Effect of pH and heat treatment of cheese whey on solubility and emulsifying properties of whey protein concentrate produced by ultrafiltration

Physicochemical properties of liquid virgin whey protein isolate

“…DSC analyses showed that there was about 18% decrease in the enthalpy of denaturation of LVWPI (results not shown) after heat treatment. This is in agreement with the finding of Fachin and Viotto (2005) who reported reduction of WP solubility at pH 6 in fresh UF retentates from sweet whey after being subjected to heat treatment of 68 1C for 2 min, an indication of fractional denaturation. The heat-treated WPC-80 solution in the present study turned to gel upon cooling following heat treatment; therefore, its viscosity was not shown in Fig.…”

“…Heat treatment: WP solutions (20 mL) at pH 6.070.1 with the same protein concentration as the fresh LVWPI were heated at 65 1C for 2 min to induce structural unfolding of the proteins without massive aggregation (Dybing & Smith, 1991;Fachin & Viotto, 2005). The heating rate from room temperature to 65 1C was about 5 1C min À1 .…”

“…The loss of native conformation during cheesemaking and subsequent processing alter their functionality and reduce their biological activity (Bounous & Gold, 1991;de la Fuente, Hemar, Tamehana, Munro, & Singh, 2002;de Wit, 1998;Kilara & Mangino, 1991;Patel, Kilara, Huffman, Hewitt, & Houlihan, 1990;Vardhanabhuti & Foegeding, 1999). Thus, practicing the appropriate conditions to achieve desired functionality in the commercial WP products remains a challenge to date (Etzel, 2004;Fachin & Viotto, 2005;Onwulata, Konstance, & Tomasula, 2004). Although proteins could assume many three-dimensional shapes, only the ''native conformation'' may be biologically significant (Dybing & Smith, 1991).…”

Whey protein-stabilized emulsion properties in relation to thermal modification of the continuous phase

“…2). The heat treatment applied to whey before the ultrafiltration step of WPC manufacture causes that even non-heated dispersions are poor in native proteins (Fachin and Viotto, 2005;Marcelo and Rizvi, 2008). Thus, the native proteins would scattered much more light.…”

Skim acidic milk whey cryoconcentration and assessment of its functional properties: Impact of processing conditions

“…In our study, the emulsifying properties (emulsion stability and activity indexes) of the cryoconcentrated whey studied at pH 4.35 correspond to the isoelectic point of the major protein fraction in the whey. The EAI is related to the ability of the protein to be adsorbed at the surface of fat globules and its capacity to unfold/spread over the interface, stabilizing the new area created (Fachin, & Viotto, 2005;Pearce & Kinsella, 1978). The emulsion activity index depends on the conformational changes of the proteins.…”