| Pterostilbene is a phenolic compound majorly found in fruits such as grapes and blueberries.It possesses several positive properties for health,including antioxidative,anticancer,and hypolipidemic activity,as well as regulating blood sugar.Nevertheless,the poor water solubility and stability of pterostilbene limited its application in the food industry It is vital to choose the proper carrier to improve its bioavailability and stability.In this study,the nanocomplexation between several food proteins and pterostilbene was studied to enhance its water solubility and thermal stability.The physical stability of nanocomplex was further improved by adding soybean polysaccharide.On this basis,the nanocomplex product was prepared by spray drying.The main methods and results of this paper were as follows:Protein-pterostilbene nanocomplexes were prepared using whey protein isolate,soybean protein isolate and flaxseed protein isolate as delivery systems.The concentrations of proteins were 20 mg/m L.The encapsulation efficiency of pterostilbene was 93.73%,87.56%,and83.32%,respectively,and the average size of particles was 229.57 nm,129.13 nm and 245.67 nm.The particle morphology was observed using atomic force microscopy,which revealed that the spherical particles were dissociated and homogenous.Through fourier transform infrared spectroscopy and fluorescence spectroscopy,it could be speculated that proteins were bonded to pterostilbene mainly by hydrophobic interaction and hydrogen bonding.X-ray diffraction showed the conversion of crystalline pterostilbene into an amorphous form.Differential scanning calorimetry results confirmed that the thermic properties of the protein were nearly unaffected after combination with pterostilbene.The nanocomplexes stabilized by flaxseed protein isolate exhibited relatively higher stability than those stabilized by soy protein isolate and whey protein isolate.The zeta potential of the flaxseed protein isolate-pterostilbene nanocomplexes maintained at about-32 m V in the temperature range of 70℃～110℃,and it also hardly changed in size distributions among all nanocomplexesIn order to further improve the physical stability of the nanocomplexes,we constructed flaxseed protein isolate-pterostilbene-soluble soybean polysaccharide nanocomplex(FPSN).It was studied that the influence of p H and soluble soybean polysaccharide concentration on the embedding effect of particles.The preparation conditions were determined when the concentration of soluble soybean polysaccharide was 10 mg/m L at p H 3.5.The average size of particles was 207.35 nm and the encapsulation efficiency of pterostilbene reached 95.06%.The result was showed that soluble soybean polysaccharide increased the particles size by atomic force microscope.Fourier transform infrared spectroscopy results confirmed flaxseed protein isolate was bonded soluble soybean polysaccharide mainly through electrostatic interaction and hydrogen bonding.Compared with flaxseed protein isolate-pterostilbene nanocomplexes,the thermal stability,p H stability,and saline ion stability of FPSN were significantly improved.Finally,the pterostilbene nanocomplex powder(FPSM)was prepared by spray drying,and the quality of the product was improved by adding maltodextrin.The optimal parameters of spray drying were obtained by single factor experiments: the inlet temperature was 150℃,the outlet temperature was 80℃ and the mass ratio of complex and maltodextrin was 1:1.It was observed by scanning electron microscope that the pterostilbene powder became much smoother with less wrinkles on their surface in the presence of maltodextrin.Additionally,maltodextrin increased the solubility and redispersibility of the powder.DPPH(1,1-diphenyl-2-picrylhydrazyl)radical scavenging rate of FPSM(89.85%)was obviously higher than pterostilbene(75.71%).Moreover,powderation improved the photo stability and storage stability of pterostilbene.After UV irradiation,the retention rate of pterostilbene in powder was over 70%,which was significantly higher than that of free pterostilbene(40.44%).In summary,the water solubility and stability of pterostilbene were improved by construction of the nanocomplex and powderation.The results were significance for the application of pterostilbene in food. |
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