In this paper, two emulsion systems with high and low solid fat contents were prepared from 20 % water phase and 80 % oil phase by adjusting the palm oil/palm stearin/soybean oil ratio. Different ultrasonic power and time were used for the pretreatment of emulsion with different solid fat content, and the application characteristics of ultrasonic in W/O emulsions were explored and evaluated. Directly using high-intensity ultrasound to prepare fatty emulsions would weaken the hardness and storage modulus G\' of the samples. Although ultrasound reduced the size of fat crystals in emulsions, the interaction between water droplets and fat crystals needs to be considered. After ultrasonic treatment, water droplets were difficult to immobilize on the crystal surface and thus acted as an active filler to stabilize the emulsion together with the fat crystal network. In high solid fat emulsion systems, an increase in ultrasound power (from 100 W to 200 W) could more affect the crystallization behavior of fats than an increase in ultrasound duration (from 30 s to 60 s), and the distribution of crystals and droplets was more uniform. In the low solid fat emulsion system, the texture of the sample after ultrasonic treatment was softer, and the surface was more delicate and smoother. However, the higher ultrasonic intensity (200 W) was not conducive to the preparation of the spread. Although the ultrasound with excessive intensity promoted the formation of small crystals, it would also lead to the aggregation of small crystals. These small crystals cannot form a uniform crystal network, which increases the fluidity of emulsions.

The actual food system with fat is always complex and fat crystal and fat crystal networks have important effects on the physical properties of food. Recently, power ultrasound (PU) had been widely recognized as an auxiliary technology of fat crystallization to modify food properties. This review expounded on the mechanism of ultrasonic crystallization, and summarized effects of various factors in the process of ultrasonic treatment on fat crystallization. Based on the above, combined with the application of ultrasound in emulsions, the ultrasonic fat crystallization effect in the emulsion system was judged and described. Research results indicated that PU could shorten the induction time of crystallization, accelerate the formation of crystal nuclei, and change the polymorphism of fat crystals. The product treated by PU formed smaller and more uniform crystals to produce a more viscoelastic fat crystal network. In emulsion systems, ultrasonic treatments showed the same effect, but the effect of ultrasonic crystallization on the emulsion stability was different due to fat crystals in different emulsion systems. Meanwhile, the importance of ultrasonic crystallization in lipid emulsions was emphasized, thus ultrasonic crystallization had great potential in emulsion systems.

OBJECTIVE: Although lipid crystals (LCs) have received attention as a causative factor of plaque rupture, the mechanisms by which they increase plaque vulnerability are unknown. We examined whether solid-state LCs physically affect the adjacent extracellular matrix (ECM) using a combination of multimodal nonlinear optical (MNLO) imaging and finite element analysis (FEA).
METHODS: The changes of ECMs affected by lipids in atherosclerotic arteries in apolipoprotein E-deficient mice (n = 32) fed a high-fat diet for 20-30 weeks were micro-anatomically visualized by a 3D MNLO imaging platform including CARS for lipids, TPEF for elastin, and SHG for collagen.
CONCLUSIONS: The TPEF signal of elastin was increased at the peripheral regions of LCs (<10 μm) compared with foam cell regions. In order to confirm the increase of elastin, biochemical assay (western blot) was performed. The protein level of elastin was increased approximately 2.25-fold (p = 0.024) in LC-rich arteries. Under the hypothesis that the increase of elastin resulted from the mechanical stimulus from solid-state LCs, MNLO images were subjected to FEA to simulate the displacement according to the expanding magnitude of the vessel during cardiac cycles. We found that microscale focal stress was increased specifically around the LCs. These FEA results corresponded with the increase of elastin observed by TPEF. These data suggest that LCs mechanically stimulate the adjacent ECM to alter the composition of ECM and cause vessel remodeling. The combination of MNLO imaging and FEA has great potential to verify the mechanical predictions in cardiovascular diseases.