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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.

Sucrose esters (SE) have been investigated as structuring agents in oleogels. Due to the low structuration power of SE as single agent, this component has recently been explored in combination with other oleogelators to form multicomponent systems. This study aimed to evaluate binary blends of SEs with different hydrophilic-lipophilic balances (HLBs) with lecithin (LE), monoglycerides (MGs) and hard-fat (HF), according to their physical properties. The following SEs, SP10-HLB2, SP30-HLB6, SP50-HLB11, and SP70-HLB15, were structured using three different routes: "traditional", "ethanol" and "foam-template". All binary blends were made using a 10% oleogelator in 1:1 proportion for binary mixtures; they were then evaluated for their microstructure, melting behavior, mechanical properties, polymorphism and oil-binding capacity. SP10 and SP30 did not form well-structure and self-standing oleogels in any combination. Although SP50 showed some potential blends with HF and MG, their combination with SP70 led to even more well-structured oleogels, with a higher hardness (~0.8 N) and viscoelasticity (160 kPa), and 100% oil-binding capacity. This positive result might be attributed to the reinforcement of the H-bond between the foam and the oil by MG and HF.

Sucrose esters (SE) have been widely studied as emulsifiers to tailor crystallization in fats. Nevertheless, few studies have assessed the potential of SEs as oleogelators to structure oleogels. This study aimed to evaluate alternative routes that would improve the oleogelation capacity of commercial SEs with different Hydrophilic-lipophilic balance (HLB) values and evaluate the physical properties of the oleogels produced by different routes. Four SEs were evaluated (SP10-HLB2, SP30-HLB6, SP50-HLB11, and SP70-HLB15) using three oleogelation routes (traditional or melting, ethanol, and foam-template). Of all evaluated samples, only the SP50 ethanol route with 10 % SE showed a solid-like structure. This sample presented the highest hardness (0.4 ± 0.1 N) and elastic modulus (4589 ± 89 Pa). SP70 showed a potential oleogel after foam-template approach due to the higher oil binding capacity. SP10 was the only directly completely soluble SE in oil, although it formed a very liquid gel. SP30 did not show a potential or oleogel structure for any of the routes tested., Competing Interests: 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., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Fats and oils in food give them flavor and texture while promoting satiety. Despite the recommendation to consume predominantly unsaturated lipid sources, its liquid behavior at room temperature makes many industrial applications impossible. Oleogel is a relatively new technology applied as a total or partial replacement for conventional fats directly related to cardiovascular diseases (CVD) and inflammatory processes. Some of the complications in developing oleogels for the food industry are finding structuring agents Generally Recognized as Safe (GRAS), viable economically, and that do not compromise the oleogel palatability; thus, many studies have shown the different possibilities of applications of oleogel in food products. This review presents applied oleogels in foods and recent proposals to circumvent some disadvantages, as reaching consumer demand for healthier products using an easy-to-use and low-cost material can be intriguing for the food industry.

The use of multicomponent oleogels combined with a physical process such as high-intensity ultrasound (HIU) has become an interesting alternative to overcome nutritional and technological issues in fat-based foods. This is because the combination can add technological properties without changing the total amount of gelators, improving sensory acceptance and clean label claim. In this context, the study aims to evaluate the structuration power and physical properties of oleogels formed by monoglycerides (MG), fully hydrogenated rapessed oil (FHRO), and lecithin (LE) in rapeseed oil, with and without HIU. All samples were analyzed according to their microstructure, melting behavior, rheology, texture, polymorphism, and oil binding capacity. In mono-structured oleogels, only MG was able to form gels that did not flow. Three synergic combinations that produced 99% oil binding capacity oleogels were found: MG: FHRO, FHRO:LE, and MG:FHRO:LE. These combinations showed improved physical properties like hardness, elastic modulus, and oil loss when sonicated, which was attributed to the induced secondary crystallization of the FHRO promoted by HIU., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This paper addresses sorbitan and sucrose ester in physical transformations of palm mid-fraction (PMF). Both emulsifiers influenced the crystallization properties of PMF, mainly due to emulsifier solubility, which affects its ability to interfere with the kinetics of solution-mediated phase transformations. DSC results corroborate the polymorphism analysis, indicating that the mechanism and rate of phase transformation depend on the chemical structure and amount of each emulsifier. The addition of sorbitan tristearate (STS) and sucrose stearate (S-370) increased the crystallization speed of the PMF and caused changes in the crystallization behavior. STS favored the β'→β transition, while S-370 stabilized the β'-form. We can conclude that the presence of emulsifiers dissimilar to the composition of PMF modified its physical structure, either by increasing the liquid fraction or by reducing molecular motion, facilitating or preventing polymorphic transformations., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

