Single-step concentration of whey proteins using the pressurized gas eXpanded (PGX) liquid technology: Effect on physicochemical properties and scale-up

Abstract

Pressurized Gas eXpanded (PGX) Liquid Technology precipitates and dries biopolymers using CO2-expanded organic solvents, producing open-porous materials with micro- and nanostructures. This study investigated the concentration of whey proteins from sweet whey liquid using PGX Technology as a single-step process at different scales and mass flow rate ratios (θPGX) of PGX fluid (CO2+Ethanol) to sweet whey liquid. The PGX process efficiently removed >50% dwb lactose and lipids from the feedstock, forming a whey protein concentrate (PGX-W, ≥45% protein dwb) consisting mainly of β-lactoglobulin, α-lactalbumin, and bovine serum albumin. At low θPGX, PGX-W had high protein concentrations (50% dwb), with reduced solvent effects on protein secondary structure. At high θPGX, PGX-W contained 14% dwb lactose, higher than the <5% dwb obtained at lower flow rates and had finer morphologies (tens of nm) with increased specific surface area (13–29 m2/g). Resulting PGX-W powders were free-flowing with low bulk density (35–74 g/L) and high-water solubility (≥80%).