Inhibition of heat-induced aggregation of a beta-lactoglobulin-stabilized emulsion by very small additions of casein.
Heat stability has been studied in model systems of oil-in-water emulsions (3 wt.% total protein, 45 vol.% n-tetradecane, pH 6.8, ionic strength 30-50 mM) with pure beta-lactoglobulin (beta-lg) as the main emulsifier. The effect of small additions of sodium caseinate, beta-casein or alpha s1-casein prior to emulsion preparation has been investigated. Samples heated for 3 min at 90 degrees C were monitored with respect to changes in viscosity and particle-size distribution. As expected, the pure beta-lg-stabilized emulsions were susceptible to heat-induced changes. But the replacement of just 1% of the beta-lg by sodium caseinate (0.03 wt.% caseinate in the total emulsion) led to complete elimination of any heat-induced viscosity or particle size increase. These findings show that a very small proportion of casein can inhibit the susceptibility of a beta-lg-based emulsion to heat-induced destabilization. The magnitude of the effect is dependent on the type of casein, with the order of effectiveness being beta-casein>sodium caseinate>alpha s1-casein. This work has potential implications for the development of milk protein-stabilized emulsions of improved shelf life.
Parkinson
Emma L
EL
Procter Department of Food Science, University of Leeds, Leeds LS2 9JT, UK.
Dickinson
Eric
E
D000818:Animals; D002364:Caseins / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007782:Lactoglobulins / Q000737:chemistry*; D046911:Macromolecular Substances; D008823:Micelles; D018613:Microscopy, Confocal; D008894:Milk Proteins / Q000737:chemistry; D010316:Particle Size; D011506:Proteins / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors; D000067816:Whey Proteins
D002364:Caseins; D007477:Ions; D007782:Lactoglobulins; D046911:Macromolecular Substances; D008823:Micelles; D008894:Milk Proteins; D011506:Proteins; D013501:Surface-Active Agents; D000067816:Whey Proteins