High-intensity ultrasound (HIU) has been used in the past to change fat crystallization and physical properties of fat crystalline networks. The objective of this work was to evaluate how HIU placed on different positions in a scraped surface heat exchanger (SSHE) using different processing conditions affect the physical properties of an interesterified palm olein. The sample was crystallized at two temperatures (20 °C and 25 °C) and two agitation rates (344/208 rpm and 185/71 rpm, barrels/pin worker). HIU (12.7 mm-diameter tip, 50% amplitude, 5 s pulses) was placed at three different positions within the SSHE. After processing, samples were stored at 25 °C for 48 h and analyzed according to the crystal morphology, solid fat content (SFC), oil binding capacity (OBC), melting behavior, viscoelasticity, and hardness. Physical properties were affected by crystallization conditions, by sonication, and by HIU position. The greatest improvement obtained was at 20 °C using low agitation when HIU was placed at the beginning of the SSHE. These conditions result in a sample with 98.9% of OBC, 274 kPa of viscoelasticity and 31 N of hardness. These results show that HIU can be used as an additional processing tool to improve physical properties of a palm-based fat and that the best improvement was obtained as a combination of crystallization conditions and HIU position., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Oleogels and oleogelation routes have been extensively studied in the past decade; however, the industry has not yet implemented this technique due to price, availability, and clean label. The objective of this study was to evaluate the synergism of binary oleogels structured by monoglycerides (MG) and high melting point triacylglycerols (HF) with and without high-intensity ultrasound (HIU) according to their physical properties. MG:HF (0:6, 1:5, 2:4, 3:3, 4:2, 5:1, and 6:0) oleogels were produced by mixing at 70 °C with a stirring of 350 rpm for 5 min, followed by a cooling and storage at 20 °C for 24 hr. A 20-kHz HIU was applied for 10s, 30s, or 10s using three pulses (10sON/10sOFF) during the cooling step via a macro tip (12.7 mm) and 50% amplitude (56 W) in the presence of few -crystals. Samples were evaluated according to their hardness, oil-binding capacity (OBC), microstructure, melting behavior, viscoelasticity, and flow behavior. The best physical properties were found in the MG6:HF0 oleogel, with a hardness of 1.2 N, elasticity of 5.5 kPa, viscosity of 99 Pa⋅s and 99% OBC. These properties were reduced with the decrease of MG in the blend. The sonication did not improve the MG6:HF0, instead it affected its properties negatively. However, sonication showed a positive effect on the blends of MG and HF. The hardness was improved at least threefold and OBC around 20%, these effects were already observed using only 10s sonication. Sonocrystallization induced secondary nucleation and changed the crystalline material only in blends containing HF indicating the better effect of the sonocrystallization on oleogels in the presence of high-melting points triacylglycerols. PRACTICAL APPLICATION: Oleogels are a valuable alternative in food industry to replace trans and reduce saturated fatty acids content in many food products. The combination of a binary structuration and use of high-intensity ultrasound that is a physical green technology will give the food industry information on how to improve the physical properties of oleogels without increasing the amount of oleogelators, giving a future alternative to clean label and sensory claims of oleogels applications., (© 2021 Institute of Food Technologists®.)

The objective of this work was to evaluate the effect that agitation rate, crystallization temperature, and sonication have on the physical properties of a soybean-based fat with low levels of saturated fatty acids crystallized in a scraped surface heat exchanger (SSHE). The sample was crystallized at two temperatures (20 and 25 °C) and agitation rates (344/208 rpm in the barrels/pin worker-high agitation HA and 185/71 rpm barrels/pin worker-low agitation LA), and a constant flow of 11 L/hr. High-intensity ultrasound (HIU - 12.7 mm-diameter tip, 50% amplitude, 5 s pulses) was coupled to a water jacketed flow-cell and placed at three different positions within the SSHE. The combination of all those parameters affected samples' physical properties. Higher oil binding capacity (OBC) and elasticity (G') were obtained at 20 °C compared to 25 °C (77% vs. 63.78% for OBC and 30.4 kPa vs. 6 kPa for G', respectively) due to the smaller crystals formed at 20 °C. Fewer or no differences were observed due to agitation alone, but LA conditions allowed for more secondary nucleation to form due to sonication and resulted in a higher improvement on the properties of the fat. PRACTICAL APPLICATION: Fat crystallization in a scrapped surface heat exchanger (SSHE) combined with a high-intensity ultrasound (HIU) gives a realistic idea of how the HIU would work in an industrial line under continuous flow, shaved shear, and different supercooling. Results from this research will provide industry with tools on how and where to incorporate HIU in their processing line. Moreover, will give information on how to combined crystallization conditions and sonocrystallization in order to obtain improved physical properties., (© 2020 Institute of Food Technologists®.)

