| Curcumin has the function of preventing disease and improving human health,and it is concerned by consumers widely.However,curcumin is poor in water solubility and sensitive to food process and gastrointestinal environment,which lead to low bioavailability of curcumin.Oil bodies(OBs)are natural pre-emulsified oil droplets,and it can be used as carriers of functional nutrients.In this paper,the digestive characteristics of soybean OB emulsion under different extraction pHs and heat treatment were studied.The transport system of curcuminsoybean oil body emulsion was constructed,which provided theoretical guidance for the application of OB in food and transporting of functional nutrients.(1)The compositions and digestive characteristics of pH 5.0-SOB,pH 7.0-SOB,pH 8.0-SOB,pH 9.0-SOB and pH 11.0-SOB were explored.The contents of extrinsic protein(7S and11S)decreased from 83.9% at pH 5.0-SOB to 58.2% at pH 8.0-SOB,zeta potential increased from-21.7 m V to-14.67 m V,and particle size decreased from 924 nm to 359 nm.During stomach digestion,oleosin hydrolysis of pH 5.0-,7.0-,8.0-SOB were faster than extrinsic proteins.All 24 k Da oleosins were hydrolyzed within 5 min and 18 k Da oleosin were hydrolyzed within 30 min.Zeta potentials of all SOB emulsions decreased with the extension of digestive time,and the droplet sizes increased significantly,and aggregation were occurred.The droplets coalescence was easier in pH 9.0-and 11.0-SOB emulsions.The zeta potentials and diameters decreased gradually in intestinal phase.The FFA release rates of pH 5.0-,7.0-,8.0-SOB emulsions increased rapidly and then slowly,while FFA release rates of pH 9.0-,11.0-SOB emulsions were opposite.The total FFA releases of pH 5.0-,7.0-,8.0-,9.0-and 11.0-SOB emulsions at 180 min were 52.5%,70.5%,59%,48.8% and 43.3%,respectively.(2)The digestive characteristics of pH 7.0-and 11.0-SOB emulsion were affected by heating treatment(60℃,70℃,80℃,90℃ and 100℃).For pH 7.0-SOB,heating could cause extrinsic proteins thermal denaturation and release from the heated pH 7.0-SOB surface.The total proportion of α-helix and β-sheet decreased from 77% unheated to 36.2% at 100℃.After stomach digestion for 120 min,the hydrolysis rate of extrinsic protein in heated pH 7.0-SOB emulsion increased from 60℃～80℃,and slowed down from 90℃～100℃.Heated pH 7.0-,11.0-SOB inhibited oleosin hydrolysis.Heat treatment promoted the droplets aggregate and coalesce,which resulted in particle sizes of all emulsions increased.Differently,heated pH 7.0-SOB emulsion had larger aggregates,while the heated pH 11.0-SOB emulsion had larger oil droplets.After intestinal digestion for 180 min,particle sizes of all SOB emulsion decreased and the droplets dispersed gradually.The FFA releases of pH 11.0-SOB emulsion was greatly affected by the heating temperature,and the FFAs release was the highest at 80℃(74%).Total FFAs release was similar for all pH 7.0-SOB emulsions.In addition,the droplet charge of heated pH 7.0-SOB emulsion was lower than that of unheated emulsions in both stomach and intestine phases,while the charge change of heated pH 11.0-SOB emulsion was opposite.Different heating temperatures had little effect on particle size and microstructure in stomach phase.However,extraction pH and heating had great influence on TAGs hydrolysis.(3)The effects of pH 7.0-SOB emulsion embedding curcumin by different methods were investigated.When the oil concentration of the emulsion system was 10%,the embedding rate of pH-driven was the highest(97%),the average particle size was larger and particle size distribution was unimodal.After 7 days of storage,the stability of high pressure homogenization was poor,and more curcumin was precipitated.After gastrointestinal digestion,the release rate of free fatty acids and the bioavailability of curcumin were higher in emulsion prepared by pH-driven. |
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