Cellulose as a Natural Emulsifier: From Nanocelluloses to Macromolecules

Abstract

During the last decade, cellulose structural features have been revisited, with particular focus on its structural anisotropy (amphiphilicity) and interactions determining its recalcitrance to dissolution. Evidences for cellulose amphiphilicity are patent, for instance, in its capacity to adsorb at oil–water interfaces, thus being capable of stabilizing emulsions. This behavior is observable in all its forms, from cellulose nanoparticles to macromolecules. This chapter is divided into two main parts; first, the fundamentals of emulsion formation and stabilization will be introduced, particularly focusing on the role of natural emulsifiers. Secondly, the emerging role of cellulose as a natural emulsifier, where the ability of cellulose to form and stabilize emulsions is revisited, from cellulose nanoparticles (Pickering-like effect) to macromolecules (i.e., cellulose derivatives and native molecular cellulose).

Perspectives on the Lindman Hypothesis and Cellulose Interactions

“…Cellulose is a versatile source of natural emulsifiers and can be utilized as such over the whole hierarchical size range, from cellulose particles and gels to macromolecules; see Figure 6 . The capability of all forms of cellulose to adsorb at oil–water interfaces and stabilize emulsions has been reported in the literature [ 117 , 118 ]. This phenomenon indirectly evidences the significance of the hydrophobic interactions between cellulose molecules and how they can affect the dissolution and regeneration of cellulose.…”

Xylitol

“…In addition, tomato is also processed to produce tomato-based products such as canned tomatoes, tomato juice, ketchup, and others 2 . Regarding its compounds, there are a wide variety of properties in tomato stems and leaves, such as adhesive, thickener, emulsifier, gelling agent, and others (Costa et al 2021;Khan, Lee, and Kim 2019;Reichembach and Petkowicz 2021). These compounds have several applications, such as electrical insulators, sponges, glues, biofuels, biopolymers, films, coatings, and leather, among others (Farhat et al 2017b;Ferreira et al 2015;Jusner et al 2021;Qaseem, Shaheen, and Wu 2021;Reichembach and Petkowicz 2021;Singh and Kumar 2019;Yang et al 2021;Yang, Xu, and Yang 2015).…”

Encapsulation of Thymol and Eugenol Essential Oils Using Unmodified Cellulose: Preparation and Characterization

“…Cellulose is a linear polysaccharide, a homopolymer of glucose, found in all plants and characterized by a semicrystalline fibrillar structure comprised of highly ordered crystalline domains separated by disordered amorphous regions [ 24 ]. Its intrinsic amphiphilic character, as well as its mechanical strength, motivated evaluation of its application as an emulsifier or encapsulating material which can form a coating shell at oil–water interfaces [ 25 , 26 ]. Under appropriate conditions, “Pickering emulsions” can be formed by assembly of nano- or micro-crystalline cellulosic solids at the oil-water interface [ 16 , 27 , 28 ].…”

“…Under appropriate conditions, “Pickering emulsions” can be formed by assembly of nano- or micro-crystalline cellulosic solids at the oil-water interface [ 16 , 27 , 28 ]. Alternatively, cellulose can form a continuous amorphous coating when applied from solution by high shear mixing with oil and water [ 25 , 29 ]. In such case, encapsulation has been suggested to occur upon cellulose regeneration from solution at the interface between the cellulose solution and the aqueous medium [ 29 ].…”

“…Waste material from textiles or the paper industry was also shown to be a suitable raw material for this process [ 30 ]. Several works have studied encapsulation of EOs by modified cellulose (e.g., methyl-cellulose, ethyl-cellulose, carboxy-methyl-cellulose or hydroxypropyl-cellulose) [ 25 , 33 ]. However, it is of interest to apply unmodified cellulose for EOs encapsulation, to eliminate the need for chemical modification.…”