Formation and Microstructures of Whipped Oils Composed of Vegetable Oils and High-Melting Fat Crystals

This paper reports the experimental results of processes used for the formation of whipped oils composed of vegetable oils (salad oil) and high‐melting fat crystals fully hydrogenated rapeseed oil rich in behenic acid (FHR‐B)]. No emulsifier was added to form this whipped oil. Microprobe FT‐IR spectroscopy, synchrotron radiation microbeam X‐ray diffraction (SR‐μ‐XRD), polarized optical microscopy, and differential scanning calorimetry (DSC) were employed to observe fine fat crystal particles of the most stable polymorph of β (β‐fat crystal), FHR‐B, and their adsorption at the air–oil surface before, during, and after the formation of the whipped oil. The results obtained revealed the following: (1) The preparation of an organogel composed of salad oil and small fibrous β‐fat crystals using a special tempering procedure was a prerequisite for forming whipped oil. (2) The β‐fat crystals were adsorbed at the air–oil surface to encapsulate the air bubbles during the formation process of whipped oil. (3) The values of overrun of the whipped oil reached >200 % after an aeration time of 30 min at 20 °C. (4) The SR‐μ‐XRD experiments demonstrated that the lamellar planes of the β‐fat crystals near the air–oil surface were arranged almost parallel to the air–oil surface plane. The present study provides the first evidence that tiny fat crystal particles may cause aeration in liquid oils without the addition of other whip‐assisting substances such as emulsifier crystals.