Effect of high cooling and shear rate on the microstructural development of hybrid systems containing diacylglycerols and triacylglycerols of palm origin

This research explores the potential of diacylglycerol (DAG) and triacylglycerol (TAG) combinations in shortenings. An alternative formulation of a fat blend alters the crystallization behavior, which was investigated with differential scanning calorimetry (DSC) and synchrotron X-ray diffraction. DSC experiments demonstrated that by replacing TAGs with DAGs, crystallization had an earlier onset. However, the lower concentrations of TAGs require more undercooling to fully crystallize, which resulted in more crystallization events during the isothermal step for samples with a higher DAG and lower TAG concentration. A higher DAG concentration also resulted in a more dominant presence of the beta polymorphic form. As both DAG and TAG structuring are based on crystal network formation, processing conditions (cooling and shear) will play an important role. Considering processing is essential to understand the behavior of newly formulated fats on an industrial processing line. Samples were prepared both statically, without shear or rapid cooling, and dynamically, under high shear and fast cooling using a bench-top scraped surface heat exchanger. Dynamically crystallized samples containing DAGs were more brittle than samples without DAGs, which can be related to the slower crystallization kinetics of lower TAG concentrations at higher DAG concentrations. The final textural properties of the statically crystallized samples could not predict the properties of the dynamic values. As such, it was demonstrated that preparing crystalline samples using processing conditions similar to those used in an industrial setting is essential to assess applicability of alternatively structured crystalline fat phases

Correction: Food-grade monoglyceride oil foams: the effect of tempering on foamability, foam stability and rheological properties

Foams with a continuous oil phase may be stabilized using crystalline particles. Those systems are compelling because of their potential in edible oil structuring, modifying sensorial properties and creating healthier food products. This study aimed to relate oleogel (unwhipped state) properties to oil foam (whipped state) properties using a monoglyceride-sunflower oil model system. The properties of crystal-oil mixtures were influenced by time and temperature during preparation and storage. Therefore, oleogels were prepared using different tempering protocols and their resulting microstructure was investigated with rheology, differential scanning calorimetry and X-ray diffraction. The corresponding oil foams were characterized in terms of foamability and foam stability. The properties of both systems were studied immediately after preparation as well as after 4 weeks of storage. We demonstrated that there is a large influence of the time-temperature history on the foam properties. Partially crystallized mixtures were shown to form weaker structures which capture more air because of their lower viscosity and as crystallization would preferentially take place at the interface. They were characterized by larger bubbles and were less stable and firm. It is proposed that their rheological properties are mainly dominated by interfacial contributions. Fully crystallized and stored monoglyceride-oil mixtures were seen to form stronger gel networks which included less air, contained smaller air bubbles and were stable during storage. It is hypothesized that these samples also included an important bulk gelation contribution

Food-grade monoglyceride oil foams: the effect of tempering on foamability, foam stability and rheological properties

Foams with a continuous oil phase may be stabilized using crystalline particles. Those systems are compelling because of their potential in edible oil structuring, modifying sensorial properties and creating healthier food products. This study aimed to relate oleogel (unwhipped state) properties to oil foam (whipped state) properties using a monoglyceride-sunflower oil model system. The properties of crystal–oil mixtures were influenced by time and temperature during preparation and storage. Therefore, oleogels were prepared using different tempering protocols and their resulting microstructure was investigated with rheology, differential scanning calorimetry and X-ray diffraction. The corresponding oil foams were characterized in terms of foamability and foam stability. The properties of both systems were studied immediately after preparation as well as after 4 weeks of storage. We demonstrated that there is a large influence of the time-temperature history on the foam properties. Partially crystallized mixtures were shown to form weaker structures which capture more air because of their lower viscosity and as crystallization would preferentially take place at the interface. They were characterized by larger bubbles and were less stable and firm. It is proposed that their rheological properties are mainly dominated by interfacial contributions. Fully crystallized and stored monoglyceride–oil mixtures were seen to form stronger gel networks which included less air, contained smaller air bubbles and were stable during storage. It is hypothesized that these samples also included an important bulk gelation contribution

Polymer coated fat crystals as oil structuring agents: Fabrication and oil-structuring properties

peer reviewedOleogel has attracted the interest of food scientists and the food industry as an interesting alternative for solid fat in food products. Certain hydrophilic polymers, such as gelatin (GTA), are known to form gel structures in water, but fail to structure apolar solvents due to incompatibility. The hydrophilic polymers can only be introduced into an apolar solvent using an indirect approach. In our approach, GTA acted as a stabilizer of oil-in-water emulsions. During emulsification, GTA adsorbed at the interface, forming a polymer protective layer. Upon cooling, crystallisation of fully hydrogenated rapeseed oil (FHRO), as the oil droplets, fixed the polymer layer onto the droplets. Subsequently, the crystallised fat droplets were separated from the continuous water phase through creaming, and then subjected to drying. The dried fat droplets, fat capsules, exhibited spherical shape with D(3,2) at 6.7 ± 3.3 μm based on the microscopy and laser light scattering analyses. Interestingly, confocal laser scanning microscopy (CLSM) confirmed the location of the GTA layer on the surface of the fat capsules. Moreover, diffraction and thermal analyses showed similar properties between FHRO and GTA fat capsules, thus indicating that FHRO independently crystallised without being affected by the fabrication techniques and GTA. Subsequently, the fat capsules were tested as an oil structuring agent by employing two different approaches to form composite oleogels and particle-based oleogels. The amplitude sweep test showed that all oleogels behaved in a solid-like manner. The shear modulus of oleogels prepared from fat capsules was higher than the reference oleogel, regardless of the preparation approach. Electron microscopy confirmed the formation of composite oleogel and particle-based oleogels by the fat capsules as the structuring building blocks in the respective oleogels. In the oleogels, GTA acted as a filler in GTA-oleogel (GTA1) and as a surface polymer that interconnected the fat capsules in particle-based oleogel (GTA2) and particle-based added water oleogel (GTA3). Ultimately, we have shown the formation of FHRO coated with hydrocolloid, which can potentially act as a functional material for structuration and delivery vehicles. © 2021 Elsevier Lt