| In this research,a novel NC was used as a solid emulsifier or emulsifying stabilizer to stabilize emulsion and the stability mechanism was investigated.In addition,the effect of NC on food digestion during in vitro digestion and the mechanism were also proposed,which would expand the application of NC in food industry.Firstly,the characteristics of NC were investigated by TEM,particle size measurement,XRD and Zeta potential measurement,which showed low crystallinity(5.6%),small average particle size(65 nm)and no charge.NC did not find capable enough to form stable emulsion,however addition of CMC at the ratio of NC:CMC between 1:9 and 3:7 greatly inhibited creaming and coalescence of emulsion with average droplet size around 2 μm.SEM and fluorescence microscopy results demonstrated the adsorption of NC on the surface of oil droplets.The results of zeta potential and contact angle further revealed that the addition of CMC enhanced the amphiphilic character,which improved the stability of Pickering emulsion.In addition,rheology study also showed that G’ was higher than G” in emulsions stabilized by the complex of NC and CMC at the ratio of 1:9-3:7,which indicated that typical shear-thinning gel characteristics and network was formed by NC and CMC that inhibited coalescence and gravity-induced sedimentation and finally improved the stability of emulsion during storage.In second part of the study,capability of NC as an emulsifying stabilizer was investigated in combination with CMC and WPI to stabilize emulsion containing 3% oil as a model of milk drink.The results showed that emulsion stabilized with the complex of NC:CMC 9:1 had best stability,highest viscoelasticity,superior suspending stability(during 3 month storage)as compared with MCC and blank groups.By analyzing the influence of every component of system on the stability,it’s revealed that only the complex of NC and CMC at the ration of 9:1 possessed superior suspending capability and emulsifying capacity.The resultant emulsion possessed an average droplet size of 700 nm and performed highest viscosity at lower shear rate and strongest viscoelasticity along with best stability.By applying the complex of NC and CMC into peanut milk,it was demonstrated that the similar practical application effect of it as that of Aviel MCC from FMC company could be obtained when the complex of NC:CMC was used at ratio from 9:1 to 7:3.Overall,results showed that NC would have a splendid prospect of applying as an emulsifying stabilizer in drinks with particles.In the last part of the study,effect of NC on the digestion of food model containing starch,fat and protein and the mechanism were investigated via in vitro digestion model.Results showed that 0.5 wt.% NC could inhibit starch digestion significantly with an inhibition ratio around 12%,and had no influence on the digestion of fat and protein.The mechanism of NC inhibiting starch digestion was further investigated by evaluating the influence of NC on glucose adsorption,viscosity of digestion system and the activity of pancreatin.NC didn’t show any significant effect on the viscosity of digestion system and glucose adsorption,but the inhibition ratio of pancreatic α-amylase achieved 14.6%.Fluorescent spectrum revealed that the interaction of NC and pancreatic α-amylase was a kind of static quenching with around 2 bonding site.Conclusively,the adsorption between NC and pancreatic α-amylase induced changes in the microenvironment of enzyme and inhibited the enzyme activity,which further delayed and inhibited the starch digestion. |
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