Edible insects as a novel source of lecithin: Extraction and lipid characterization of black soldier fly larvae and yellow mealworm

Edible insects with high fat and phosphorus content are a potential novel source of lecithin, however, studies on their minor lipids are limited. In this study, lecithin was extracted from black soldier fly larvae and yellow mealworm. Herein, the effects of lecithin extraction method, matrix and ultrasound pretreatment were explored based on the fatty acid composition and phospholipid profile with soy lecithin as a reference. The use of a wet matrix and ultrasound pretreatment increased the extraction efficiency of total PLs from both insects. Insect lecithin contained a considerable amount of sphingomyelin compared to soy lecithin. In insect lecithin, a total of 47 glycerophospholipid and sphingomyelin molecular species, as well as four molecular species of fatty acyl esters of hydroxy fatty acid, were detected. This study is the first comprehensive investigation of insects as a new source of lecithin with applications in food, cosmetics and in the pharmaceutical industry.

New Insight into Food-Grade Emulsions: Candelilla Wax-Based Oleogels as an Internal Phase of Novel Vegan Creams

Cream-type emulsions containing candelilla wax-based oleogels (EC) were analyzed for their physicochemical properties compared to palm oil-based creams (EP). The microstructure, rheological behavior, stability, and color of the creams were determined by means of non-invasive and invasive techniques. All the formulations exhibited similar color parameters in CIEL*a*b* space, unimodal-like size distribution of lipid particles, and shear-thinning properties. Oleogel-based formulations were characterized by higher viscosity (consistency index: 172-305 mPa·s, macroscopic viscosity index: 2.19-3.08 × 10-5 nm-2) and elasticity (elasticity index: 1.09-1.45 × 10-3 nm-2), as well as greater resistance to centrifugal force compared to EP. Creams with 3, 4, or 5% wax (EC3-5) showed the lowest polydispersity indexes (PDI: 0.80-0.85) 24 h after production and the lowest instability indexes after environmental temperature changes (heating at 90 °C, or freeze-thaw cycle). EC5 had particularly high microstructural stability. In turn, candelilla wax content ≥ 6% w/w accelerated the destabilization processes of the cream-type emulsions due to disintegration of the interfacial layer by larger lipid crystals. It was found that candelilla wax-based lipids had great potential for use as palm oil substitutes in the development of novel vegan cream analogues.

Modulating edible-oleogels physical and functional characteristics by controlling their microstructure

The influence of co-oleogelators like lecithin or hydrogenated lecithin together with the addition of dispersed water droplets to modulate the microstructure and thus the physical properties of glyceryl stearate (GS)-corn oil oleogels was investigated by thermal profile, microstructure, hardness, and oil binding capacity (OBC). The addition of β-carotene (βC) was also assessed. With lecithin, crystallization and melting temperatures were reduced, resulting in less-ordered crystal networks with a lower hardness and OBC, while with hydrogenated lecithin, the opposite effect was observed. In the presence of water, oleogels became harder but more brittle. Finally, βC acted as a crystal modifier increasing the hardness and OBC in the presence of lecithin, but decreased these parameters in hydrogenated lecithin-containing and water-filled oleogels. This study provides a better understanding on how the composition of GS-based oleogels can affect their physical properties.

Construction of interfacial crystallized oleogel emulsion with improved thermal stability

In this study, we reported a facile strategy to produce an interfacial crystallized oleogel emulsion for improved thermal stability. The interfacial crystallization of ceramide (non-interfacial active oleogelator) was achieved by addition of a surface active compound, which was demonstrated by interfacial rheology tests and polarized light microscopy. For successfully prepared interfacial crystallized emulsions, smaller particle size was observed when the gelator concentration was lower. However, better thermal stability was achieved when oleogelator concentration was higher than 1 wt%. Results from differential scanning calorimetry, X-ray diffraction and Fourier transform infrared spectroscopy suggested that the interfacial adsorption of ceramide was due to its co-crystallization with the emulsifier driven by hydrogen bonds formed by multiple sites. It provided appropriate crystallinity and steric repulsion for oleogel emulsions against oil droplet coalescence during heating process. This strategy greatly enriches oleogel emulsion formulations and their potential applications in food products involved with thermal treatment.

The nutritional functions of dietary sphingomyelin and its applications in food

Sphingolipids are common structural components of cell membranes and are crucial for cell functions in physiological and pathophysiological conditions. Sphingomyelin and its metabolites, such as sphingoid bases, ceramide, ceramide-1-phosphate, and sphingosine-1-phosphate, play signaling roles in the regulation of human health. The diverse structures of sphingolipids elicit various functions in cellular membranes and signal transduction, which may affect cell growth, differentiation, apoptosis, and maintain biological activities. As nutrients, dietary sphingomyelin and its metabolites have wide applications in the food and pharmaceutical industry. In this review, we summarized the distribution, classifications, structures, digestion, absorption and metabolic pathways of sphingolipids, and discussed the nutritional functioning of sphingomyelin in chronic metabolic diseases. The possible implications of dietary sphingomyelin in the modern food preparations including dairy products and infant formula, skin improvement, delivery system and oil organogels are also evaluated. The production of endogenous sphingomyelin is linked to pathological changes in obesity, diabetes, and atherosclerosis. However, dietary supplementations of sphingomyelin and its metabolites have been shown to maintain cholesterol homeostasis and lipid metabolism, and to prevent or treat these diseases. This seemly paradoxical phenomenon shows that dietary sphingomyelin and its metabolites are candidates for food additives and functional food development for the prevention and treatment of chronic metabolic diseases in humans.

