Development of an Antioxidative Pickering Emulsion Gel through Polyphenol-Inspired Free-Radical Grafting of Microcrystalline Cellulose for 3D Food Printing

Abstract

The manufacture of next-generation 3D-printed foods with personalized requirements can be accelerated by in-depth knowledge of the development of a multifunctional biopolymeric-based ink. As a fat replacer in the food industry, microcrystalline cellulose (MCC) has the potential to address the growing need for sustainable healthy reduced-fat 3D printed foods. The modification of MCC structure by polyphenols gives the way to produce a multifunctional antioxidative Pickering emulsion with improved emulsifying properties. In this study, different types of polyphenols, including gallic acid (GA), tannic acid (TA), and cyanidin-3- O -glucoside (C3G), were individually used to synthesize the grafted MCC- g -polyphenol conjugates by the free-radical grafting method. Then, the antioxidative grafted microconjugates were added to a soy protein-based emulsion gel to partially substitute its oil, and each Pickering emulsion gel variant was printed through an extrusion-based 3D printing system. Emulsifying properties and antioxidant character of MCC were proven to be enhanced after the fabrication of grafted microconjugates. Compared to MCC- g -TA, MCC- g -GA and MCC- g -C3G could efficiently improve the stability of a reduced-fat soy-based emulsion gel upon storage. Moreover, the reduced-fat soy-based emulsion gel containing grafted microconjugates endowed a characteristic shear-thinning behavior with a gel-like structure and superlative thixotropic properties. Following the printing, the antioxidative Pickering emulsion gels containing grafted microconjugates produced well-defined 3D structures with superior lubrication properties. This study demonstrated that the grafting of polyphenols onto MCC could enhance bioactive properties and improve emulsifying performance of MCC, making it a useful component in the development of personalized functional foods.

A Promising Therapeutic Soy-Based Pickering Emulsion Gel Stabilized by a Multifunctional Microcrystalline Cellulose: Application in 3D Food Printing

“…It has been reported that there is a slight change in the spatial structure and unfolding of the cellulose upon the interaction of functional groups of GA with MCC. 10 As Figure 2 d reveals, the intensity of diffraction peaks decreased more upon the development of a grafted MCC/GA/LAE conjugate, whose RCD dropped down to 58%. The XRD diffractogram showed that the typical MCC peak (2θ = 22.9°) altered to a more diffused peak, showing a reduction in the crystallinity.…”

“…This could imply an increase in the amphiphilicity of the system upon the grafting process and also the formation of complex coacervates between MCC and LAE. 10 It was stated that the interaction of LAE with other negatively charged molecules leads to the formation of complex coacervates. 29 This finally decreases the efficiency of LAE and therefore reduces the minimum inhibitory concentration of the LAE in certain food and pharmaceutical applications.…”

“…It was reported that polyphenol oxidation and oligomerization are developed after the grafting of GA onto the MCC backbone. 10 This enlarges the size of the conjugated compound of GA, contributing to an increase in the electron-donating groups. Thus, the GA-coated MCC and MCC/GA/LAE conjugate have more biological stability than the free GA. We assume then that these products, with their swollen supramolecular structure, could capture the free radicals more successfully compared to the small GA molecules.…”

“…This might be explained by the existence of higher amounts of hydrophobic/hydrophilic regions in Pickering emulsion gels. 10 In this situation, a strong interaction could be developed between comparable groups in the adjacent droplets/particles. 5 …”

“…Regarding the 3ITT, the final viscosity transients expose the changes in the structural levels of the system once the shear rate is suddenly stepped up or down. 10 Thus, a change in the viscosity of Pickering emulsion gel, after application of a stepwise shear rate, is related to its viscoelasticity and recovery compliance resulting from its structures. 5 In the second interval (with a steady shear rate of 80 s –1 ), a marked reduction in viscosity was observed due to the breaking up of the high levels of interconnected structures in the Pickering emulsion gels ( Figure 3 e).…”