Oil migration (OM) has been an immense issue in fat-based foods such as peanut butter and chocolate fillings. The objective of this study was to evaluate the effect of high-intensity ultrasound (HIU) on OM in a palm kernel oil-based fat used in chocolate fillings, coatings, and confectionery applications. The sample was crystallized at 30 °C for 90 min and stored for 48 hr at 25 °C. HIU was applied after 20 min at 30 °C using a 3.2-mm diameter tip operating at an amplitude of 216 µm (90 W) for 10 s. OM was measured using a centrifuge- and a filter paper-based method. Crystal morphology and size, solid fat content (SFC), melting behavior, and hardness were evaluated after 90 min, 48 hr, and after OM. Results showed that HIU reduced OM (P < 0.05) by 52.0% when measured using the filter paper method while a reduction of 97.4% was observed when measured with the centrifuge method. HIU also reduced the crystal size (P < 0.05) and formed a more organized crystalline network. A reduction in peak temperature (T p ) after 90 min of crystallization and 48 hr of storage was observed in sonicated samples without affecting the enthalpy. However, enthalpy and T p were higher in the sample without HIU analyzed after OM due to the migration of low melting point triacylglycerols out of the crystalline network. HIU also increased the hardness (P < 0.05) from 1.37 N and 3.17 N. But no differences (P > 0.05) were found on SFC due to sonication. Overall, HIU changed the crystalline structure of the fat allowing for a better entrapment of liquid oil in the crystalline matrix. Results from this study will benefit food producers that are looking for fat sources with better capacity to entrap oil. PRACTICAL APPLICATION: OM is one of the main problems facing the fat industry, especially since the elimination of partially hydrogenated fats from foods. Efforts are being focused on finding new technologies to reduce OM and therefore to improve the shelf life of the product. This study introduces for the first time, a new processing technology to reduce OM in a palm kernel fat with high content of saturated fatty acids that is commonly used in confectionery applications., (© 2020 Institute of Food Technologists®.)

Fully hydrogenated oils or hardfats are low cost and highly available products used in lipid technology while candelilla wax (CLX) is a well-known oleogelator that has been thoroughly studied over the last decade. CLX is capable of making a strong oleogel when used in very low concentrations (~1.5%) while hardfats need to be added in higher concentrations (>10%) to form a gel. Based on the molecular similarity between hardfats and CLX the aim of this work is to evaluate the use of CLX and various hardfats in combination to form stable oleogels. The hardfats used in this study in combination with CLX were crambe (HCr), palm (HPl), palm kernel (HPk) and soybean (HSb). The total concentration of oleogelator used was 5% and soybean oil was used as the dispersing media. The proportions of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 of CLX:hardfats were studied. HPl and HCr fats formed a more stable and organized crystal network when used in all blends as shown by a shift towards to lower melting temperatures. However, G' and oil loss were close to CLX only when HPl was added in small amounts (0.25 and 0.5). The HSb fat presented similarity to CLX only for blend 0.25. HPk did not show any interaction with CLX due to the different triacylglycerol composition of this hardfat compared to the others. These results show that hardfats have the potential to be used in oleogel formulation especially when used in combination with CLX. The use of hardfats is attractive to producers since they are inexpensive and readily available and they can be used to reduce the total amount of CLX in food formulations avoiding the common waxy sensation associated with CLX formulations., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The characterization of fat components becomes very useful for formulation of shortening, margarines and fat products due to their unique properties of plasticity, texture, solubility, and aeration. However, X-ray diffraction experiments on such materials are usually limited to a qualitative evaluation of the polymorphic properties based only on the characteristic d-spacing peak intensities. In this work, interesting results based on the Rietveld Method have supported both a Quantitative Phase Analysis and Degree of Crystallinity study on industrial and academic appealing samples, such as triacylglycerol standards, fully hydrogenated vegetable oils (hardfats) and cocoa butter. This useful approach to the area of oils and fats can provide valuable information about the polymorphism and its relationship to the application of lipid materials in food science and technology. Here, the discrimination between β and β' polymorphs on samples made of mixtures or blended hardfats was attained, and the results have shown a relevant contrast in comparison to a purely qualitative approach. Assessment of amorphous content on cocoa butter samples was achieved by isolating its contribution from the total X-ray diffraction background via mathematical tools during the whole pattern fitting., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Cocoa butter (CB) provides unique crystallization characteristics to chocolates and confectionary products; hence, it is an important value-add product. However, other alternative fats that minimally affect the crystallization behaviour of chocolates and confectionary products are now being increasingly used. This study analyzed the crystallization behaviour of CB, cocoa butter substitutes (CBSs), and their blends. Blends were prepared using CBS concentrations: 5, 10, 15, 20 and 37.5%. CB, CBS, and their blends were evaluated by following analysis: solid fat content, isothermal analysis, polarized light microscopic, thermal behaviour, X-ray diffraction and consistency. Crystallization analysis showed an incompatibility between the 2 fats, with a reduction in the crystallinity and increase in liquid content in all the blends. Eutectic crystallization at 20 °C was only observed for the blend containing 20% CBSs. This was considered as a positive result because previous studies have indicated that CBS concentration in CB blends should not be more than 5%.