Fabrication of chitosan-cinnamaldehyde-glycerol monolaurate bigels with dual gelling effects and application as cream analogs

In this study, chitosan-based bigels were fabricated, where glycerol monolaurate was added in MCT oil to produce a gelled lipid phase and cinnamaldehyde was included in the lipid phase in order to act as a crosslinking agent. The synergistic effect of pH on chemical crosslinking effects was investigated. The potential of using these bigels as an alternative to cream was also investigated. The pH of the aqueous phase played an important role in controlling the extent of the Schiff-base reaction promoted by cinnamaldehyde. At pH 3.8, the bigels formed were homogenous but at pH 5.0 and 5.5 they exhibited phase separation, which highlighted the importance of chemical crosslinking. To better mimic the properties of real cream, span 80 was added to create a more homogeneous and smoother structure of the bigels. These bigels might provide a healthy and more sustainable alterative to food products that contain plastic fats, like cream.

Glycolipid-Based Oleogels and Organogels: Promising Nanostructured Structuring Agents

Over the past few decades, the scientific community is actively involved in the development of edible structuring agents suitable for food, cosmetics, agricultural, pharmaceutical, and biotechnology applications. In particular, edible oil structuring using simple amphiphiles would be the best alternative for the currently used trans and saturated fatty acids, which cause deleterious health effects and cardiovascular problems. In this report, we have made an attempt to address the aforementioned consequences, by synthesizing a new class of structuring agents by a judicious combination of δ-gluconolactone and ricinoleic acid, compounds classified as GRAS, using simple steps in good yield. To our delight, the synthesized glycolipids self-assemble in a wide variety of vegetable oils and commercially viable glycerol, ethylene glycol, and polyethylene glycol via various intermolecular interactions to form a gel. The morphology of molecular gels was investigated by optical microscopy and FESEM analysis, which reveal the existence of a tubular architecture with a diameter ranging from 75 to 150 nm. Rheological studies disclosed the viscoelastic nature, thermal processability, and thixotropic behavior of both oleogels and organogels. Altogether, self-assembled oleogel and organogel reported in this paper would potentially be used in food, agricultural, cosmetics, pharmaceutical, and biotechnological applications.

Engineering water-induced ceramide/lecithin oleogels: understanding the influence of water added upon pre- and post-nucleation

A mixture of ceramide (CER) and lecithin (LEC) at specific ratios was capable of forming oleogels in sunflower oil triggered by adding a trace amount of water. It was noted that the addition of water at different temperatures (TW) resulted in different gelation behaviors and microstructures. To better illuminate the assembly mechanism at different TW, samples with water added at different TW (20 °C, 45 °C, 70 °C and 95 °C) were prepared. The viscoelastic properties, microstructures, and the crystal packing of these samples were investigated. It was observed that all samples prepared at TW of 20 °C and 95 °C formed gels, while most samples prepared at TW of 45 °C and 70 °C were too weak to form gels. Gels prepared at 95 °C were stronger but more fragile in texture compared to gels produced at 20 °C. The crystal morphology of gels drastically changed with TW. Spindle-shaped crystals were observed in gels prepared at low TW (20 °C), while gels prepared at high TW (95 °C) exhibited a network with packed oil droplets stabilized by lamellar shells together with fibrillar crystals in the bulk phase. X-ray diffractograms showed a different reflection peak (d-spacing of 14.5 Å) in gel prepared at 20 °C, compared to the d-spacing in oleogels with a single gelator (13.14 Å and 15.33 Å, respectively, for CER and LEC). Gel prepared at 95 °C showed two long-spacing characteristic peaks, which correspond to the characteristic peaks of CER gel (∼13 Å) and LEC gel (∼12 Å). Fourier transform infrared spectroscopy results indicated that the different gelation behaviors at different TW were mainly caused by vibrational changes in the amide bond of CER. Our hypothesized assembly mechanism can be concluded as: increasing TW resulted in the conversion of CER and LEC crystallization from co-assembly (TW = 20 °C) to self-sorting by individual gelators (TW = 95 °C). In this study, novel water-induced oleogels were produced by manipulating TW, and such information further assists the rational design of lipid-based healthy fat products.

Preparation of Protein Oleogels: Effect on Structure and Functionality

Among available structuring agents that have been used to provide solid properties to liquid oils, protein is a more recent candidate. Due to their nutritional value and high consumer acceptance, proteins are of special interest for the preparation of edible oleogels as an alternative for solid fats. Whereas the field of protein oleogelation is still rather new and just starts unfolding, several preparation methods have been demonstrated to be suitable for protein oleogel preparation. However, there is limited knowledge regarding the link between microstructural properties of the gels and macroscopic rheological properties, and the potential of such protein-based oleogels as a fat replacer in food products. In this review, we therefore provide an overview of various protein oleogel preparation methods and the resulting gel microstructures. Based on the different structures, we discuss how the rheological properties can be modified for the different types of protein oleogels. Finally, we consider the suitability of the different preparation methods regarding potential applications on industrial scale, and provide a short summary of the current state of knowledge regarding the behavior of protein oleogels as a fat replacer in food products.

