Study On The Preparation And Characteristics Of Microencapsulated Rice Antioxidant Peptide

Rice antioxidant peptides becomes a research focus because of its excellent properties in small molecular weight,safety,antioxidant activity and absorption.But rice antioxidant peptide stability is poor,easily affected by many other extrinsic factors such as oxygen, temperature, humidity,and easily degraded by gastric acid and pepsin,leading to low bioavailability with oral method,which greatly restricted the application of antioxidant peptides in food,medicine and other fields.Microencapsulation is one of commonly technique in the food industry by protecting the core materials from environments.This paper adopted piercing method and double-layer embedment to produce rice antioxidant peptide microcapsules,and studied their preparation process,physical and chemical characteristics,the properties of storage and controlled-release.The results showed as follows:(1)Using sodium alginate as capsule material,calcium chloride solution as liquid solidifying,preparation of rice antioxidant peptide microcapsule by piercing method was investigated,results showed that the optimum parameters were as follows:the mass ration of essence to coat0.3,sodium alginate concentration1.4%,operating temperature50℃,calcium chloride concentration1.8%,emulsifier concentration0.26%.The encapsulation efficiency could reach as high as81.24%under the above-mentioned optimum conditions.(2)Rice antioxidant peptide was primarily microencapsulated in corn porous starch and then embedded in xanthan gum with ultrasound-assisted, results showed that the optimum parameters were as follows:ultrasonic time30min,ultrasonic power150W,the mass ratio of peptide to porous starch3:12,solid substance content18.0%,xanthan gum amount0.5%.The encapsulation efficiency could reach as high as80.12%under the above-mentioned optimum conditions.(3)The moisture content of microcapsules which were produced by piercing method and double-layer embedment were3.04%and2.21%, two kinds of microcapsules are suitable for long-term storage because of their respectively low moisture content.The repose angle was42.2°and47.5°,description mobility is good,and the microcapsules which were produced by piercing method have higher mobility,compared to the double-layer embedment method.The results of scanning electron microscopy photographs showed that:surface structure of two kinds of microcapsules remain complete,and both of their form are uniform.It indicated that the shell have good protective effect to core material.The results of infrared spectrogram showed that:find no rice antioxidant peptide characteristic absorption peak,and no new chemical bond in two kinds of microcapsules.It indicated that the embedding effect is good.(4)Glass transition temperature(Tg) of piercing method and double-layer embedment to produce two rice antioxidant peptide microcapsules by differential scanning calorimetry (DSC) indicated was at59.558℃and55.558℃,which indicated the storage stability was good and can be used widely,because both of the encapsulation products were at the glass state in normal temperature storage(25℃).The analysis result of TGA revealed that:the method of piercing and double-layerembedment to prepare microcapsules could raise the thermal degradation temperature effectively for rice antioxidant peptide from300℃to480℃and340℃.So they have very good protection effect for core material.The rice antioxidant peptide microcapsules which were produced by piercing method have higher storage stability and high temperature stability,compared to the double-layer embedment method.(5)The experiment showed that the embedded peptide had better antioxidant activity than which was not embedded at room temperature for30days.The test showed that microencapsulation was a good method for improving the stability of antioxidant peptide.microcapsules which were produced by piercing method had higher antioxidant activity than double-layer embedment method.(6)The controlled-release properties of microcapsules showed that:the cumulative release amount of two kinds of micro spheres was low in the gastric fluid,these microspheres could continue to release in the intestinal juice.So it delayed release time and avoided the trouble of taking medicine frequently.The microcapsules which were produced by piercing method have better slow-release effect.The release data of two kinds of microcapsules in gastric and intestinal fluids were fitted with zero order release equation,first order release equation and Higuchi equation.The results showed that the release data of microcapsules which were produced by piercing method conformed with the zero order release equation in gastric and intestinal fluids;the release data of microcapsules which were produced by double-layer embedment conformed with the first order release equation in gastric juice,and the release data in intestinal juice conformed with the zero order release equation.