Structural and mechanical behavior of colloidal fat crystal networks of fully hydrogenated lauric acid-rich fats and rapeseed oils mixtures

Formation and In Vitro Simulated Digestion Study of Gelatinized Korean Pine Seed Oil Encapsulated with Calcified Wax

Natural waxes have demonstrated exceptional potential as oil gels for saturated and trans fatty acids, but their application has been limited by issues such as temperature sensitivity, lack of stability and durability, and compatibility. In this study, three types of wax (Beeswax (BW), Rice bran wax (RBW), and Carnauba wax (CW)) were combined with calcium hydroxide to produce calcified wax. The calcified Korean pine seed oil gel obtained by heating and stirring with Korean pine seed oil is responsive to temperature and has environmental adaptability. The effects of critical gel concentration, temperature regulation, texture properties, microstructure, oil-holding capacity, and FT-IR on the quality parameters of oil gel were investigated. Additionally, an in vitro digestion model was developed to comprehend the decomposition rate of fat during gel structure digestion and transportation. The results demonstrated a close correlation between the critical gelation concentration and calcium ion content. Furthermore, after calcification, the hardness followed the order BW > CW > RBW. Moreover, there was an approximate 10 °C increase in wax melting point. Conversely, BW:Ca exhibited the lowest oil leakage. The microstructures revealed that the oil gels formed post-wax calcification exhibited similar fractal dimension (Db) values (<7 μm), and the intermolecular forces were characterized by van der Waals forces, which were consistent with those observed in the non-calcified group. In conjunction with the vitro digestion simulation, our findings demonstrated that RBW and CW oil gels gradually released 20%, 35%, and 35% of free fatty acids (FFA) within the initial 30 min of intestinal digestion. Importantly, the FFA release rate was significantly attenuated, thereby providing a foundation for developing wax-based gel processed foods that facilitate gentle energy release benefits for healthy weight management.

Crystallization and Structural Properties of Oleogel-Based Margarine

Interest in oleogel as a promising alternative to traditional hydrogenated vegetable oil has increasingly grown in recent years due to its low content of saturated fatty acids and zero trans fatty acids. This study aimed to develop wax-based margarine to replace traditional commercial margarine. The wax-based margarine was prepared and compared with commercial margarine in texture, rheology, and microscopic morphology. The possibility of preparing margarine at room temperature (non-quenched) was also explored. The results showed that the hardness of oleogel-based margarine increased as the BW concentration increased. Denser droplets and crystal network structure were observed with the increase in BW content. XRD patterns of oleogel-based margarine with different content BW were quite similar and structurally to the β' form. However, the melting temperature of oleogel-based margarine was over 40 °C at each concentration, which represented a poor mouth-melting characteristic. In addition, the unique, improved physical properties of oleogel-based margarine were obtained with binary mixtures of China lacquer wax (ZLW) and Beeswax (BW), due to the interaction of the ZLW and BW crystal network. The rapid cooling process improved the spreadability of oleogel-based margarine. The margarine prepared by 5% BW50:ZLW50 had similar properties to commercial margarine in texture and melting characteristics (37 °C), which had the potential to replace commercial margarine.

Crystal network structure and stability of beeswax-based oleogels with different polyunsaturated fatty acid oils

The effect of different types of oils including camellia oil (CLO), sunflower oil (SFO), corn oil (CO) and linseed oil (LO) on the formation, crystal network structure and mechanical properties of 4%wt beeswax (BW) in oleogel was investigated. BW oleogels containing oils with higher contents of polyunsaturated fatty acids gelled first (1%wt), especially LO with higher contents of linolenic acid rather than CLO with higher contents of monounsaturated fatty acids. In comparison, oils with higher polyunsaturated fatty acid contents exhibited higher D_b with more extensive microstructure at different cooling rates, which was related to shorter nucleation induction time of crystal and higher crystallinity. Stronger van der Waals forces were observed in oleogels with higher polyunsaturated fatty acid contents especially for LO oleogel. Rheology also showed that LO oleogel with higher content of linolenic acid had higher crystallinity and lower crystal melting interfacial tension, resulting in the formation of a more stable network structure.

Crystallization behavior and nano-micro structure of lauric acid-rich fats with and without indigenous diglycerides

Crystallization behavior and nano-micro structure of lauric acid-rich fats were investigated in the absence and presence of corresponding diglycerides (DAGs) with a concentration of 2%. Results showed that the melting point and onset crystallization temperature of fats with DAGs were promoted due to the interaction of DAGs with triglycerides (TAGs). Crystallization kinetics found that the addition of DAGs shortened the fat nucleation time, and slowed down the crystal growth rate. Based on X-ray diffraction results, adding DAGs led to the decrease of the thickness of the crystalline domain and alteration of crystallization pattern. Synchrotron radiation small-angle X-ray scattering measurement further revealed the existence of fat crystal nanoplatelets with a rough surface in all the lauric acid-rich fats. However, larger structures of crystalline nanoplatelets appeared in the fats with 2% DAGs. Furthermore, denser and uniform microstructure networks appeared with more tiny crystals and higher fractal dimensions after the addition of DAGs.

