The Digestion Fate Of Citrus Pectin Stabilized Citrus Oil-based Emulsions

Precision nutrition has become a new direction in the field of food nutrition,which could be achieved by designing a high encapsulation and targeted release delivery emulsion system.Triacylglycerol–bergamot oil emulsions have a smaller size and showed better stability compared with pure triacylglycerol oil emulsions,but the emulsion stability and digestion fate were still unknown.Besides,compared with other polysaccharide emulsifiers-stabilized emulsions,citrus pectin stabilized citrus oil emulsion showed better stability.The digestion fate of the emulsion stabilized by different concentrations of citrus pectin,and the changes in its interfacial properties during digestion were totally unknown.In this study,triacylglycerol oil was used in combination with bergamot oil at different mixing ratios as the oil phase to produce nobiletin–encapsulating emulsions.The emulsion stability,digestion fate,and bioavailability of nobiletin were systematically investigated.After selecting the ratio of the mixed oil phase,the upper digestion fate of an emulsion stabilized by different concentrations of citrus pectin and the changes in its interfacial properties during digestion were investigated.The main results are as follows:(1)Stability and digestion fate of triacylglycerol–bergamot oil emulsions: Long-chain triglycerides(LCT,i.e.,corn oil)and medium-chain triglycerides(MCT)were used in combination with bergamot oil as the oil phase to produce nobiletin–encapsulating emulsions.The triacylglycerol–bergamot oil emulsion at the 1: 3 ratio was the most stable.The hydrolysis rate of triacylglycerol–bergamot oil emulsions increased with increasing triacylglycerol: bergamot oil ratio.The total bioavailability of nobiletin in corn oil–bergamot oil emulsions was higher than that of pure bergamot oil and MCT–bergamot oil emulsions during in vitro digestion.That was due to the higher hydrolysis rate of corn oil–bergamot oil and greater solubilization capacity of micelles formed by bile salts and long-chain fatty acids(LCFAs)from corn oil.Nobiletin bioavailability was highest in the corn oil: bergamot oil emulsion(3: 1).This study mainly reveals the reasons for the improvement of emulsion stability and the bioavailability of nobiletin.(2)Interface behavior of citrus pectin stabilized emulsion during upper digestion: Stable emulsions were created using concentrations of citrus pectin ranging from 0.5 % to 3.5 %;whey protein(1 % and3 %)and modified starch(1 % and 3 %)were used as controls.The digestion fate of these emulsions and the interfacial behavior of emulsifiers were investigated.The interface layer of the emulsion stabilized by modified starch and whey protein were digested in the mouth and stomach respectively,then these two emulsions were easily digested in the small intestine.In contrast,the emulsions stabilized by citrus pectin were relatively stable in the mouth and gastric stages,but their stability in the intestinal stage was dependent on the pectin concentration.The interface layer formed by a citrus pectin concentration of less than 3 % was almost replaced by bile salts,which then facilitated the adsorption of lipase and promoted the hydrolysis of oil droplets by lipase.However,high concentration of citrus pectin(? 3 %)formed a uniform and thick adsorbed layer,which was not affected by enzymes in the mouth and stomach.In the small intestine,the interface combined with,instead of being replaced by,the bile salts.Thus,the bile salts combined with 3 % citrus pectin were adsorbed on the O/W interface and produced a stronger barrier against displacement of the rest of the bile salts,thereby inhibiting the adsorption and digestion of lipase.These results will be useful for designing emulsion-based functional foods that can achieve large intestine targeted release.This study clarified the digestion fate of citrus pectin stabilized triacylglycerol–bergamot oil emulsions,and provided theoretical guidance for the design for precision nutrition and targeting delivery.The results were also useful for designing emulsion-based delivery systems in functional foods and beverages.