Food Hydrocolloids 112 (2021) 106303 Available online 4 September 2020 0268-005X/© 2020 Elsevier Ltd. All rights reserved. Review Biomolecule-based pickering food emulsions: Intrinsic components of food matrix, recent trends and prospects Anuj Niroula a , Tanesh D. Gamot b, c , Chien Wei Ooi d, e , Sushil Dhital f, * a Department of Food Technology, Nagarik College, Tribhuvan University, Gaindakot, Nepal b Nanoscale Science and Engineering Laboratory (NSEL), Department of Mechanical and Aerospace Engineering, Monash University, Clayton Campus, VIC, 3800, Australia c ARC Research Hub for Graphene Enabled Industry Transformation, Monash University, Clayton Campus, VIC, 3800, Australia d Chemical Engineering Discipline, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunwav, 47500, Selangor, Malaysia e Monash-Industry Palm Oil Education and Research Platform, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, 47500, Selangor, Malaysia f Department of Chemical Engineering, Monash University, Clayton Campus, VIC, 3800, Australia A R T I C L E INFO Keywords: Biomolecules Pickering emulsion Particle prerequisites Components in food matrix Bioactive molecules ABSTRACT Dietary fat in food matrix plays an important role in improving the bioaccessibility of lipophilic micronutrients. Conventionally, surfactants and amphiphilic biopolymers have been used to stabilize the lipid and aqueous phase. Recently, the particle-stabilized emulsions, or referred to as ‘Pickering emulsions’, are studied extensively due to their better stability and potential applications in addition to the benefts of conventional emulsions. Inorganic particles are often criticized for causing irritation, damage to tissues and environment-related issues; hence biopolymers have emerged as promising Pickering particles. Hydrocolloids especially polysaccharides and proteins have been widely studied for their potential as a biopolymer-based Pickering particle and used in food- grade applications. However, particle properties like wettability, surface charge, size, and shape determine their applicability as Pickering particle. Majority of previous studies involved the model aqueous systems (water or buffer) as a continuous aqueous phase. In this review, the roles of intrinsic food-components like salts, pH, surfactants and colloids of food matrix and their potential in developing food-grade Pickering emulsions are discussed. Different strategies for the inclusion of lipophilic bioactive molecules in food-grade Pickering emul- sions were systematically reviewed. Also, investigations on other aspects of developing food-grade Pickering emulsions, including sustainability of processing, particle modifcation strategies, and development of innovative Pickering food products, are on the rise. Further investigations in these areas could elaborate the scope of Pickering stabilization of food matrix and extend food-grade applications of biomolecule-based Pickering emulsion in nutraceuticals, pharmaceuticals and cosmeceuticals. 1. Introduction Consumers’ demand for healthier and more natural foods has been increasing rapidly. The incorporation of low dietary fat in food matrices has been suggested as means to increase the nutritional quality and to improve the bioaccessibility of lipophilic micronutrients (Silva et al., 2014). The colloidal systems with fats acting as a dispersed phase in the continuous aqueous phase of food matrices are referred to as oil-in- water (O/W) emulsions (Leal-Calderon, Bibette, & Schmitt, 2007; McClements, 2017; Tadros, 2013). Thermodynamically, emulsion is an unstable system that undergoes physicochemical mechanisms like coa- lescence, creaming, and Ostwald ripening, leading to its separation into the initial phases (Berton-Carabin & Schro¨ en, 2015; McClements, 2017; Ortiz, Pochat-Bohatier, Cambedouzou, Bechelany, & Miele, 2020). Emulsifers or surfactants are generally used to stabilize the emulsions for a duration ranging from a few weeks to months (Leal-Calderon et al., 2007; McClements, 2017; Tadros, 2013). The presence of an emulsifer or a surfactant during emulsifcation minimizes the interfacial energy between the immiscible phases by various mechanisms like adsorption, encapsulation, or chemical linkages (Rekvig, Kranenburg, Hafskjold, & Smit, 2003; Tadros, 2013). The reduction in interfacial energy stabilizes emulsions by minimizing the tendency of the immiscible liquids to reduce the surface area and separate into a system that consists of a layer of oil phase (lower density) on top of a layer of aqueous phase (higher * Corresponding author. E-mail address: Sushil.Dhital@monash.edu (S. Dhital). Contents lists available at ScienceDirect Food Hydrocolloids journal homepage: http://www.elsevier.com/locate/foodhyd https://doi.org/10.1016/j.foodhyd.2020.106303 Received 20 June 2020; Received in revised form 28 August 2020; Accepted 1 September 2020