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Edible “Oleocolloids”: The Final Frontier in Food Innovation? Ashok R. Patel* Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Gent, Belgium challenging because there are only limited food-grade materials that have the required properties and functionalities to create and stabilize oleocolloids. Moreover, the reformulated products will show some loss of functionality and may not be able to match the characteristics of conventionally formulated food products. Additionally, significant reworking of the processing steps will be required at the industrial end to successfully translate laboratory-scale research to product development. Looking at the evolution of lipid-based emulsified food products over the years, it can be seen that there has been a significant technological development in the area of reformulating conventional food products such as margarines and spreads to decrease the total fat content while maintaining the macrostructure and texture. This has been achieved by structuring the aqueous dispersed phase using biopolymers such as starch or gelatin.2 The reformulation concept, however, is focused on decreasing the total fat content rather than improving the fatty acid profile of the product. Consequently, “Oleocolloids” is a term used here to represent a broad range of the level of saturated fats in the reformulated products is still oil continuous soft matter systems comprising colloids at an rather high. To reduce the proportion of saturated fats in food interface of complex fluids and phase-separated states of matter formulations, two avenues can be explored: colloidal structuring such as oleogels; biphasic colloids where water droplets or air of edible liquid oils (oleogelation) and utilizing innovative bubbles are dispersed in an oil continuous medium (indirect dispersion technologies that rely on creating biphasic systems emulsions and oleofoams respectively); complex colloids such (e.g., complex emulsions and oleofoams, etc.). Both of these are as foamed oleogels and oil in water in oil (O/W/O) emulsions; aimed at achieving the desired texture and functional and layered structural matrices embedding a large volume of macroproperties of products without relying on the use of liquid oil (oleofilms). Oleocolloids or oil continuous colloidal solid fats. systems (Figure 1) have not received the same level of However, the challenges are manifold as there is a significant attention as water continuous systems when it comes to lack of understanding of solute−solvent interactions in innovation in the food sector. The main reasons for this lack of hydrophobic mediums such as edible oils. Hence, there is an interest include (1) the limited market needs (i.e., there is only urgent need for investigating the links between the molecular features and parameters such as solubility, self-assembly a narrow range of food products that are based on oil (process by which individual molecules form defined continuous systems) and (2) the relative ease of historically aggregates), and self-organization (a process by which the formulating these products with the help of trans-fats (or aggregates create higher-ordered structures) of different saturated fats from natural sources) and synthetic emulsifiers categories of solutes in liquid oil while gathering information (such as monoglycerides, polyglycerol polyricinoleate, etc.). about the physical (e.g., dielectric constant, ε), solvatochromic However, a combination of factors including recent policy (e.g., polarity parameter, ET), and thermodynamic (e.g., changes in United States with regard to removal of trans-fats Hilderbrand solubility parameter, δ) properties of solvents from food products, rising concerns among consumers about (i.e., edible oils).3 the negative effect of saturated fat consumption and the In addition, innovation in the dispersion techniques could ecological damage caused by palm oil usage, and, more recently, assist in the formulation of novel complex colloids such as high the industrial drive toward more clean-labeled products internal phase emulsions, double emulsions (O/W/O), (products formulated with natural ingredients) have together oleofoams, and oleofilms, which could be used for reformulaprovided new motivations for food material scientists to focus tion of existing food products or to develop new product on innovations in formulating oil continuous systems with the formats. aim of improving the nutritional profile of food products (transStudies done so far in this field are mainly exploratory in fat-free, low in saturated fats, and high in unsaturated fats), nature. To commercially exploit some of these potential reducing the requirement of palm oil in food formulations, and systems for food product formulation, extensive developmental developing clean-labeled products (relying on the replacement 1 of synthetic emulsifiers with biopolymers). Although the drive for research is stronger than ever before, Received: March 29, 2017 Published: April 21, 2017 finding feasible solutions to these formulation issues is © 2017 American Chemical Society
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DOI: 10.1021/acs.jafc.7b01421 J. Agric. Food Chem. 2017, 65, 3432−3433
Journal of Agricultural and Food Chemistry
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ACKNOWLEDGMENTS I thank Wahyu Wijaya for his work on oleofilms, which will soon be published externally. REFERENCES
(1) Patel, A. R. Alternative Routes to Oil Structuring; Springer International Publishing: New York, 2015. (2) Muschiolik, G.; Dickinson, E. Double emulsions relevant to food systems: preparation, stability, and applications. Compr. Rev. Food Sci. Food Saf. 2017, DOI: 10.1111/1541-4337.12261. (3) Lan, Y.; Corradini, M. G.; Weiss, R. G.; Raghavan, S. R.; Rogers, M. A. To gel or not to gel: correlating molecular gelation with solvent parameters. Chem. Soc. Rev. 2015, 44, 6035−6058. (4) Patel, A. R.; Mankoc, B.; Bin Sintang, M. D.; Lesaffer, A.; Dewettinck, K. Fumed silica-based organogels and ‘aqueous-organic’ bigels. RSC Adv. 2015, 5, 9703−9708. (5) Patel, A. R. Surfactant-free oil-in-water-in-oil emulsions stabilized solely by natural components-biopolymers and vegetable fat crystals. MRS Adv. 2017, DOI: 10.1557/adv.2017.33. (6) Patel, A. R. Stable ‘arrested’ non-aqueous edible foams based on food emulsifiers. Food Funct. 2017, DOI: 10.1039/C7FO00187H.
Figure 1. Representative images of oleocolloids (clockwise from top left): microstructure of margarine based on indirect emulsion (water droplets dispersed in crystalline network of oil continuous phase) (unpublished work); reduced-fat margarine where dispersed water phase is structured with starch (unpublished work); picture of liquid oil structured into transparent oleogel (adapted with permission from ref 4; copyright 2015 Royal Society of Chemistry); microstructure of freeze-fractured double-emulsion droplet showing a high encapsulation of inner oil droplets in a surfactant-free O/W/O double emulsion (adapted with permission from ref 5; copyright 2017 Cambridge Core); microstructure of oleofoam (air bubbles stabilized by interfacial accumulation of crystalline particles) (adapted with permission from ref 6; copyright 2017 Royal Society of Chemistry); a flexible oleofilm containing >98 wt % liquid sunflower oil (unpublished work).
work within the framework of industrial R&D will be required. A complete replacement of saturated fats in food products is not practically feasible at this stage, but some of the progress made in the field of oil structuring can help us with the partial replacement of saturated fats by formulating the so-called hybrid systems. At the same time, using innovation in transforming the processing techniques can help us develop new product formats with the possibility of decreasing saturated fat, overall calories, and replacement of synthetic emulsifiers. Given the lack of progress in this area and the lack of feasible options to fulfill the unmet industrial needs, it is an ideal time for researchers from multidisciplinary fields to take up the challenge of innovating in the area of edible oleocolloids.
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AUTHOR INFORMATION
Corresponding Author
*Present address: International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal. E-mail:
[email protected],
[email protected]. Phone: + 351 253 140 112-2370. Mob. no. 00351938173331. ORCID
Ashok R. Patel: 0000-0002-3840-2473 Funding
I acknowledge financial support from a Marie Curie Career Integration Grant within the 7th European Community Framework Programme. Notes
The author declares no competing financial interest. 3433
DOI: 10.1021/acs.jafc.7b01421 J. Agric. Food Chem. 2017, 65, 3432−3433
