| Auricularia auricula is the second most widely used edible fungus in China.As a valuable medicinal and food glial fungus,it has high nutritional value and health effects,and is also one of the world’s recognized natural health foods.Auricularia auricula and its fruiting body are rich in a variety of nutrients.Among them,the active components of polysaccharides have a wide range of biological activities,such as antioxidant,anticoagulant,hypoglycemic,anti-tumor,anti-inflammatory,and immune-enhancing activities,and are often used in dietary supplements and functional foods.However,the research on the emulsification of Auricularia auricula polysaccharide(AAP)is still missing.Emulsion is a carrier used to encapsulate,deliver and release bioactive ingredients,which is widely used in the food field.Its stability is mainly affected by factors such as the type of emulsion.Natural macromolecular polysaccharides are often used as emulsifiers to stabilize oil-in-water emulsions,and the extraction methods of polysaccharides affect the emulsification properties.Therefore,in this study,three kinds of Auricularia auricula polysaccharides(AAP-W,AAP-A and AAP-AL)were obtained by different solvent extraction methods,and their physicochemical properties and emulsification properties were characterized and analyzed.The AAP-W with the best emulsification property was selected to prepare oil-in-water emulsion.In addition,the effects of polysaccharides concentration,oil-water ratio,p H and salt ion concentration on emulsion stability were investigated.AAP-W emulsion loaded with β-carotene was constructed,and its storage stability,digestive stability,and retention of β-carotene were studied.The main contents and research results are as follows:(1)Three kinds of AAP were obtained by hot water extraction method,hot acid extraction method and hot alkali extraction method,and their physicochemical properties were investigated.The study found that different extraction methods had no significant effect on the glycosidic bonds and main functional groups of AAP,and the monosaccharide types,thermodynamic properties and crystallinity of the three polysaccharides were basically the same.However,different extraction methods had significant effects on the chemical composition,monosaccharide composition,molecular weight and morphology of the polysaccharides.Among them,AAP-W had the highest total sugar content,protein content and molecular weight,and its wetness was the most close to neutral.(2)The emulsifying properties of three kinds of AAP and the rheological properties of the emulsions were determined,and the appearance,micromorphology and particle size potential of the emulsions were observed and measured.Among the three polysaccharides,AAP-W was found to have the best emulsification activity and emulsification stability,the smallest emulsion particle size,the most uniform droplet dispersion,and the highest gel strength and viscoelasticity.(3)The effects of different polysaccharides concentrations and oil-water ratio on the stability of the emulsion were investigated,and the p H stability and salt ion stability of the emulsion were measured.The results showed that when the polysaccharide concentration was above 1%,no phase separation occurred and the emulsion could maintain a stable state for a long time.When the volume fraction of oil phase reached 0.6,the emulsion was stable and no demulsification occurred.The concentration ranges tested for p H and salt ion stability(p H: 3-11,Salt ion concentration: 0 mm-500 m M).Although the particle size of the emulsion changed,it remained stable.The results showed that the optimum polysaccharides concentration and oil phase volume fraction of AAP-W emulsion were 1% and 0.5,respectively.The emulsion could maintain good stability under harsh environment(strong acid,strong alkali and high salt ion concentration).(4)The emulsion loaded with β-carotene was constructed,and the storage stability and digestive stability of the emulsion and the retention rate of β-carotene at different temperatures were determined.The study showed that the AAP-W emulsion loaded with β-carotene had good stability.The emulsion system has a protective effect on β-carotene,which can significantly delay its decomposition and improve its bioaccessibility and digestive stability. |
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