| Most probiotics have poor resistance and are easily inactivated by external oxygen,temperature,light and other environmental conditions during storage,processing and transportation.When ingested orally,probiotics microorganisms will undergo digestive enzymes,metabolites and microorganisms during gastrointestinal transportation.These factors can easily inactivate probiotics and affect their efficacy.Therefore,the nutrient loading system can be used to improve the survival rate of probiotics.C-phycocyanin is a bioactive nutrient with antioxidant and antiinflammatory effects.However,C-phycocyanin has poor stability and is easily inactivated by temperature,light and p H.At present,there are few studies on the construction of delivery system by mixing C-phycocyanin and polysaccharide.Therefore,this study used C-phycocyanin-polysaccharide mixture to construct a stable delivery system,to explore the stability of C-phycocyanin system and its effect on the survival rate of probiotics,to broaden the application range of Cphycocyanin,and to develop C-phycocyanin-based probiotic products.The main results are as follows:1.The potential,turbidity,microstructure and interfacial tension of Cphycocyanin-chitosan mixture at different p H were discussed.The C-phycocyaninchitosan mixture was selected to prepare emulsion,and the particle size,potential,rheological properties,microstructure,environmental stability and oxidative stability of the emulsion were characterized.The results showed that at p H 6.5,the stable mixture of C-phycocyanin and chitosan could effectively reduce the interfacial tension.The oil-in-water emulsion prepared by the mixture was a pseudoplastic fluid,which had good stability in acidic(p H 4.5-6.5)and medium temperature(50 °C)environment,and good salt ion(400 mmol/L,sodium chloride)tolerance.In addition,C-phycocyanin-chitosan emulsion had a significant inhibitory effect on lipid oxidation during storage.2.The emulsion and emulsion gel beads loaded with probiotics were prepared by mixing C-phycocyanin with pectin.The effects of active substances(curcumin,capsanthin,β-carotene and proanthocyanidins)on the number of viable probiotics in the loading system were investigated.The loading system was characterized by laser confocal,particle size distribution,rheological properties,X-ray diffraction and in vitro digestion.The results showed that the C-phycocyanin-pectin emulsion was more uniform and the particle size was smaller than that of pectin emulsion.The addition of C-phycocyanin,curcumin,capsanthin,β-carotene and proanthocyanidins could improve the apparent viscosity of the emulsion.The C-phycocyanin-pectinproanthocyanidins emulsion had the largest apparent viscosity and the smallest particle size.In addition,the gel beads prepared by the emulsion are spherical,uniform in size and different in color;during in vitro digestion and storage,the number of viable Lactobacillus plantarum in emulsion gel beads gradually decreased,but the addition of curcumin,capsanthin,β-carotene and proanthocyanidins could reduce the death of Lactobacillus plantarum,among which proanthocyanidins had the best effect.3.Probiotic-loaded hydrogels were prepared by mixing C-phycocyanin and pectin,and the effects of active substances(quercetin,resveratrol,tannin acid and gallic acid)on the number of probiotics in the loading system were explored.The results showed that increasing the concentration of C-phycocyanin could enhance the stability and hardness of C-phycocyanin-pectin hydrogel samples,and also enhance the survival rate of probiotics during gastrointestinal digestion.The addition of quercetin,resveratrol and tannin acid can improve the hardness and water holding capacity of C-phycocyanin-pectin hydrogel.Gallic acid can also improve the hardness of C-phycocyanin-pectin hydrogel,but reduce the water holding capacity of the gel.During in vitro digestion and sample storage,the number of viable Lactobacillus in the samples showed a downward trend,but tannic acid could significantly delay the decrease of viable Lactobacillus plantarum in the samples.Xray diffraction showed that tannic acid and gallic acid were completely encapsulated by C-phycocyanin-pectin gel in an amorphous state,while quercetin and resveratrol were only partially encapsulated. |
