Crystallization, microstructure and polymorphic properties of soybean oil organogels in a hybrid structuring system.

Organogels are semi-solid systems where the liquid phase is immobilized for three-dimensional network self-sustained formed by structuring agents capable to hold a larger quantity of liquid oil. The use of these structuring agents or crystallization modifiers, as specific triacylglycerols, emulsifiers and high molecular weight - high melting point lipids, have been recognized as the main alternative for obtaining low saturated fats for food formulation. The aim of this work was to evaluate the crystallization, microstructure and polymorphism properties of hybrid soybean oil (SO) organogels, formulated with 6% (w:w) of structuring agents through a centroid simplex system added singly, in binary or ternary association of candelilla wax (CW), sorbitan monostearate (SMS) and fully hydrogenated palm oil (FHPO). The thermal behavior, crystallization kinetics, physical stability by temperature cyclization, microstructure and polymorphism were evaluated. FHPO and CW increased the stability and ability to form crystalline networks in organogels, while SMS accelerated the crystallization process. The structuring agents increased the initial and final crystallization temperatures, even as the melting temperatures and the enthalpy values of organogels. Time-temperature cyclization (cyclization 1: 5 °C/48 h + 35 °C/24 h + 5 °C/24 h; cyclization 2: 35 °C/48 h + 5 °C/72 h) showed that all the systems resulted in firm and stable organogels, except when SMS or FHPO were used singly. CW promoted formation of denser crystalline networks with higher solids content, quick crystallization onset and higher melting points that indicates adequate thermal resistance; while FHPO increased the solid content although it was effective to obtain organogels only at the cooling temperature (5 °C). The binary interaction of FHPO + CW increased the thermal resistance of organogels; and the interactions among SMS + CW and SMS + CW + FHPO although it was effective to obtain organogels. Regardless of the presence and proportions of structuring agents, organogels were characterized by beta polymorphism.

Production and characterization of promising ß-stable seed crystals to modulate the crystallization of fat-based industrial products.

Spray cooling or spray chilling is a technique for obtaining solid lipid microparticles (SLMs) within the diameter range in micrometers using low temperatures and no organic solvents. It is a low-cost technique and is easy to scale-up. The production of SLMs into ß-form represents a technological challenge due to the fast crystallization given by the spray cooling system, which generally results in SLMs crystallized into the metastable polymorphic form α. This study focuses on the production and characterization of SLMs by spray cooling using hard fat soybean oil (HS) added of D-limonene or canola oil, aiming to their application as ß-seed crystals into lipid systems. The ß-seed crystals could turn into an alternative lipid material to be used in fat-based products that present the preferential ß' crystallization, like palm oil, increasing its compatibility with cocoa butter (CB) and allowing for the development of substitutes. The obtained SLMs showed spherical geometry and no agglomeration during storage at 25 °C for up to 30 days, verified by scanning electron microscopy (SEM). The mean diameters (D50) were between 150 and 200 µm and the ß' and ß-form, determined by X-ray diffraction (XRD), appeared immediately after the crystallization process by spray cooling using HS added of 5% D-limonene (the HS control sample presented only the α-form). The SLMs of this study demonstrated their potential use as ß-seed crystals into lipid systems.

Nanostructured lipid carriers loaded with free phytosterols for food applications.

The objective of this study was to develop nanostructured lipid carriers (NLCs) with free phytosterols (FP) using conventional fats and oils. Lipid matrices (LMs) and NLCs were produced with high oleic sunflower oil, fully hydrogenated canola (CA) and crambe (CR) oils by high-pressure homogenization (HPH). The NLCs were evaluated for hydrodynamic diameter (Z-ave), polydispersity index (PDI), and zeta potential (ZP). The melting behavior and polymorphism were investigated for both, the LMs and NLCs. The NLCs presented particle sizes ranging from 148.23 to 342.10 nm, PDI from 0.275 to 0.481, and ZP between -22.27 and -29.70 mV. The NLCs presented higher thermal resistance than that of the LMs. The use of CA and CR separately in the NLC formulations favored the incorporation of FP. The LMs and NLCs presented crystals in ß-form and in mixtures of ß' and ß forms. The developed NLCs can be used for food enrichment, such as spreads, margarine, and beverages.