Self-assembled lipids for food applications: A review

Lipids play an important role in human nutrition. Several foodstuffs can be manufactured from the simple, compound and derived lipids. In particular, the use of self-assembled lipids (SLs, e.g. self-assembled L-α-lecithin) has brought great attention for the development of tailored, tuned and targeted colloidal structures loading degradation-sensitive substances with valuable antimicrobial, antioxidant and nutraceutical properties for food applications. For example, polyunsaturated fatty acids (PUFAs) and essential oils can be protected from degradation, thus improving their bioavailability in general terms in consumers. From a nanotechnological point of view, SLs allow the development of advanced and multifaceted architectures, in which each molecule of them are used as building blocks to obtain designed and ordered structures. It is important to note before beginning this review, that simple and compound lipids are the main SLs, while essential fatty acids and derived lipids in general have been considered by many research groups as the bulk loaded substances within several structures from self-assembled carbohydrates, proteins and lipids. However, this review paper is addressed on the analysis of the lipid-lipid self-assembly. Lipids can be self-assembled into various structures (micelles, vesicular systems, lyotropic liquid crystals, oleogels and films) to be used in different food applications: coatings, controlled and sustained release materials, emulsions, functional foods, etc. SLs can be obtained via non-covalent chemical interactions, primarily by hydrogen, hydrophilic and ionic bonding, which are influenced by the conditions of ionic strength, pH, temperature, among others. This manuscript aims to give an analysis of the specific state-of-the-art of SLs for food applications, based primarily on the literature reported in the past five years.

Assembly pattern of multicomponent supramolecular oleogel composed of ceramide and lecithin in sunflower oil: self-assembly or self-sorting?

Ceramide (CER) is a novel food-grade organogelator with beneficial health effects. Lecithin (LEC) is not an effective gelator; however, it may alter the crystal morphology of the host gelator in a multicomponent system. In this paper, LEC and CER were mixed at various molar ratios in sunflower oil leading to different gelation behaviors. It was interesting since in this multicomponent system, gels formed when there was more less-effective gelator (LEC), while gels hardly formed when there was more effective gelator (CER). This drew our attention since there might not be only one kind of assembly mode between the LEC and the CER. A comprehensive rheological investigation was conducted. It was found that at specific ratios (6L4C and 5L5C), strong gels (G' > 1.0 × 105 Pa) formed with superior oil binding capacity (up to 99.84%). Meanwhile, these gels exhibited higher tolerance level to permanent deformation than the monocomponent gel. However, weak gels were observed off the optimal ratio (8L2C, 7L3C, 4L6C and 3L7C). The crystal morphology of gels drastically changed with change in gelator proportion. Short needle-like crystals and small rosette crystals were observed in 6L4C and 5L5C, respectively, while other samples exhibited spherulite-shaped crystals (8L2C, 7L3C, 4L6C, and 3L7C), which differed from any of the monocomponent gel structures (10L0C and 0L10C). Results from differential scanning calorimetry and polarized light microscopy suggested that the macroscopic properties are determined by the morphology and distribution of crystals rather than the crystallinity of the matrix. Fourier transform infrared spectroscopy results indicated the presence of van der Waals forces and the formation of hydrogen bonding between the phosphate of the LEC and the amide group of the CER. The above results indicated that the LEC and CER co-assembled at approximately equal molar ratio, and the redundant LEC or CER at other ratios self-sorted to combine with the co-assembled fibers by lateral association, leading to potentially different underlying microstructures. These multicomponent supramolecular oleogels with high tunability may further broaden their applicability in various healthy lipid-based product formats.

Development and evaluation of a novel oleogel system based on starch-water-wax-oil

A novel oleogel system was developed, and its characteristics and properties were investigated. The results indicate that a low-cost, low-fat and low hardness oleogel product was formed by potato starch, candelilla wax, oil, and distilled water. Specifically, the content of potato starch and candelilla wax in the oleogel system was 5 wt%. A potato starch/candelilla wax ratio from 1.22 to 5.67 led to the formation of a type II starch-lipid oleogel system, and the content of distilled water was 45 times the starch content. All the above-mentioned information demonstrated that starch/wax-based oleogels are a typical lipid system. They can reduce the content of wax and oil in oleogel systems, form oleogel products with low hardness values and exhibit great potential in the field of low-fat food and low-cost food industrial applications.

In vitrogastrointestinal digestibility of phytosterol oleogels: influence of self-assembled microstructures on emulsification efficiency and lipase activity

The objective of this study was to investigate the influence of a self-assembled microstructure on lipid digestibility of phytosterol (γ-oryzanol and β-sitosterol) oleogels, including the oil emulsification process and further lipolysis.