Effects of Low-melting-point Fractions of Cocoa Butter on Rice Bran Wax-corn Oil Mixtures: Thermal, Crystallization and Rheological Properties

The fatty acid compositions, polymorphism, solid fat content (SFC), thermal properties, microstructure and rheological properties of fat blends of rice bran wax and corn oil (RWC) with low-melting-point fractions of cocoa butter (LFCB) in the range of 20-50% were investigated. With the raising content of LFCB, the hardness, SFC, storage modulus (G') and loss modulus (G'') of blend samples increased. The unsaturated fatty acids of blend samples with different LFCB proportion were in the range of 60.42% to 71.25%. Two kinds of polymorphism were observed in blend samples, which were β'-Form and β-Form. During the crystallization process, the rice bran wax was first crystallized, and then induced a part of LFCB formed β'-Form crystals and another LFCB formed the β-Form crystals. The results show that the addition of LFCB could improve the plasticity of fat blends and reduce the difference in properties between them and commercial shortening.

Effect of Sucrose Esterified Fatty Acid Moieties on the Crystal Nanostructure and Physical Properties of Water-in-oil Palm-based Fat Blends

The effects of sucrose ester of fatty acid (SEF) on the nanostructure and the physical properties of water-in-oil (W/O)-type emulsified semisolid fats were investigated. Model emulsions including palm-based semisolid fats and fully hydrogenated rapeseed oils with 0.5% SEF or fractionated lecithin, were prepared by rapidly cooling crystallization using 0.5% monoacylglycerol as an emulsifier. The SEFs used in this study were functionalized with various fatty acids, namely, lauric, palmitic, stearic, oleic, and erucic acids. Cryogenic transmission electron microscopy (cryo-TEM) was used to observe the sizes of the solvent- extracted nanoplatelets. The solid fat content (SFC), oil migration value, and storage elastic modulus were also determined. The average crystal size, which was measured in length, of the fat blends with SEFs containing saturated fatty acids (namely, palmitic and stearic acids) was smaller than that of the SEFs containing unsaturated fatty acids (namely, oleic and erucic acids). The effects exerted by these fatty acid moieties on the spherulite size in the corresponding bulk fat blends were observed via polarized microscopy (PLM). The results suggest that nanostructure formation upon the addition of SEF ultimately influenced these aggregated microstructures. Generally, smaller platelets resulted in higher SFC in the fat phase, and a high correlation between the SFC and the G' values in W/O emulsion fats was observed (R² = 0.884) at 30°C. In contrast, the correlation was low at 10℃. Furthermore, samples with larger nanocrystals had a higher propensity for oil migration. Thus, the addition of SEF regulated the fat crystal nanostructure during nucleation and crystal growth, which could ultimately influence the physical properties of commercially manufactured fat products such as margarine.

Characterisation of thermal and structural behaviour of lipid blends composed of fish oil and milkfat

The blend of fish oil with a high percentage of long chain poly-unsaturated fatty acids, and milkfat with a high percentage of saturated fatty acids, could potentially demonstrate desirable characteristics from both components, such as increased omega-3 fatty acids and melting point, as well as improved crystallization and oxidative stability. In this study, the effect of various milkfat concentrations on thermal properties and crystalline structure of these blends were analysed to understand parameters determining the overall characteristics of the blend. Blends with different ratios of fish oil: milkfat (9:1, 7:3, 5:5, 3:7, 1:9), as well as pure fish oil and pure milkfat, were investigated at different cooling conditions. The crystallization behaviour in all samples shifted to lower temperature ranges, by increasing the cooling rate from 1 to 32 °C/min. However, the changes in cooling rate did not have significant effect on the melting profile of the samples. Whereas changes in milkfat ratio affect both the crystallization and melting behaviour. New crystallization peaks were observed on DSC spectra between the range of -4 to -13 °C in the blends. Moreover, new melting peaks appeared in two ranges of -1 to -8 °C and 8-9 °C, in the blends. The crystallization and melting behaviour of the blends were similar to those of milkfat when >30% milkfat was used. This was further confirmed via XRD where milkfat demonstrated the dominant polymorphic behaviour. Regarding shape of the crystals, fractal dimension analysis showed a similarity between clusters in blends containing 50% milkfat or higher. Increasing the ratio of milkfat led to an increase in fractal dimension which indicates higher mass-spatial distribution of the crystal networks in the blends. The data showed that adding 30% or more milkfat to pure fish oil resulted in blends demonstrating similar characteristics to milkfat, including thermal, structural, and oxidative stability. This shows the potential of blending a high percentage of docosahexaenoic acid in milk fat to improve their overall stability.

Comparation of micro-viscosity of liquid oil in different colloidal fat crystal networks using molecular rotors

Micro-viscosity is an important parameter to describe the microenvironment of the fat crystal network. In this study, we evaluated the micro-viscosity of the liquid oil confined in mixtures of palm kernel stearin (PKS)/soybean oil (SO) and fully hydrogenated rapeseed oil (FHRSO)/SO using molecular rotors. The micro-viscosity was shown to increase with solid fat content (SFC), as well as with high proportion of triglycerides that crystallized and formed stronger linked networks. In addition, the thickness of nanocrystals decreased with the increase of solid fat and denser fat crystal network appeared with larger box-counting fractal dimension. Mathematic fit analysis further indicated that molecular confinement of the oil was strongly dependent on the microstructure with high-space filling colloidal fat crystal networks. Larger box-counting fractal dimension led to higher micro-viscosity. However, the critical box-counting fractal dimension was found to be 1.86 irrespective of the nature of the network.