Palmitoylethanolamide gels edible oils
Introduction
Saturated and trans unsaturated fats are a public health issue because they represent a risk factor for cardiovascular diseases (Castelli et al., 1986, Martin et al., 1986, Hu et al., 2001, Mozaffarian et al., 2006, Brouwer et al., 2010, Clifton and Keogh, 2017). Public health authorities try to reduce their intake and tend to render the labelling of trans fat compulsory. Supported by this increasingly strengthening regulations, much research is now devoted to find replacement products of these solid fats. However, these fats play a major role to texture the food products: they form a network of microcrystals that endow the lipid phases with their mechanical properties. The sought substitution products should provide similar rheological properties. In this context, organogelators have gained increasing interest. These compounds self-associate in organic solvents to form 3D networks, which results in the formation of gels at mass fraction of a few percent. Gels made of such organogelators and vegetal liquid oils, comprising mainly cis-unsaturated acids and healthier, constitute good substitution products of solid fats (Scharfe and Flöter, 2020, Wesdorp et al., 2014, Zetzl and Marangoni, 2014). A few compounds are known for their ability to form edible oleogels: waxes (Toro-Vazquez et al., 2007, Dassanayake et al., 2009, Hwang et al., 2012), mixtures fatty alcohol and fatty acid (Gandolfo, Bot & Flöter, 2004), 12-hydroxystearic acid (12-HSA) (Elliger et al., 1972, Rogers, 2009, Rogers and Marangoni, 2008), mixtures of γ-oryzanol and sitosterol (Bot & Agterof, 2006) and ceramides (Rogers, Wright & Marangoni, 2009).
In this paper, we explore the possibility to form gels from edible oils and palmitoylethanolamide (PEA, Fig. 1). This simple molecule is endogenous, present in the mammalian brains, liver and muscles (Bachur, Masek, Melmon & Udenfriend, 1965). It was shown to have anti-inflammatory and analgesic properties (Bortolotti et al., 2012, Kuehl et al., 1957). In oral uptake by rats, it has a no effect level up to 1000 mg/body wt/day (Nestmann, 2017). This high level makes them interesting candidates to gel edible oils, especially if the concentration required to form a gel is a few weight percent. In the present contribution, we have explored the gelation ability of PEA was investigated in different solvents, including vegetable oils and found that it can form gels in the latter at concentration below 1 wt%. We have studied in details the gels of PEA in rapeseed oil. We have studied the transitions in this system by microDSC, turbidimetry and rheology and we have mapped the c-T binary phase diagram. Finally, the structure of the oleogels were investigated by scanning electron microscopy and FTIR.
Section snippets
Materials
Rapeseed Oil (Vita D’or), Olive oil (Carrefour) and Safflower oil (Mon-droguiste) were purchased in a local grocery shop. All the oils were refined. Palmitoyl chloride was purchased from Alfa Aesar (Thermo Fischer Scientific) and hydroxybenzotriazole from Acros Organics (Thermo Fischer Scientific). Ethanolamine was purchased from Sigma Aldrich. EDAC was purchased from Apollo Scientific.
Palmitoylethanolamide
A solution of palmitic acid (2.60 g, 10.12 mmol), hydroxybenzotriazole (140 mg, 1.01 mmol) and ethanolamine
Solubility and gelation
The structure of the studied compound is depicted in Fig. 1. PEA is able to form gels in alkanes (hexane, cyclohexane, trans-decalin and in several edible oils for wt. fraction of 0.5%. or higher: rapeseed, olive and safflower oil. At room temperature, PEA is insoluble in the oils; it is fully solubilized when the mixture is heated. When the solution is cooled back at room temperature, the gel forms. These gels are turbid and are stable for months. In this work, rapeseed oil was chosen for the
Conclusion
We have showed that PEA, a natural molecule well studied for its biological properties, is able to form stable gels in a variety of solvents, especially in rapeseed oil where, its binary phase diagram was established for a decade of concentration upon heating. The gel is made of large lamellar crystallites forming a network in the mixture and endowing it with its mechanical properties. These new organogels are of interest for food or cosmetics applications. The phase diagram shows a gap between
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
The facility of polymer characterization is acknowledged for the use of the UV and FTIR spectrometers. Anaïs de Maria is acknowledged for the FTIR measurements. Mélanie Legros is acknowledged for her help with microDSC. The electron microscopy facility and Marc Schmutz are acknowledged for their help. Thanks to Jean-Philippe Lamps for his help with syntheses. Guillaume Fleith is acknowledged for WAXS measurements. Funding This work was funded by the Institut Carnot MICA (Project Oleogel). D. S.
Bibliography (26)
- et al.
Fatty Acid Amides of Ethanolamine in Mammalian Tissues
Journal of Biological Chemistry
(1965) - et al.
A systematic review of the effect of dietary saturated and polyunsaturated fat on heart disease
Nutrition, Metabolism and Cardiovascular Diseases
(2017) - et al.
Serum Cholesterol, Blood Pressure, and Mortality: Implications from a Cohort of 361 662 Men
The Lancet
(1986) Novel structuring strategies for unsaturated fats – Meeting the zero-trans, zero-saturated fat challenge: A review
Food Research International
(2009)- et al.
13—Trans Fats Replacement Solutions in Europe
- et al.
10—Structured Emulsions and Edible Oleogels as Solutions to Trans Fat
- et al.
Palmitoylethanolamide Versus a Nonsteroidal Anti-Inflammatory Drug in the Treatment of Temporomandibular Joint Inflammatory Pain
Journal of Orofacial Pain
(2012) - et al.
Structuring of edible oils by mixtures of γ-oryzanol with β-sitosterol or related phytosterols
Journal of the American Oil Chemists’ Society
(2006) - et al.
Effect of Animal and Industrial Trans Fatty Acids on HDL and LDL Cholesterol Levels in Humans – A Quantitative Review
PLOS ONE
(2010) - et al.
Incidence of Coronary Heart Disease and Lipoprotein Cholesterol Levels: The Framingham Study
JAMA
(1986)
Jamming transition in solutions containing organogelator molecules of amino-acid type: Rheological and calorimetry experiments
Soft Matter
Physical Properties of Rice Bran Wax in Bulk and Organogels
Journal of the American Oil Chemists’ Society
Thickening action of hydroxystearates in peanut butter
Journal of the American Oil Chemists Society
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