Recovery of Protein from Dairy Milk Waste Product Using Alcohol-Salt Liquid Biphasic Flotation

Abstract

Expired dairy products are often disposed of due to the potential health hazard they pose to living organisms. Lack of methods to recover valuable components from them are also a reason for manufactures to dispose of the expired dairy products. Milk encompasses several different components with their own functional properties that can be applied in production of food and non-food technical products. This study aims to investigate the novel approach of using liquid biphasic flotation (LBF) method for protein extraction from expired milk products and obtaining the optimal operating conditions for protein extraction. The optimized conditions were found at 80% concentration ethanol as top phase, 150 g/L dipotassium hydrogen phosphate along with 10% (w/v) milk as bottom phase, and a flotation time of 7.5 min. The protein recovery yield and separation efficiency after optimization were 94.97% and 86.289%, respectively. The experiment has been scaled up by 40 times to ensure it can be commercialized, and the protein recovery yield and separation efficiency were found to be 78.92% and 85.62%, respectively. This novel approach gives a chance for expired milk products to be changed from waste to raw materials which is beneficial for the environment and the economy. Processes 2019, 7, 875 2 of 18Of the proteins in milk, 80% is Casein and the remaining 20% is Whey protein [3]. Casein is chiefly phosphate-conjugated and mainly consists of calcium phosphate-micelle complex. Whey protein is a collection of a globular proteins with a high level of α-helix structure and the acidic-basic and hydrophobic-hydrophilic amino acids are distributed in a fairly balanced form. Whey proteins have substantial levels of secondary, tertiary, and quaternary structure. They are heat-labile stabilizing their protein structure through intermolecular disulfide linkage [4]. The proteins in milk are considered to be complete as they contain all types of essential amino acids in amounts that match the amino acid requirements. They are used as a standard reference for proteins to compare with other food proteins due to their high quality. Branched-chain amino acids contents such as valine, isoleucine, and leucine in milk are also higher than many other foods [4].Since the conventional technique for extracting bioactive compounds need longer extraction time yet cost-consuming with complex scale-up, the liquid biphasic flotation (LBF) method was proposed [5]. LBF system is an integration of the adsorptive bubbles floatation system, where the biphasic system is supported with air bubbling to transport the biomolecules from one phase to another. The surface-active compound of biomolecules present will be absorbed onto the surface of ascending gas bubble and be brought from the bottom phase to the top organic phase [6]. LBF is formed by combining an immiscible polymer and a salt solution. Addition of salt to water will cause segregation of ions into their preferred water structuring [7]. Aqueous biphasic systems will occur when certain solutes cause an aqu...

Liquid Biphasic System: A Recent Bioseparation Technology

“…Examples of these sources are microalgae, fruit, lignocellulose biomass, secondary product, and crop waste. Separation and purification techniques for the recovery of biomolecules (e.g., proteins, carotenoids, and lipids) requires a precise operating condition to ensure high value end-products can be obtained [1,2]. Established extraction techniques such as membrane separation, chromatography-based method, ultrafiltration, and precipitation usually involve multiple step operations, complex pathways, time consuming operations, high energy inputs, and high cost for the recovery and extraction processes [3][4][5].…”

“…Furthermore, various assisted technologies such as bubbling, ultrasound, and electrolysis have been incorporated into the LBS to enhance the effectiveness of biomolecules separation [9][10][11][12]. The application of the LBS has been applied for the extraction, separation, and purification of proteins, lipids, and carotenoids from microalgae [2,13].…”

Protein recovery as a resource from waste specifically via membrane technology—from waste to wonder

“…The recovery of collagen protein powder separated from chromium leather scrap waste was studied, revealed to be containing different amino acids and displaying a low concentration of mineral salt that can be used as fertilizer (Dang et al 2019 ). A huge amount of waste is produced by the dairy industry, such as whey, the main by-product that is produced during the production of cheese from milk, which is also an abundant source of valuable proteins (Gopinatha Kurup et al 2019 ; Tham et al 2019 ). The combination process of ultrafiltration and nanofiltration membranes has been used to obtain up to 90% of proteins from whey waste along with lactose under defined parameters (Das et al 2016 ).…”

Enhanced Growth Performance Of Microalgal Biomass For Lipid Production

“…Chlorella vulgaris has shown enhanced growth in a neutral, pH 7 level while Desmodesmus denticulatus preferred the unadjusted pH of control media. According to Tham et al, (2019), Chlorella vulgaris can adapt in a wide range of pH, from 4 to 10 with the highest biomass productivity obtained at pH 9 to 10.…”