Effect of oil unsaturation and wax composition on stability, properties and food applicability of oleogels

Effects of polyunsaturated fatty acid and diacylglycerol on the crystallization behaviors of palm-based oil

Diacylglycerol (DAG) is a novel functional structural lipid, but its application in base oils remains underexplored. This research investigated the effect of three liquid oils (groundnut oil, corn oil, and flaxseed oil), with varying polyunsaturated fatty acid (PUFA) (39.60, 69.50, and 77.65 %) and DAG content (0.00, 40.00, 80.00 %), on the crystallization behaviors of palm-based oil. DAG (40.00 %), obtained through enzymatic glycerolysis and molecular distillation, was found to stabilize the binary system with good compatibility and fine crystal structure. "Liquid" DAG played a dual role: diluting solid lipids, and promoting crystallization. Increasing DAG content led to larger crystalline domain size, while higher PUFA content accelerated crystallization and increased crystal orderliness, though decreasing crystal density. These results demonstrated the clear influence of PUFA and DAG content on palm-based oil crystallization. This knowledge can guide the utilization of different unsaturated DAGs for tailored fat crystallization in food application.

Effect of vegetable oil unsaturation and minor polar components on the physical properties of rice bran wax oleogels

For the practical application of oleogels and to produce oleogels with consistent properties, a full understanding of the factors affecting properties of oleogels is necessary. This study aimed to understand the effects of type of oil and minor components in oils on the properties of 3% and 7% rice bran wax (RBW) oleogels, which were prepared with 12 vegetable oils with different degrees of unsaturation as well as the same oils where polar compounds were removed (stripped oils). Correlation coefficients of iodine values (IVs) of oils with the firmness of 3% and 7% RBW stripped oil oleogels were -0.632 and -0.499, respectively, indicating that the gel strength decreased with increasing unsaturation of oil. The gel strength increased after removing polar compounds in oil for all the oleogel samples. Higher unsaturation of oil resulted in higher solid wax contents (SWCs) in 7% RBW stripped oil oleogels (r = 0.617), which, however, did not affect the gel strength. Very thin, large platelet wax crystals were observed under phase-contrast microscopy, which were almost identical across the oleogel samples. The permeation of dyed oil through oleogels was faster with unstripped oil oleogels than stripped oil oleogels, and the negative correlation between the color permeation rate and the firmness of oleogels was significant (r = -0.602 at Day 28) indicating that defects in the three-dimensional crystal network is an important factor for the gel strength. This study found several important factors affecting the physical properties of RBW oleogels, which can be applied to their practical applications. PRACTICAL APPLICATION: For the practical application of oleogels, factors affecting properties of oleogels must be fully understood so that the quality of oleogel-containing food products could be well controlled. Although oil is the major component of oleogels, the effect of the type of oil on oleogel properties was not well understood to date, and this study revealed very important relationships between oil properties and oleogel properties, which can be applied to the production of oleogel-containing products. The major findings are that gel strength was higher with lower unsaturation of oil and less polar compounds in oil and that melting temperature was higher with higher unsaturation of oil.

Development of oleogel by structuring the blend of corn oil and sunflower oil with beeswax to replace margarine in cookies

Oleogel significantly affects the product's sensory properties, texture, and shelf life. The goal of this study was to create oleogel by combining corn oil and sunflower oil and utilizing beeswax as a structural agent. A variety of physicochemical analyses were done to evaluate the quality of oleogel, including peroxide value, iodine value, saponification value, fatty acid, rheological parameters and firmness. Different percentages of oleogel, ranging from 0% to 75%, were used to substitute margarine in cookies. The cookies' quality was evaluated using proximate analysis, color analysis, texture analysis, calorific value, and sensory analysis. The study yielded substantial results by finding the ideal margarine-to-oleogel mix ratio, allowing for the manufacturing of high-quality cookies with a greater degree of unsaturation. Cookies with oleogel showed higher levels of unsaturation and better properties, making them the preferred option among consumers.

