| Alpha-linolenic acid diglyceride(ALA-DAG)is a functional oil with physiological functions such as reducing fat accumulation and preventing cardiovascular disease,and has important application value in the food field.Since ALA-rich is easily oxidized during storage and food processing,which affects product quality and causes loss of nutritional components,effective control of the oxidation of ALA-DAG is of great significance for its application in functional foods.In this study,the oxidative stability of ALA-DAG was improved by microencapsulation,and microcapsules with ALA-DAG as the core material were prepared.The structural characteristics,storage stability and in vitro digestion characteristics of the microcapsules were investigated.The main content as follows:(1)Study on preparation technology of ALA-DAG microcapsules.Taking emulsion stability and particle size as evaluation indicators,the optimal preparation process of ALA-DAG emulsion was explored by single factor experiment and response surface design optimization experiment.The results showed: the solid content was 50%,the oil load was 50%,the emulsifier compound mass ratio(glycerol monostearate: citric acid fatty acid glyceride)was 5:4,and the mass ratio of emulsifier to core material was 1:40,the stability of ALA-DAG emulsion was the highest,and the particle size of the emulsion was only 267.40 nm.The influence of different factors on the particle size of ALA-DAG emulsion was: oil-carrying content>the mass ratio of emulsifier to core material>solid content.The physicochemical properties of ALA-DAG microcapsules prepared with different compound wall materials were compared.It was found that when resistant dextrin and sodium caseinate were used as the composite wall materials,the physicochemical properties of the microcapsule was the best,the entrapment rate was 97.85±1.14%,the surface oil content was 1.06 ± 0.01%,and the moisture content was 2.60 ± 0.04%,the particle size of the reconstituted emulsion was 2.70±0.10 μm and had excellent dispersing properties.(2)Physicochemical properties and storage stability of ALA-DAG microcapsules.Fourier transform infrared spectroscopy confirmed that ALA-DAG and composite wall material formed ALA-DAG microcapsules structure,and the outside of ALA-DAG microcapsules was no obvious damage,the structure was complete,and the whole was spherical.The results of thermal stability analysis showed that the ALA-DAG microcapsules undergo thermal decomposition at 200 ℃,indicating that it had good heat resistance.The oxidation induction time of ALA-DAG microcapsules was 4.84±0.13 h,which was 2.61 times higher than that of ALA-DAG.Schaal oven accelerated oxidation experiments were performed on ALA-DAG microcapsules and monitored changes in peroxide value(POV),p-anisidine value(PV)and thiobarbituric acid value(TBARs)during storage.The results showed that the oxidative stability of ALA-DAG microcapsules was significantly improved compared with ALA-DAG.(3)In vitro simulated digestion studies of ALA-DAG microcapsules.Comparing the simulated digestion experiments of ALA-DAG microcapsules and ALA-TAG microcapsules in vitro,it was found that there was no significant difference in the release rate of the core material between the two,and both were about 85% at the end of the digestion process.The digested average particle size of ALA-DAG microcapsules was smaller than that of ALA-TAG microcapsules,and the fatty acid release rate(82.70 ±5.90%)and bioavailability(76.40 ± 2.29%)were greater than those of ALA-TAG microcapsules 76.20±6.40% and 70.30±3.87%.In general,ALA-DAG microcapsules had better digestion efficiency than ALA-TAG microcapsules and had good digestive properties. |
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