Study On The Preparation And Properties Of Resveratrol-dietary Fiber Composites

Resveratrol(Res)is a natural polyphenol with various biological activities such as cardioprotection effect,anti-inflammatory activity,antioxidant effect,and anti-carcinogenic activity.Res can be used as a functional additive in the food industry,however,Res has poor water solubility which limits its incorporation into food products.Biopolymer particles could effectively improve the water solubility,bioaccessibility,and stability of Res,enabling Res to fully exerted its effect in food.Cereal dietary fiber(DF)played an important role in whole grain food health and could be covalently or noncovalently bound to polyphenol to produce a synergistic effect.So,cereal DF was selected as the carrier matrix to produce biopolymer particles to deliver Res.Three commonly available and stable cereal dietary fiber,corn soluble dietary fiber(CSDF),resistant starch(RS),and resistant maltodextrin(RM),were chosen as carrier matrices,and Res-CSDF composite,Res-RS composite,and Res-RM composite were prepared by antisolvent precipitation.Res-RS composite was chosen as an example,loading ability and loading efficiency were selected as evaluation indexes,and single factor experiments were carried out to determine the optimum conditions.The high loading ability(8.92%)and loading efficiency(88.63%)of Res-RS composite could be achieved when the optimum conditions were employed:10%Res content,6?1 volume ratio of antisolvent(water)to solvent(ethanol)and 20 h standing time.Under the same conditions,the loading ability and loading efficiency of Res-CSDF composite were 8.29%and 83.11%,and the loading ability and loading efficiency of Res-RM composite were 8.05%and 80.49%,respectively.Scanning electron microscope,fourier infrared spectrometer,X-ray diffractometer,and thermogravimetric analyzer were employed to characterize Res-DF composites.The results showed that the shape of Res became irregular,the size of Res became smaller and the thermal stability of Res decreased slightly after forming composites with DF.Additionally,the interaction between Res and DF was mainly hydrogen bonding and Res existed in composites in an amorphous form.The water solubility and bioaccessibility of Res-DF composites were measured.It was found that the water solubility and bioaccessibility of Res were significantly improved after Res formed composites with DF.The reduced particle size and amorphous form of Res in composites were probably responsible for the improved water solubility and bioaccessibility of Res.The new hydrogen bonding formed between Res and DF also increased water solubility and bioaccessibility of Res in the composites.Compared to raw Res,the DPPH and ABTS~+free radical scavenging activities of Res-DF composites increased by 65%and 63%,respectively,which implied that Res-DF composites had higher antioxidant activity than raw Res and may be more suitable as dietary supplements or food ingredients.In the in vitro release test of Res-DF composites,the release profile of Res from all composites showed a biphasic behavior and the cumulative release of Res in all composites reached 70%at 12 h.Furthermore,DF matrices could increase the dissolution rate of Res.The release kinetics of Res were investigated by fitting the release data into release models to study the release mechanism of Res from Res-DF composites.The release data of Res-DF composites more appropriately fitted with Weibull model.The fitting results showed that the release of Res from CSDF and RS followed Fickian diffusion and the release mechanism of Res from RM was a combined mechanism(Fickian diffusion and Case II transport).Res-DF composites were stored at room temperature for 12months,and the crystallization properties of Res had few changes,indicating that Res-DF composites had good storage stability.In the process of gelatinization and retrogradation of starch,the breaking and formation of hydrogen bonding play a key role.It was found that new hydrogen bonding formed between Res and RS during the preparation of Res-RS composite,making the increase of water solubility of RS and the decrease of crystallinity of RS.Based on this phenomenon,Res-RS composite was applied to wheat starch systems to study its effects on gelatinization and regeneration of wheat starch.The results showed that after adding the Res-RS composite,the peak viscosity,trough and final viscosity of wheat starch significantly increased,and the pasting temperature decreased.Moreover,Res-RS composite could inhibit retrogradation of wheat starch,which provided a new idea for solving the problem of wheat starch retrogradation in industrial production.