Food & Function PAPER Cite this: Food Funct., 2018, 9, 1755 Received 11th November 2017, Accepted 8th February 2018 DOI: 10.1039/c7fo01775h rsc.li/food-function Synergistic interactions between lecithin and fruit wax in oleogel formation Paula K. Okuro, a Iris Tavernier, b Mohd D. Bin Sintang, b,c Andre G. Skirtach, d António A. Vicente, e Koen Dewettinck b and Rosiane L. Cunha * a In this study, the effect of lecithin (LEC) on the crystallization and gelation of fruit wax (FW) with sunflower oil was researched. A synergistic effect on the gel strength was observed at FW : LEC ratios of 75 : 25 and 50 : 50, compared to the corresponding single component formulations (100 : 0 and 0 : 100). Even below the critical gelling concentration (C g ) of FW, the addition of lecithin enabled gel formation. Lecithin affected the thermal behavior of the structure by delaying both crystallization and gel formation. The phospholipid acted as a crystal habit modifier changing the microstructure of the oleogel, as was observed by polarized light microscopy. Cryo-scanning electron microscopy revealed a similar platelet- like arrangement for both FW as a single oleogelator and FW in combination with LEC. However, a denser structure could be observed in the FW : LEC oleogelator mixture. Both the oil-binding capacity and the thixotropic recovery were enhanced upon lecithin addition. These improvements were attributed to the hydrogen bonding between FW and LEC, as suggested by Raman spectroscopy. We hypothesized that lecithin alters the molecular assembly properties of the FW due to the interactions between the polar moieties of the oleogelators, which consequently impacts the hydrophobic tail (re)arrangement in gelator–gelator and solvent–gelator interactions. The lipid crystal engineering approach followed here offered prospects of obtaining harder self-standing structures at a lower oleogelator concentration. These synergistic interactions provide an opportunity to reduce the wax concentration and, as such, the waxy mouthfeel without compromising the oleogel properties. Introduction Semi-solid and solid fats provide the desired structural, func- tional and sensory attributes to many food products. The con- ventional approach for oil structuring involves the formation of a colloidal crystal network consisting of triglycerides. 1 These triglycerides often contain saturated and/or trans-fatty acids which have been related to negative health effects upon con- sumption. 2 Following the rising health-related consumer con- cerns and the narrowing regulatory legislation for food pro- ducts, the development of new materials has been pursued by the food industry and researchers to partially replace saturated fat and completely replace partially hydrogenated oils. From this perspective, the use of oleogelators has emerged as an alternative for oil structuring. 3 These compounds can create a supramolecular organization comprised of randomly entangled fiber-like or platelet-like structures which entrap the liquid oil in a non-flowing con- dition, especially through the surface and capillary forces. 4,5 Oleogelators can be classified into (i) colloidal systems such as emulsion droplets in high internal phase emulsions and in- organic particles, 6–8 (ii) polymeric oleogelators such as ethyl- cellulose, 9 (iii) low molecular weight compounds that self- assemble into fibrous networks (SAFINs), strands, tubules, reverse micelles or mesophases such as phospholipids and sterols 10,11 and (iv) crystalline particles, including mono- and diglycerides, fatty alcohols, and natural waxes. 1,12–15 Natural plant- and animal-based waxes are commercially available at a low cost. Furthermore, a relatively low amount is required for gelation. 13,14,16 Interestingly, wax-based oleogels are thermoreversible and waxes can function either as an oleo- gelator or as an emulsifier in emulsions. 12,17,18 Waxes have diverse chemical composition, which generally includes wax esters, hydrocarbons, fatty acids, fatty alcohols, mono-, di-, a Laboratory of Process Engineering, Department of Food Engineering, Faculty of Food Engineering, University of Campinas, UNICAMP, CEP: 13083-862, Campinas, SP, Brazil. E-mail: rosiane@unicamp.br b Vandemoortele Centre Lipid Science and Technology, Laboratory of Food Technology and Engineering, Department of Food Safety and Food Quality, Ghent University, Coupure Links 653, 9000 Gent, Belgium c Department of Food Technology and Bioprocess, Faculty of Food Science and Nutrition, University Malaysia, Sabah, Malaysia d Department of Molecular Biotechnology, Ghent University, Coupure Links 653, 9000 Gent, Belgium e Centre of Biological Engineering, Campus de Gualtar, University of Minho, 4710- 057 Braga, Portugal This journal is © The Royal Society of Chemistry 2018 Food Funct. , 2018, 9, 1755–1767 | 1755 Published on 09 February 2018. Downloaded by UNIVERSIDAD ESTADUAL DE CAMPINAS on 22/05/2018 16:35:03. View Article Online View Journal | View Issue