Recent Advances in Lipid Crystallization in the Food Industry

This review discusses fundamental concepts of fat crystallization and how various processing conditions such as crystallization temperature, cooling rate, and shear or agitation affect this process. Traditional methods used to process fats, such as the use of scraped surface heat exchangers, fractionation, and interesterification, are described. Parameters that affect fat crystallization in these systems, such as shear, crystallization temperature, type of fat, and type of process, are discussed. In addition, the use of minor components to induce or delay fat crystallization based on their chemical composition is presented. The use of novel technologies, such as high-intensity ultrasound, oleogelation, and high-pressure crystallization is also reviewed. In these cases, acoustic and high-pressure process parameters, the various types of oleogels, and the use of oleogelators of differing chemical compositions are discussed. The combination of all these techniques and future trends is also presented.

Characterization and classification of oleogels and edible oil using vibrational spectroscopy in tandem with one-class and multiclass chemometric methods

Oleogel represents a promising healthier alternative to act as a substitute for conventional fat in various food products. Oil selection is a crucial factor in determining the technological properties and applications of oleogels due to their distinct fatty acid composition, molecular weight, and thermal properties, as well as the presence of antioxidants and oxidative stability. Hence, the relevance of monitoring oleogel properties by non-destructive, eco-friendly, portable, fast, and effective techniques is a relevant task and constitutes an advance in the evaluation of oleogels quality. Thus, the present study aims to classify oleogels rapidly and reliably, without the use of chemicals, comparing two handheld near infrared (NIR) spectrometers and one portable Raman device. Furthermore, two different multivariate methods are compared for oleogel classification according to oil type. Three types of oleogels were prepared, containing 95 % oil (sunflower, soy, olive) and 5 % beeswax as a structuring agent, melted at 90 °C. Polarized light microscopy (PLM) images were acquired, and fatty acid composition, peroxide index and free fatty acid content were determined using official methods. A total of 240 oleogel and 92 oil spectra were obtained for each instrument. After spectra pretreatment, Principal Component Analysis (PCA) was performed, and two classification methods were investigated. The Data Driven - Soft Independent Modelling of Class Analogy (DD-SIMCA) and Partial Least Squares Discriminant Analysis (PLS-DA) models demonstrated 95 % to 100 % of accuracy for the external test set. In conclusion, the use of vibrational spectroscopy using handheld and portable instruments in tandem with chemometrics showed to be an efficient alternative for classifying oils and oleogels and could be extended to other food samples. Although the classification of vegetable oils by NIR is widely used and known, this work proposes the classification of different types of oil in oleogel matrices, which has not yet been explored in the literature.

Analysis of Oleogel Volatile Profile Formation under Ultrasonic Treatment

Under certain conditions, ultrasonic treatment of certain foods and ingredients can contribute to the appearance of an extraneous odor, which is not usual for them, especially in fat-containing products. Since the food sector uses high-intensity ultrasound to control the crystallization of fats, the development of foreign smells and secondary fat oxidation products may impact the quality and safety of such items. In this work, we studied the volatile compounds' profiles of oleogels structured with individual fractions of beeswax using ultrasonic treatment. For this work, six samples of oleogels were obtained. Sunflower oil was used as a fatty base, and three fractions of beeswax were used as gelators: hydrocarbon fraction (>99%), monoester fraction (>95%), and a mixture fraction of wax di- and triesters (10.1%), free fatty acids (40.1%), and free fatty alcohols (49.8%). The influence of ultrasonic treatment on the properties of oleogels was assessed using light microscopy in polarized light, texture analysis, gas chromatography with flame ionization, and mass spectrometric detection. Ultrasonic treatment affected the crystallization of oleogels and led to the formation of smaller crystals. At the same time, sonication led to both an increase and a decrease in the firmness of oleogels, depending on the composition of the gelator. As regards volatile compounds, a total of 121 fragrant substances were identified in all samples, including such groups as alkanes, alkenes, alkadienes, alkynes, alkadiynes, alcohols, ketones, aldehydes, terpenes, alkyl alkane, and alkyl benzene derivatives. Ultrasonic treatment caused formation of new volatile unsaturated compounds. Some of them are known to have an unpleasant odor and thus might be responsible for the extraneous odor formation in studied fatty systems. Those were mainly (E)-2-octene, 1-heptene, 1,3-butadiene, and 1,3-octadiene in all oleogel samples. Sonicated samples B and C additionally had but-1-en-3-yne, pentenyne, and 1,3-butadiyne, whose odor can also be characterized as extraneous and distasteful. Several volatile compounds, supposed to be products of lipid oxidation, were also identified. Here we assume a reasonable approach is needed when selecting sonication conditions to prevent undesirable taste and flavor in oleogels and oleogel-based food products.

