Whey protein as a key component in food systems: Physicochemical properties, production technologies and applications

Abstract

Whey protein is a potential and versatile ingredient in the development of novel and natural component in food products. It can work as a texture modifier, thickening agent, carrier/vehicle, gelling agent, surface-active component, and foaming agent among other associated functionalities and bioactivities. Nanocomposites containing whey proteins, for example, have been used as effective encapsulation systems of active food and drug components, enhancing their solubility, transport, dispersibility, bioavailability and bioaccessibility. This review provides an overview of the functional and biological properties of whey protein as a key component in food systems, focusing on their physicochemical/structural characteristics, production technologies and applications.

Introduction

Milk proteins consist of two major fractions: casein and whey. Whey is the liquid produced as a by-product of the dairy industry during cheese making or other coagulated dairy product processing and is comprised of approximately 85–90% water with a solid fraction composed of lactose, proteins, lipids and minerals in which the whey proteins account for approximately 20% of the total milk protein (Brandelli, Daroit, & Corrêa, 2015; Pihlanto-Leppälä, 2000, Yadav et al., 2015). Due to its very large production amount, proteins isolated from whey are becoming an increasingly popular functional and active food ingredient. Whey protein is rich in essential amino acids, such as leucine, valine, isoleucine and cysteine, which are important agents in metabolism, neural function and homeostasis (Patel, 2015). The main proteins in whey are β-lactoglobulin (β-LG), glycomacropeptide (GMP), α-lactalbumin (α-LA), immunoglobulins (Igs), bovine serum albumin (BSA), lactoferrin (LF), lactoperoxidase (LP) and proteose peptone (PP) (Yadav et al., 2015).

Whey proteins can be transformed into value-added products and used in various food products due to their GRAS (General Recognized as Safe) status. Using physical processes, such as evaporation, spray-drying, and freeze drying, it is possible to convert this by-product into whey powder, concentrated whey protein, isolated whey protein, whey permeate, and lactose among other products. Using biotechnological processes (fermentation and enzymatic hydrolysis), the raw whey can be used for biotransformation feed, bio-proteins (single cell protein – SCP), prebiotics and bioactive peptides (Udenigwe and Aluko, 2012, Yadav et al., 2015).

Particular physico-chemical characteristics of whey protein have made this product an excellent ingredient for incorporation in food products. Several studies have demonstrated that whey protein can be used as an emulsifying, thickening, gelation, foaming, and water-binding agent resulting in manufactured products with similar and desired characteristics compared to those produced with classical ingredients. It is worth noting that studies of different proteins modification technologies can be seen as important tools in the development of new products, such as edible films, coatings, hydrogels and nanoparticles. The application feasibility of whey proteins as a food component has been strengthened especially based on the rheological and structural characteristics of the products obtained using them (Cinelli et al., 2014; Moakes, Sullo, & Norton, 2015; Nicolai, Britten, & Schmitt, 2011; Tarhan, Spotti, Schaffter, Corvalan, & Campanella, 2016).

In addition, whey proteins are important sources of bioactive peptides that can be defined as specific sequences of amino acids that promote a positive impact in human body systems. These peptides can present antioxidant, anti-hypertensive and antimicrobial activities among other effects. Using whey proteins as the substrate, bioactive peptides can be obtained by fermentation or enzymatic hydrolysis in which other technologies may also be applied in association to improve the bioactivities (de Castro & Sato, 2015).

As a result of intense and relevant studies, the objective of this work is to provide a review of the main properties of whey proteins associated with a special discussion of the strategies applied in the most recent studies for the use of whey protein as a functional, technological and bioactive ingredient.