Crystallisation of palm olein under the influence of sucrose esters

From Nucleation to Fat Crystal Network: Effects of Stearic-Palmitic Sucrose Ester on Static Crystallization of Palm Oil

Palm oil (PO), a semi-solid fat at room temperature, is a popular food ingredient. To steer the fat functionality, sucrose esters (SEs) are often used as food additives. Many SEs exist, varying in their hydrophilic-to-lipophilic balance (HLB), making them suitable for various food and non-food applications. In this study, a stearic-palmitic sucrose ester with a moderate HLB (6) was studied. It was found that the SE exhibited a complex thermal behavior consistent with smectic liquid crystals (type A). Small-angle X-ray scattering revealed that the mono- and poly-esters of the SE have different packings, more specifically, double and single chain-length packing. The polymorphism encountered upon crystallization was repeatable during successive heating and cooling cycles. After studying the pure SE, it was added to palm oil, and the crystallization behavior of the mixture was compared to that of pure palm oil. The crystallization conditions were varied by applying cooling at 20 °C/min (fast) and 1 °C/min (slow) to 0 °C, 20 °C or 25 °C. The samples were followed for one hour of isothermal time. Differential scanning calorimetry (DSC) showed that nucleation and polymorphic transitions were accelerated. Wide-angle X-ray scattering (WAXS) unraveled that the α-to-β' polymorphic transition remained present upon the addition of the SE. SAXS showed that the addition of the SE at 0.5 wt% did not significantly change the double chain-length packing of palm oil, but it decreased the domain size when cooling in a fast manner. Ultra-small-angle X-ray scattering (USAXS) revealed that the addition of the SE created smaller crystal nanoplatelets (CNPs). The microstructure of the fat crystal network was visualized by means of polarized light microscopy (PLM) and cryo-scanning electron microscopy (cryo-SEM). The addition of the SE created a finer and space-filling network without the visibility of separate floc structures.

Internal Factors Affecting the Crystallization of the Lipid System: Triacylglycerol Structure, Composition, and Minor Components

The process of lipid crystallization influences the characteristics of lipid. By changing the chemical composition of the lipid system, the crystallization behavior could be controlled. This review elucidates the internal factors affecting lipid crystallization, including triacylglycerol (TAG) structure, TAG composition, and minor components. The influence of these factors on the TAG crystal polymorphic form, nanostructure, microstructure, and physical properties is discussed. The interplay of these factors collectively influences crystallization across various scales. Variations in fatty acid chain length, double bonds, and branching, along with their arrangement on the glycerol backbone, dictate molecular interactions within and between TAG molecules. High-melting-point TAG dominates crystallization, while liquid oil hinders the process but facilitates polymorphic transitions. Unique molecular interactions arise from specific TAG combinations, yielding molecular compounds with distinctive properties. Nanoscale crystallization is significantly impacted by liquid oil and minor components. The interaction between the TAG and minor components determines the influence of minor components on the crystallization process. In addition, future perspectives on better design and control of lipid crystallization are also presented.

Tracing distribution and interface behavior of water droplets in W/O emulsions with fat crystals

Sucrose palmitate (P170) and sucrose laurate (L195) were used as emulsifiers to control the crystallization behavior of AMF and to stabilize W/O emulsions. In this study, the P170 promoted crystallization and led to strong fat crystal networks with smaller AMF crystals (60-80 μm) in emulsions, retaining flocculation. Water droplets were squeezed into irregular shapes between the strong network but the P170 formed an interface layer with better strength to resist the aggregation. Contrarily, the L195 inhibited crystallization and formed larger AMF spherulites (more than 100 μm) resulting in a low strength of fat crystal networks and unstable emulsions. Meanwhile, the water droplets were easily fixed on the surface of AMF crystals because of the existence of sucrose esters. Protruding crystals on the surface of larger spherulites could pierce the water-oil interface, leading to a greater coalescence and forming larger water droplets. Therefore, a weak crystal network could not prevent the sedimentation and phase separation caused by gravity.

