Application of Bentonite Adsorption for the Removal and Fractionation of Protein from Acid Whey

Abstract

The recovery of valuable components from dairy waste presents an opportunity to generate economic value for producers while reducing the environmental burden associated with treatment and disposal. Gaps in cheese whey utilization persist due to the lack of accessible treatment options for small-scale producers to valorize their waste, necessitating investigation into alternative technologies. To address this, bentonite clay was evaluated as an adsorbent for recovering and fractionating proteins from acid whey. The objectives of this investigation were to optimize the adsorption process, gain insights into the mechanisms responsible for adsorption and identify suitable applications of the process. The process was evaluated through a series of batch adsorption experiments, in which key operational parameters, including contact time, adsorbent dosage, pH, and temperature, were systematically varied. Adsorption performance was quantified, with a focus on the removal and separation of the major whey proteins, alpha-lactalbumin (α-LA) and beta-lactoglobulin (β-LG). Adsorption of major whey proteins using bentonite reached equilibrium after 10 hours at 20 g/L and pH 4.7, with α-LA exhibiting a higher rate constant under pseudo-second-order kinetics. Increasing bentonite dosage to 30 g/L enabled complete protein removal at equilibrium. Elevated temperatures enhanced removal efficiency, while pH variation from 3 to 9 revealed the potential for selective adsorption, with α-LA removal favoured at low pH, and β-LG at high pH. The selective removal of the major whey proteins was optimized using factorial experiments. Variation of pH and temperature was used to determine an optimal region for the selective removal of β-LG. Further optimization of the adsorbent dosage and contact time resulted in a condition where β-LG removal reached 88%, while α-LA removal was only 26%. This investigation establishes this process as an effective means of whey processing, utilizing a low-cost, scalable strategy. Bulk removal of whey proteins via adsorption is a viable technique for producers unable to implement conventional membrane filtration systems, providing a valuable unit operation for separating protein from whey. Furthermore, the method’s potential to fractionate major whey proteins enables the generation of high-value, pure protein fractions, thereby presenting an opportunity to reduce the cost and complexity of traditional processing approaches.Dairy Farmers of OntarioOntario Ministry of Farming, Agriculture and Agribusiness and Ministry of Rural AffairsNational Research Council Canad