Impact of Dry Heating in an Alkaline Environment on the Structure and Foaming Properties of Whey Proteins
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ORIGINAL RESEARCH
Impact of Dry Heating in an Alkaline Environment on the Structure and Foaming Properties of Whey Proteins Danilo C. Vidotto 1 & Guilherme M. Tavares 1 Received: 3 June 2020 / Accepted: 14 August 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Dry heating (DH) in an alkaline environment has been proposed as a treatment that can improve some techno-functional properties of whey proteins, such as their water-holding capacity and gelling properties. Nevertheless, information concerning the impact of DH in an alkaline environment on the foaming properties of whey proteins is not available in the literature. In this context, lyophilized whey protein isolate (WPI) powders with and without added lactose were submitted to DH treatments (60 and 80 °C) under neutral and alkaline environments for 48 h. Even without DH, the alkaline environment induced the formation of insoluble protein aggregates stabilized by disulfide and non-disulfide covalent interactions. The amount of insoluble protein aggregates enhanced with the increase in the intensity of DH. No insoluble aggregates were observed for samples produced in a neutral environment. Furthermore, no difference in the apparent secondary structure of the proteins in the soluble fraction of neutral or alkaline equivalent samples could be evidenced. In addition, the intensity of the population of soluble protein aggregates rose by increasing the intensity of DH treatment; however, it was comparable between neutral and alkaline equivalent samples. DH in an alkaline environment at 80 °C for 48 h significantly enhanced the stability of the foams produced by the soluble fraction of lactose-added samples, corroborating its potential to improve useful techno-functional properties of whey proteins. Keywords Alkaline environment . Whey proteins . Protein structure . Dry heating . Foaming properties
Introduction Whey proteins are widely used because of their great nutritional and techno-functional properties, such as their ability to act as texture modifiers, their foaming and emulsifying capacities, and their thickening/gelling properties (de Castro et al. 2017). There is a wide variety of whey protein–rich ingredients derived from bovine milk such as whey protein concentrate and whey protein isolate (WPI) (Sun-Waterhouse et al. 2014). This complex group of proteins is mainly composed of β-lactoglobulin (β-LG) and α-lactalbumin (α-LA), both of which are acidic globular proteins with 18.3 and 14.2 kDa * Guilherme M. Tavares [email protected] Danilo C. Vidotto [email protected] 1
Department of Food Science, School of Food Engineering, University of Campinas, Rua Monteiro Lobato, 80, Campinas, SP 13083-862, Brazil
molecular weight, respectively (Walstra et al. 2005). The βLG:α-LA weight ratio is approximately 3:1 in such whey protein–rich ingredients (Edwards et al. 2009). Native α-LA displays four disulfide bonds and no free thiol group, while native β-LG displays two disulfide bonds and one free thiol group, which makes it high
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