| Abstract
| - The emulsifying ability, heat stability, and coalescence stability of oil-in-water emulsions preparedwith whey protein of varied degrees of hydrolysis (DH), and at varied protein contents, was studied.Whey protein hydrolysates (WPH) with a DH of 4% and 10% had poorer emulsifying ability thannon-hydrolyzed whey protein concentrate (WPC), but were more heat stable. Increasing DH between10 and 27% improved emulsifying ability and further improved the heat stability of the emulsiondroplets. Increasing DH from 27 to 35% led to a big decrease in both emulsifying ability and heatstability. The quiescent coalescence stability of WPH emulsions was relatively good up to a DH of27%. Above DH 27% emulsions become highly unstable. It appears that two mechanisms of instabilityare at work here. At low DH heat-induced denaturation and aggregation occur. In the DH range of4−20% heat stability increases as protein globular structure is disrupted. At a DH greater than27% we see a change from a hydrolysis-induced increase in heat-stability to coalescence instability,with a resultant large increase in emulsion breakdown during heating. Keywords: Emulsion; heat stability; hydrolysates; coalescence
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