| Quercetin(QUE)was a lipophilic polyphenol widely found in fruits and vegetables that exhibits excellent physiological functions,such as,antioxidant,anti-inflammatory,anti-aging and anti-cancer physiological functions.However,the application of QUE as a nutritional supplement in the food industry was limited due to its poor water solubility,chemical stability and low oral absorption rate.Sodium caseinate(NaCas)can form stable complexes with hydrophobic small molecules,exhibiting good performance in enhancing water solubility and stability.Furthermore,previous studies have shown that dietary lipids can enhance the absorption of lipophilic substances compared to protein-based encapsulation methods.Therefore,In this study,ultrasound technology was utilized to support the self-assembly of FAs and NaCas into complexes,which were then employed as delivery carriers for QUE to investigate their enhancement effects on QUE encapsulation,thermal stability,storage stability,and bioavailability.The results are as follows:Ultrasound-mediated preparation of oleic acid(OA)-NaCas self-assembled vector and its encapsulation effect on QUE.The optimum conditions for preparation of OA-NaCas complex were as follows: NaCas concentration 4.00 mg/mL,ultrasonic power 300 W and ultrasonic time5 min.Under these conditions,the differences in encapsulation efficiency of QUE with different OA:NaCas mass ratios(1∶40/1∶15/1∶8/1∶4)were compared.The results showed that when the mass ratio of OA:NaCas is 1∶15 or 1∶8,the embedding rate of QUE was above 95.00%,and regular spherical particles were formed.When OA-NaCas-QUE composites were heated at 80℃for 100 min,QUE retention rates were all above 80.00%.In vitro simulation digestion experiments showed that the bioaccessibility of QUE was significantly improved after loading with OA-Nac As complex.When the mass ratio of OA:NaCas was 1:8,the bioaccessibility of QUE reached 67.30%,2.60 times higher than that of free QUE.This study investigated the preparation of different FAs-NaCas-QUE complexes and the interaction between QUE and FAs-NaCas.The research examined three saturated fatty acids,lauric acid(LA),palmitic acid(PA),and stearic acid(SA),as well as three unsaturated fatty acids,oleic acid(OA),arachidonic acid(AA),and docosahexaenoic acid(DHA),to obtain a uniform and stable FAs-NaCas system.The optimal ratios were 1∶40 for LA/PA/SA-NaCas and1∶15 for OA/AA/DHA-NaCas.Multispectral analysis showed that QUE was mainly bonded with NaCas or FAs-NaCas by hydrogen bonding,and quench protein fluorescence in a static manner.The introduction of FAs done not change the binding way of QUE and NaCas,but increaseed the binding constant K value of Nacas-Que and improved the stability of Nacas-Que.Molecular docking showed that QUE was bound to Leu123 and Glu60 of NaCas.LA/PA/AA did not change the binding site between QUE and NaCas,while SA/OA/DHA led to the change of the binding site between QUE and NaCas,and QUE was bound with Glu79,Glu86 and Lys90.Effect of different FA-NaCas complexes on QUE stability.QUE was embedded with the complex of NaCas,LA-NaCas,PA-NaCas,SA-NaCas,OA-NaCas,AA-NaCas and DHA-NaCas as carriers,and stored at 4℃ for 28 days in the dark.QUE retention rates were increased by 1.70,3.71,3.01,2.96,2.89,2.36,2.35 times,respectively.When heated at 100℃ for 20 min,QUE retention rate increased by 1.78,2.31,2.12,2.08,1.82,1.82,1.72 times,respectively.After simulated gastrointestinal digestion in vitro,the bioaccessibility of QUE was increased by30.10%,44.23%,40.51%,43.92%,39.30%,44.32% and 46.64%,respectively.Among them,LA-NaCas complex have the most obvious effect on improving the storage stability and thermal processing stability of QUE,while DHA-NaCas was more conducive to improving the biological accessibility of QUE. |
