Factors Determining Yield Stress and Overrun of Whey Protein Foams

Abstract

Foams were formed by whipping whey protein solutions (15% w/v protein) containing NaCl, CaCl 2 , lactose, or glycine. Foam overrun and yield stress were determined. Foams made from whey protein ingredients have greater overrun and yield stress if the concentration of b-lactoglobulin is high relative to a-lactalbumin. The presence of 0.4 M CaCl 2 in the foaming solution increases overrun and yield stress for b-lactoglobulin and a-lactalbumin. The high yield stress of b-lactoglobulin and a-lactalbumin foams made from solutions containing CaCl 2 suggests that CaCl 2 is altering rheological properties of the interfacial protein film and/or contributing to protein aggregation or network formation in the lamellae.

Foaming and interfacial properties of hydrolyzed β-lactoglobulin

“…Note these solutions were all at a protein concentration of 5% w/v. Data for whey protein isolate solutions at protein concentrations of 5 and 10% w/v protein were included for comparison with previous work [4][5][6][7][8]. Heating at 90 • C/15 min reduced τ 0 for all hydrolysates, but this effect was minimal for the trypsin hydrolysate.…”

“…Several commercial whey protein hydrolysates were found to improve foam τ 0 as compared to whey protein isolate (WPI) on an equal protein basis, although the mechanism for this improvement was unclear [6]. A potential correlation between interfacial dilatational elasticity (E ) and τ 0 has been noted for whey proteins solubilized across a range of electrostatic conditions [7] and varying degrees of polymerization [8]; however, this relationship was untested for hydrolyzed whey proteins.…”

“…Common means of evaluating foam surfactants include their capacities to efficiently form foams (foamability), stabilize foams, and impart specific foam rheological properties [2,3]. Foam rheological studies have received far less attention than those pertaining to foamability and/or foam stability, although understanding the mechanisms responsible for protein-based foam yield stress (τ 0 ) has been a recent focus for our research group [4][5][6][7][8].…”

Influence of the Addition of Ovalbumin and Emulsifier on the Physical Properties and Stability of Yacon (Smallanthus sonchifolius) Juice Foams Prepared for Foam Mat Drying Process

“…The yield stress test was carried out in duplicate by rotational rheometry with vane-type rotors and rereadings at 10 and 20 min (Pernell et al 2000;Luck et al 2002;Yang et al 2009). Shortly after whipping, each foam was carefully added to glass beakers (±50 ml) which were placed in a Brookfield rheometer (R/S plus, Brookfield Engineering Laboratories Inc., Middleboro, MA, USA).…”

The Role of Copper in Protein Foams

“…Overrun measurements were made using the method of Luck et al 9 Foam was scooped into a 106-ml weigh boat 10-12 times and weighed. The mean of these measurements was used to calculate overrun: % overrun ¼ wt: 106 ml dispersion ð Þ À wt: 106 ml foam ð Þ wt: 106 ml foam ð Þ…”