Influence of oral movement, particle size, and zeta potential on astringency of whey protein

Abstract

Astringency is an important characteristic in whey protein products that leads to lower consumer liking, improvements in astringency may improve consumer acceptance of high protein products. The contributions of oral movement, particle size, and zeta potential on the perception of whey protein astringency were investigated. Trained panelists documented the astringency of 10% (w/w) whey protein isolate (WPI, >90% protein) solutions at pH 3.4 or 7.0 with or without oral movements. In a second experiment, 67 commercial WPI and whey protein concentrate 80% protein (WPC80) were evaluated for particle size and zeta potential at neutral pH, and of these, 21 were selected for further evaluation of astringency. Acidification of WPI increased astringency, but astringency was also documented in a neutral pH range (pH 6.0–7.0). Oral movements increased the perception of astringency (p < 0.05), suggesting that part of the astringent sensation was due to the interaction of whey proteins with receptors on oral tissues and oral movement further increasing astringency perception, possibly by friction of delubricated oral surfaces. Commercial WPI and WPC80 varied widely in particle size, zeta potential, and astringency. Astringency of WPI solutions were correlated with zeta potential (p < 0.05, r = −.81). WPC80 were astringent, but astringency of WPC 80 was not correlated with particle size or zeta potential (p > 0.05, r = .14, .40). These results provide information on the mechanism of whey protein astringency perception, which may facilitate the development of whey protein products with decreased astringency. Practical Applications Astringency of whey proteins is complex and a result of multiple mechanisms. This study established that oral movements and zeta potential are linked to the astringency of whey protein. These results further explain the mechanisms of astringency and may help to identify possible methodologies to reduce astringency in whey protein ingredient applications.

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