Formation of heated whey protein isolate-pectin complexes at pH greater than the isoelectric point with improved emulsification properties

摘要

In this study, heated whey protein isolate and pectincomplexes (HCPX) formed at pH > isoelectric point(pI) were used to stabilize oil-in-water emulsions containing5% oil and 1.5% (wt%) protein at pH 5.5. Theeffects of pectin concentration and heating temperatureon emulsification and emulsion stabilization propertieswere determined. The HCPX were produced by heatingmixed 3% (wt) whey protein isolate and pectin (0.1or 0.3 wt%) at pH 6.2 and 75 or 85°C for 15 min.Aggregate sizes significantly increased with increasingheating temperature but decreased with the additionof pectin. The HCPX became more negatively chargedwith increasing pectin concentration; however, the effectof heating temperature was significant only at 0.1%pectin. Unheated complexes and HCPX successfullyadsorbed at the oil-in-water interface and improved theemulsification properties as shown by higher negativecharge and smaller droplet sizes. Despite the presenceof pectin, rheological properties of the emulsionswere not significantly different. All complexes showedincreased emulsion stability; however, HCPX madeat 85°C formed emulsions that were the most stableagainst creaming and heating.