light,heat and p H,which limit its application in cosmetics.Microencapsulation technology has many advantages,such as protecting core material,improving stability and reducing toxic and side effects.It is widely used in food,medicine,textile and other fields.In this paper,henna(Lawsonia inermis L.)and Chinese gallnut(Rhus chinensis Mill.)were prepared by spray drying.Two kinds of plant pigments were microencapsulated in order to improve the safety of henna and the stability of gallnut formulation.At the same time,after microencapsulated of henna and gallnut pigment,the physical and chemical properties,in vitro safety,storage stability,dyeing effect and stability of hair were systematically investigated.The main results are summarized as follows:In the study of henna pigment: 1)henna pigment microcapsules were prepared by spray drying method,and the drug loading was used as the evaluation index.The optimum embedding conditions were obtained by single factor and orthogonal test as follows:core-wall ratio 1:2,wall-material ratio 2:8(maltodextrin : gum arabic powder),and the inlet temperature was 180?.2)The in vitro safety evaluation showed that the cytotoxicity of henna pigment microencapsulated to human keratinocytes decreased by 2.85 times,the eye irritation decreased from severe to moderate,and the hair dye had no eye irritation.Before and after microencapsulation,they were non-skin irritating and skin sensitizing substances,but the sensitization decreased from medium reactivity to weak reactivity after microencapsulation.Therefore,microencapsulation can effectively reduce the toxic and side effects of henna pigment extract.3)The results of storage stability and color difference showed that the storage stability of microcapsules was better than that of unencapsulated henna pigment extract.4)The results of hair dyeing and its stability showed that henna microcapsule had good dyeing,coloring ability and good washing resistance.Henna pigment adsorption will damage hair scales,and the presence of ferrous ions will aggravate the damage degree of dyed hair,but henna pigment microencapsulation has a certain photoprotective effect,which can delay the photoaging of dyed hair.In the study of gallnut pigment: 1)gallnut pigment microcapsules were prepared by spray drying method,and the embedding rate was used as the evaluation index.The optimum embedding conditions were obtained by single factor and orthogonal test asfollows: core-wall ratio 1:6,wall-material ratio 0:10(maltodextrin: gum arabic powder),and the inlet temperature was 200?.2)The in vitro safety evaluation showed that gallnut pigment extract,microcapsule and its hair dye had no eye irritation.3)The results of storage and formulation stability showed that maltodextrin could be used as wall material to embed gallnut pigment and store it at 25 ?.4)The results of hair dyeing and its stability test showed that gallnut microcapsule had good dyeing effect and washing resistance.The adsorption of gallnut pigment will damage hair scales,and light will aggravate the damage degree of hair dye,but gallnut pigment can reduce the photodamage of hair dye,and the photoprotection effect after microencapsulation is more obvious.Taken together,microencapsulation can effectively improve the safety and storage stability of henna pigment,as well as to solve the instability of gallnut extract in alkaline formulation,thus promoting the commercial and industrial application of natural plant pigment in the field of hair dye cosmetics and meeting.The needs of consumers for natural,non-toxic non-oxidizing hair dye products.