Balancing functional and health benefits of food products formulated with palm oil as oil sources

Palm oil (PO) is widely utilised in the food industry and consumed in large quantities by humans. Owing to its bioactive components, such as fatty acids, carotenoids, vitamin E, and phenolic compounds, PO has been utilised for generations. However, public concern about their adverse effects on human health is growing. A literature search was conducted to identify fractionated palm oil processing techniques, proof of their health advantages, and potential food applications. Refined palm oil (RPO) is made from crude palm oil (CPO) and can be fractionated into palm olein (POl) and palm stearin (PS). Fractional crystallisation, dry fractionation, and solvent fractionation are the three basic fractionation procedures used in the PO industry. The composition of triacylglycerols and fatty acids in refined and fractionated palm oil and other vegetable oils is compared to elucidate the triacylglycerols and fatty acids that may be important in product development. It is well proven that RPO, POl, and PS extends the oil's shelf life in the food business. These oils have a more significant saturated fat content and antioxidant compounds than some vegetable oils, such as olive and coconut oils, making them more stable. Palm olein and stearin are also superior shortening agents and frying mediums for baking goods and meals. Furthermore, when ingested modestly daily, palm oils, especially RPO and POl, provide health benefits such as cardioprotective, antidiabetic, anti-inflammatory, and antithrombotic effects. Opportunities exist for fractionated palm oil to become a fat substitute; however, nutrition aspects need to be considered in further developing the market.

Tailoring crystallization and physical properties of palm mid-fraction with sorbitan tristearate and sucrose stearate

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.

Delaying crystallization in single fractionated palm olein with limonene addition

Single fractionated palm olein (OL) becomes cloudy when submitted to low temperatures. To overcome this technological issue, the use of appropriate additives delays or prevents its clouding. Limonene is considered a green additive, and studies revealed that it modulates fat crystallization. This study evaluated the influence of adding R-(+)-limonene, in different concentrations (1-10%), into OL, regarding its crystallization behavior. The findings show that addition of limonene reduced solid fat content (SFC), crystallization temperature by differential scanning calorimetry (DSC), and cloud point of OL, and the results were more pronounced at higher concentrations of limonene. The blend OL + 10% limonene presented the best resistance in cold stability. From the obtained results, the blends fitted as intermediate products between an OL and a super palm olein (SOL), with substantial improvement in reducing crystals' formation in OL. Limonene can be considered a green anti-crystallizer with potential application in different areas, such as cosmetics and biodiesel.

Improved Thermal Properties and Flow Behavior of Palm Olein-Based Diacylglycerol: Impact of Sucrose Stearate Incorporation

Palm olein-based diacylglycerol (POL-DAG) oil is a healthy product that is produced through enzymatic reaction and purification processes. However, POL-DAG oil easily solidifies at room temperature and crystallizes at high temperatures. The effect of different concentrations of sucrose stearate (1 and 10 g kg−1) added as a nonionic emulsifier, to POL-DAG oil containing 800 g kg−1 diacylglycerol, on its physical properties and flow behavior were investigated. The thermal properties of POL-DAG oil in melting, crystallization transition, and onset temperature were significantly decreased (p < 0.05) with the addition of emulsifiers. Besides, the incorporation of emulsifiers also significantly reduced (p < 0.05) the hardness of POL-DAG oil. Moreover, all POL-DAG oils with emulsifiers incorporated exhibited shear-thinning behavior, a low consistency coefficient (K) and a low apparent viscosity. The present study resolves the solidification issue and eases the pourability of POL-DAG oil by the incorporation of sucrose stearate. The process of adding an emulsifier to POL-DAG oil is a simple method that does not require advanced technology or process modifications to manage the POL-DAG oil and thus is highly applicable for the fats and oils industries and palm oil refineries.

The Effect of Polyglycerol Esters of Fatty Acids on the Crystallization of Palm Olein

This research investigated the effect of polyglycerol ester of fatty acids (PGE) on the crystallization of palm olein (POL). Three PGEs were studied: two solid-state PGEs (PGE1105 and PGE1117) and one liquid-state PGE (PGE1155). The addition of 0.5-5% wt. PGEs influenced the crystallization kinetics of POL and this depended on the type and concentration of the emulsifiers. During cooling down with a cooling rate of 5℃/min, the samples containing PGE1105 and PGE1117 started to crystallize at higher temperatures when compared with POL but the crystallization began at lower temperatures for the samples containing PGE1155. All samples with added PGEs exhibited lower solid fat content than that of POL after 12 h of crystallization time. The number of crystals decreased with an increase in the crystal size with PGE addition but there was no effect on polymorphism. Overall, the results suggested that PGE1105 and PGE1117 enhanced the early stages of POL crystallization possibly via the template effects but suppressed the later stages, whereas PGE1155 delayed the whole process of POL crystallization. The application of POL is often limited by its tendency to get cloudy at low temperatures during long-term storage. Based on the results, 1-5% wt. PGE1155 could be used to delay or prevent the crystallization of POL at low temperatures.