Structural and Physical Characteristics of Mixed-Component Oleogels: Natural Wax and Monoglyceride Interactions in Different Edible Oils

Waxes and monoglycerides (MGs) added in edible oils form oleogels that can be used as an alternative structured fat, providing healthier substitutes to saturated and trans fats in foods. This study aimed to investigate the properties of oleogels formed by the interaction between monoglycerides and different waxes in various edible oils. For this purpose, waxes, namely rice bran (RBW), candelilla (CDW), sunflower (SW), and beeswax (BW), together with MGs in a total concentration level of 15% (w/w) were dissolved in several edible oils (olive, sunflower, sesame, and soybean). The structure and physical properties of oleogels were investigated using texture analysis, polarized light microscopy, melting point measurements, and Fourier-transform infrared spectroscopy (FTIR). The hardest structure was produced by SW/MG (5.18 N), followed by CDW (2.87 N), RBW (2.34 N), BW (2.24 N) and plain MG (1.92 N). Furthermore, RBW and SW led to a higher melting point (69.2 and 67.3 °C) than the plain MG oleogels (64.5 °C). Different crystallization structures, i.e., needle-like crystals and spherulites, were observed depending on the type of wax, its concentration, and the oil used. These results can be used to control the properties of oleogels by adjusting the gelator composition for a variety of potential food applications.

Food-Grade Oleogels: Trends in Analysis, Characterization, and Applicability

Currently, a large number of scientific articles can be found in the research literature in the field focusing on the use of oleogels for food formulation to improve their nutritional properties. The present review focuses on the most representative food-grade oleogels, highlighting current trends in terms of the most suitable methods of analysis and characterization, as well as trends in their application as substitutes for saturated and trans fats in foods. For this purpose, the physicochemical properties, structure, and composition of some oleogelators are primarily discussed, along with the adequacy of oleogel incorporation for use in edible products. Analysis and characterization of oleogels by different methods are important in the formulation of innovative foods, and therefore, this review discusses the most recent published results regarding their microstructure, rheological and textural properties, and oxidative stability. Last but not least, issues related to the sensory properties of oleogel-based foods are discussed, highlighting also the consumer acceptability of some of them.

Comparative study of natural wax-based W/O emulsion gels: Microstructure and macroscopic properties

In this paper, six kinds of natural wax, including sunflower wax (SFX), rice bran wax (RBX), carnauba Brazilian wax (CBX), beeswax (BWX), candelilla wax (CDX), and sugarcane wax (SGX) were used to prepare water-in-oil (W/O) emulsion gels. Microstructures and rheological properties of all emulsion gels were investigated by microscopy, confocal laser scanning microscope (CLSM), scanning electron microscopy (SEM), and rheometer, respectively. By comparing polarized light images of wax-based emulsion gels and corresponding wax-based oleogels, it could be found that dispersed water droplets greatly affected the crystal distribution and hindered crystal growth. Polarized light microscopy and CLSM images proved that natural wax could perform a dual-stabilization mechanism by interfacial crystallization and crystal networks. SEM images illustrated all waxes except SGX were platelets and formed networks by stacking on top of each other, while flocs-like SGX was easier to adsorb on the interface and formed a "crystalline shell". The surface area and pore formed by different wax varied wildly, which accounted for their differences in the gelation ability, oil binding capacity, and strength of the crystal network. The rheological study showed that all wax had solid-like properties and wax-based oleogels with denser crystal networks correspond to emulsion gels with higher modules. The dense crystal network and interfacial crystallization could improve the stability of W/O emulsion gels proved by recovery rates and critical strain. All the above proved that natural wax-based emulsion gels can be used as stable, low-fat, and thermal-sensitive fat mimics.