Rice husk silica for the stabilization of food-grade oil-in-water (O/W) emulsions

Abstract

Food is a basic essential for human beings. Therefore, the overall product quality such as nutrition, texture, appearance, taste, and stability are of fundamental considerations. To provide food with good stability along with desirable texture and appearance, stabilizers have been usually added into processed food products. Stabilizers are generally added into processed foods containing mixtures of aqueous and oil phases. It functions as an enhancement to food texture and appearance, since it helps produce a stable emulsion. Emulsifiers are among the stabilizers which promptly enhance the stability of water-in-oil (W/O) or oil-in-water (O/W) emulsionebased food products. Emulsifiers consist of polar heads and nonpolar tails, and they reorient themselves on the interface of oil and water emulsion to lower the surface tension arising between those two immiscible phases, thus enabling the stable dispersion of one phase into another. Natural emulsifiers have been replaced by synthetic ones for a long time since they can be mass produced and are therefore lower in price. However, there has in recent times been a growing popularity in natural emulsifiers due to the undesirable health effects of synthetic emulsifiers over the longterm such as obesity and related issues (Simmons et al., 2014). On the other hand, natural emulsifiers have low toxicity, are easily degradable, biodegradable, are effective in extreme conditions, and are able to be reused via regeneration, so that they enjoy preference in the food industry despite their higher price (Koglin et al., 2010). Solid particles have existed in emulsion formulation for many years, such as those used in the food, oil, pharmaceutical, and agrochemical industries (Binks, 2002). They are believed to enhance stability to some extent. In many food and foam emulsions stabilized mainly through proteins and phospholipids, solid particles play a significant role for necessary stabilization, such as ice crystals in ice cream and the particles of fat in whipping cream (Binks, 2002). The use of colloidal particles to stabilize emulsions and foams known as the Pickering emulsion has been known for at least a century (Aveyard et al., 2003). Ramsden (1903) concluded that the existence of viscous material at the two immiscible liquids' interfaces contributed, in part, to the stability of many emulsions. Solid and stabilized emulsion was formed, thanks to finely divided solids dispersed between the interfaces of oil and water. Pickering (1907) observed that colloid particles dampened more easily by CHAPTER Biopolymer-Based Formulations.

Enhancement of the Stability of W/O/W Double Emulsion by Chitosan Modified Rice Husk Silica

“…Several particles which have been used for Pickering emulsions were silica, clays, polymer latex, magnetic particles, graphene, and polymethylpolymethylmethacrylate particles (Lee & Choi, 2018;Bao et al, 2019). The use of silica for the stabilization of O/W emulsion has been widely investigated (Sapei et al, 2017a;Sapei et al, 2017b;Sapei et al, 2018;Sapei, 2020). However, the use of bare silica was not effective and had to be combined with the use of polymeric emulsifiers to help its adsorption onto the interfacial layers (Pichot et al, 2012;Sapei et al, 2017a;Sapei et al, 2017b).…”

“…At higher pH of about 7-8, dissolved chitosan was able to strengthen the interfacial layer O/W emulsion due to the polymer chains aggregation (Mwangi et al, 2016). Silica accumulated in living tissues generally referred to as biosilica was amorphous and tended to be hydrophilic due to the presence of hydroxyl groups on their surface (Sapei et al, 2008;Dhaneswara et al, 2019;Sapei, 2020). It is well known that natural silica particles are negatively charged in pure water.…”