| Curcumin is a natural pigment extracted from turmeric,with nutritional,medical and physiological functions.But due to its poor solubility in water,poor stability to light,heat and oxygen,and low utilization limits the application of curcumin in the food industry.Protein or protein-polysaccharide based nutraceutical delivery system,which can improve physicochemical stability,water solubility,targeting property and sustained release of bioactive components in foods,has been attracted more attention during the past few years.In this study,the lotus seed protein is first used to construct the Lsp-Cur(lotus seed protein and curcumin)and Lsp-Cur-Pec(lotus seed protein and curcumin and pectin)complex emulsification system,and the physical,chemical stability,antioxidant and release in vitro and the application in noodle processing of the two systems have also been studied.The main results of this study are as follows.1.Firstly,optimum technological parameters for construction of the Lsp-Cur and LspCur-Pec composite emulsion systems had been determined by single factor experiments(such as the lotus protein concentration,oil phase water ratio,ball milling time,pectin concentration,pectin and protein-curcumin emulsion volume ratio),and followed by orthogonal experiments,for the preparation of Lsp-Cur compound emulsifying systems:lotus protein concentration was 50 mg/mL,oil phase aqueous phase was 8%,milling time was 8 h.On this condition the embedding rate of curcumin in Lsp-Cur compound emulsifying system was 82.65%.For the preparation of Lsp-Cur-Pec compound emulsifying systems:lotus protein concentration was 50 mg/mL,oil phase aqueous phase was 8%,milling time was 8 h,pectin concentration was 3 mg/mL.On this condition the embedding rate of curcumin in Lsp-Cur-Pec compound emulsifying system was 87.02%.These results indicated that pectin had acceleration on embedding of curcumin by lotus seed protein.In order to facilitate storage and application,the Lsp-Cur and Lsp-Cur-Pec composite emulsions had been dried to composite particles by spray drying method.2.The exterior evaluation results of the two kinds of curcumin composite particles showed that the curcumin composite particles were grass yellow powder with fine and uniform particles,no impurities,no odor and no sticky wall.The solubility of two kinds of composite particles was above 75.15%and 81.39%,respectively,but the solubility of free curcumin was only 6.27%,which indicated that Lsp-Cur and Lsp-Cur-Pec both greatly improves the solubility of curcumin(p<0.05).The FT-IR results showed that the phenol ring of the curcumin and the hydrophobic cavity of the protein was combined by hydrophobic force to achieve the purpose of protecting curcumin.The CD results showed that the relative content of ?-helix of lotus seed protein was decreased,and the relative content of ?-sheets was increased after embedding curcumin.DSC and X-ray could investigated the morphology of curcumin in composite particles,curcumin had a melting absorption peak at 183? and crystal peak on the X-ray diffraction pattern.However,the melting point of curcumin in the composite particles did not appear and there was no crystal peak on the X-ray diffraction pattern of composite particles.The peak shape indicated that the curcumin in the composite particles was an amorphous state.3.The results also showed that Lsp-Cur-Pec composite particles exhibited good stability in high temperature,high ionic strength and different pH conditions,and protect curcumin with sunlight exposure.After 25 h UV irradiation,the absorbance of curcumin decreased by 89.82%,while the absorbance of Lsp-Cur and Lsp-Cur-Pec composite particles decreased by 61.33%and 61.34%,which indicated that the light stability of curcumin increased by 28%.The content of free curcumin decreased to 34.16%at high temperature,and the retention rates of Lsp-Cur and Lsp-Cur-Pec were 46.41%and 54.01%,which increased 1.34 times and 1.58 times respectively.pH stability experiments showed that Lsp-Cur-Pec composite particles could improve the stability of Lsp-Cur composite particles near the isoelectric point of the protein.Storage stability experiments showed that the two curcumin composite particles were still very stable after 30 days of regular temperature storage with strong stability.Antioxidant experiments showed that the ability to remove DPPH and O2-·significantly increased(p<0.05).The experiment of simulating human gastrointestinal tract found that in gastric digestion stage,the release rate of curcumin in Lsp-Cur composite particles was only 20.01%,and the release rate of curcumin in Lsp-Cur-Pec composite particles was only 19.43%.However,the bioavailability of free curcumin after incubating in the intestinal fluid for 180 min was only 14.84%,while the bioavailability of Lsp-Cur and Lsp-Cur-Pec composite particles was as high as 63.04%and 74.06%,respectively.After digestion,the utilization rate of curcumin in composite particles was 4.99 times than free curcumin,which fully showed that curcumin in the composite particles could be more efficiently released into the digestive juice and absorbed by the body.4.Adding proper amount of curcumin compound particles could significantly improve the cooking quality of the noodles,and noodles could easily maintain a good appearance during the cooking process;The addition of curcumin compound particles could increase the hardness,elasticity and chewiness of the noodles,and give noodles a bright yellow color.Compared to the Lsp-Cur-Pec composite particles,the Lsp-Cur composite noodles had a higher chroma and sharper color;The overall sensory scores of the two composite noodles were 83 and 84 respectively with best reception by consumers.Curcumin could enhance the oxidative stability of noodles.During storage,the low moisture content of Lsp-Cur and Lsp-Cur-Pec composite noodles could increase the storage stability of noodles,curcumin composite particles could retard the decrease of noodle pH and inhibit the rancidity of oils;The curcumin composite particles noodles had relatively slow oxidation,the Lsp-Cur and Lsp-Cur-Pec composite particles inhibited the oxidation of noodles and the stability was increased by 1.155 times and 1.158 times respectively.Adding a certain amount of Lsp-Cur and Lsp-Cur-Pec composite particles to noodles could boss play a role in delaying the oxidative rancidity.The two composite particles could improve the oxidation stability of noodles effectively which the amount is only 0.02%. |
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