L-Lysine-Based Gelators for the Formation of Oleogels in Four Vegetable Oils.

Qiannan Li,Baocai Xu,Guiju Zhang,Jieying Zhang

doi:10.3390/molecules27041369

Qiannan Li, Baocai Xu + Show 2 more

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https://doi.org/10.3390/molecules27041369

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Abstract

Supramolecular oleogel is a soft material with a three-dimensional structure, formed by the self-assembly of low-molecular-weight gelators in oils; it shows broad application prospects in the food industry, environmental protection, medicine, and other fields. Among all the gelators reported, amino-acid-based compounds have been widely used to form organogels and hydrogels because of their biocompatibility, biodegradation, and non-toxicity. In this study, four Nα, Nε-diacyl-l-lysine gelators (i.e., Nα, Nε-dioctanoyl-l-lysine; Nα, Nε-didecanoyl-l-lysine; Nα, Nε-dilauroyl-l-lysine; and Nα, Nε-dimyristoyl-l-lysine) were synthesized and applied to prepare oleogels in four kinds of vegetable oils. Gelation ability is affected not only by the structure of the gelators but also by the composition of the oils. The minimum gel concentration (MGC) increased with the increase in the acyl carbon-chain length of the gelators. The strongest gelation ability was displayed in olive oil for the same gelator. Rheological properties showed that the mechanical strength and thermal stability of the oleogels varied with the carbon-chain length of the gelators and the type of vegetable oil. The microstructure of oleogels is closely related to the carbon-chain length of gelators, regardless of oil type. The highest oil-binding capacity (OBC) was obtained in soybean oil for all four gelators, and Nα, Nε-dimyristoyl-l-lysine showed the best performance for entrapping oils.

Highlights

Gel is a solid-like form of soft matter comprised of a liquid phase as the main component and a low concentration of a molecular gelator [1]
When the mass of the gelator is less than 2000 Da, the corresponding gel is defined as supramolecular gel or low-molecularweight gel (LMWG) [2,3,4,5,6], which is formed by small molecular gelators through supramolecular interactions, including hydrogen-bonding, van der Waals, π-stacking, coordination, donor-acceptor, and charge-transfer interactions
Ionic liquid gels, i.e., gels obtained in ionic liquids [8,9,10] and eutectogels, i.e., gels obtained in deep eutectic solvents [11,12] have been described

Summary

Introduction

Gel is a solid-like form of soft matter comprised of a liquid phase as the main component and a low concentration of a molecular gelator [1]. The mechanistic resemblance of oleogels to trans and saturated fats makes liquid oil gelation an ideal alternative in developing fat-based food products. In practical application, both the mechanical and aesthetic properties of oleogels are vital for food and other products. A lot of research has been conducted on oleogels, to discover the relationship between gelator structure, the nature of the oil, and gelation ability [17,18] It is still not well understood, due to the complicated systems. A better understanding of these oleogel systems will help to improve applications in cosmetic products, drug delivery and pharmaceuticals, and provide an alternative for making healthy foods that are free of trans fats and contain minimal saturated fats [19]

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