Astringency of Bovine Milk Whey Protein

Abstract

Whey protein solutions at pH 3.5 elicited an astringent taste sensation. The astringency of whey protein isolate (WPI), the process whey protein (PWP) that was prepared by heating WPI at pH 7.0, and the process whey protein prepared at pH 3.5 (aPWP) were adjusted to pH 3.5 and evaluated by 2 sensory analyses (the threshold method and the scalar scoring method) and an instrumental analysis (taste sensor method). The taste-stimulating effects of bovine and porcine gelatin were also evaluated. The threshold value of astringency of WPI, PWP, and aPWP was 1.5, 1.0, and 0.7 mg/mL, respectively, whereas the gelatins did not give definite astringency. It was confirmed by the scalar scoring method that the astringency of these proteins increased with the increase in protein concentration, and these proteins elicited strong astringency at 10 mg/mL under acidic conditions. On the other hand, the astringency was not elicited at pH 3.5 by 2 types of gelatin. A taste sensor gave specific values for whey proteins at pH 3.5, which corresponded well to those obtained by the sensory analysis. Elicitation of astringency induced by whey protein under acidic conditions would be caused by aggregation and precipitation of protein molecules in the mouth.

The effect of consumption volume on profile and liking of oral nutritional supplements of varied sweetness: Sequential profiling and boredom tests

“…It is hypothesised that another source of mouthdrying could be the milk proteins typically used in ONS formulations. Previous studies have shown whey proteins to cause mouthdrying through precipitation onto the tongue (Sano, Egashira, Kinekawa, & Kitabatake, 2005); alternatively proteolysis of on b-casein can yield c-caseins which are associated with perceived dryness of milks (Harwalkar, Cholette, McKellar, & Emmons, 1993).…”

“…Components other than iron sulfate, intrinsic to ONS, such as the calcium and milk proteins, may contribute to these attributes. In support of this, calcium salts have been shown to exhibit both astringent and metallic taste properties (Lawless, Rapacki, Horne, & Hayes, 2003) and both whey protein precipitation and casein proteolysis products have been associated with mouthdrying (Harwalkar et al, 1993;Sano et al, 2005). Further research into the properties of ONS ingredients may help to elucidate potential causes of the build up of attributes over repeat consumption.…”

The astringency of whey protein beverages is caused by their acidity

“…Though whey proteins are soluble over a wide pH range, whey protein beverages are often formulated at low pH for improved beverage clarity and heat stability (Miller, 2007). Acidic whey protein beverages, however, have been shown to be astringent (Beecher, 2006;Sano, Egashira, Kinekawa, & Kitabatake, 2005), which may limit consumer acceptance of these products.…”

The effect of dynamic heat treatments of native whey protein concentrate on its dispersion characteristics

“…Where caseins may be directed to cheese production, whey proteins possess an important role as structure enhancers in fresh fermented dairy products, such as yoghurt (Johnson & Lucey, 2006). Increasing the proportion of whey proteins in dairy products is, however, not without challenges, as consequences such as increased astringency (Sano, Egashira, Kinekawa, & Kitabatake, 2005;Tomaschunas, Hinrichs, K€ ohn, & Busch-Stockfisch, 2012), altered aggregation behaviour upon heating and acidification (Kücükcetin, 2008), and decreased aroma intensity (Tomaschunas et al, 2012) may occur.…”