Pickering Particles Prepared from Food Waste

Abstract

In this paper, we demonstrate the functionality and functionalisation of waste particles as an emulsifier for oil-in-water (o/w) and water-in-oil (w/o) emulsions. Ground coffee waste was chosen as a candidate waste material due to its naturally high content of lignin, a chemical component imparting emulsifying ability. The waste coffee particles readily stabilised o/w emulsions and following hydrothermal treatment adapted from the bioenergy field they also stabilised w/o emulsions. The hydrothermal treatment relocated the lignin component of the cell walls within the coffee particles onto the particle surface thereby increasing the surface hydrophobicity of the particles as demonstrated by an emulsion assay. Emulsion droplet sizes were comparable to those found in processed foods in the case of hydrophilic waste coffee particles stabilizing o/w emulsions. These emulsions were stable against coalescence for at least 12 weeks, flocculated but stable against coalescence in shear and stable to pasteurisation conditions (10 min at 80 °C). Emulsion droplet size was also insensitive to pH of the aqueous phase during preparation (pH 3–pH 9). Stable against coalescence, the water droplets in w/o emulsions prepared with hydrothermally treated waste coffee particles were considerably larger and microscopic examination showed evidence of arrested coalescence indicative of particle jamming at the surface of the emulsion droplets. Refinement of the hydrothermal treatment and broadening out to other lignin-rich plant or plant based food waste material are promising routes to bring closer the development of commercially relevant lignin based food Pickering particles applicable to emulsion based processed foods ranging from fat continuous spreads and fillings to salad dressings.

Centrifugal fractionation of softwood extracts improves the biorefinery workflow and yields functional emulsifiers

“…32 Moreover, stable oil-in-water emulsions can be obtained using lignincontaining food grade materials such as cocoa particles 34 and spent coffee grounds. 35 It is evident that hemicelluloses and lignin, extracted using, for example, the PHWE method, can be used to increase the sustainability of the food chain because woods can be grown on, for example, non-arable land, introducing a wood-to-food approach.…”

Encapsulation of Vitamin D3 in Pickering Emulsion Stabilized by Nanofibrillated Mangosteen Cellulose: Effect of Environmental Stresses

“…Most emulsions in the food industry are stabilized by molecular emulsifiers, but there is growing interest in the use of particulate emulsifiers due to their potential benefits in improving emulsion stability (Winuprasith & Suphantharika, 2015). Emulsions stabilized by particles are known as Pickering emulsions, and may have a wide range of applications in the food, cosmetic, and pharmaceutical industries (Gould, Garcia-garcia, & Wolf, 2016). Particulate emulsifiers bind almost irreversibly to the oil droplet surfaces due to their high attachment energy, which makes Pickering emulsions highly stable against coalescence (Chevalier & Bolzinger, 2013;Erickson, 2009).…”

Interest of Pickering Emulsions for Sustainable Micro/Nanocellulose in Food and Cosmetic Applications

“…Other vegetal materials, as ground coffee wastes [ 77 ], apple pomace, or oat bran [ 78 ] were also used to stabilize PEs without alkali treatment or bleaching. Ground coffee contains a lot of hemicellulose, but also lignin, protein and cellulose [ 79 ], apple pomace is rich in cellulose, pectin, lignin, hemicellulose and protein [ 80 ], and oat bran contains dietary fibers, as cellulose and lignin, but also starch and protein [ 81 ].…”

“…However, to obtain stable PEs, particles content was generally higher than with purified nanocellulose. For instance, stable PEs, formulated with 1:1 sunflower oil/water ratio, were obtained with a minimum of 8% ground coffee [ 77 ].…”