Abstract: The aim of this study was to reveal the mechanism by which lipid crystallization regulates the stability of recombined whipped cream emulsion at room temperature. Eleven fat and oil samples, including anhydrous milk fat, palm oil and its derivatives, and lard, were divided into a high-saturation group (saturated fat content ≥ 70%) and a medium- and low-saturation group (saturated fat content < 70%) according to their saturated fatty acid contents. Multi-scale characterization techniques, such as gas chromatography (GC), differential scanning calorimetry (DSC), X-ray diffraction (XRD), pulsed nuclear magnetic resonance (pNMR), and a rheometer, were used to systematically analyze the influence of oils with varying degrees of saturation on the stability of the emulsion at room temperature. The results showed that the medium- and low-saturation group was mainly composed of palmitic acid (C16:0) and oleic acid (C18:1), and formed β’crystal forms with small size and thin thickness at room temperature. The nanosheet crystal size was about 100 nm, and the solid fat content ranged from 15% to 40%. For all fat and oil samples except palm oil (PO), the oil-water interface contact angle was between 153.1° and 163.1°, and the resulting emulsions exhibited moderate interfacial protein concentration (0.8–1.3 mg/mL) and low partial aggregation rate (< 6%) at room temperature. Rheological analysis showed that during temperature cycling and frequency sweep, the elastic modulus of the medium-and low-saturation group changed less, especially for the palm mid-fraction emulsion, where the change in elastic modulus during temperature sweep was only 1.1 Pa, and that during the frequency sweep was 28.99 Pa, which fully demonstrated its excellent emulsion stability. Correlation analysis further confirmed that the changes in elastic modulus during temperature and frequency sweep were both significantly positively correlated with the partial aggregation rate. This study provides a scientific basis and technical support for the rational design of oil crystallization, the optimization of the crystallization properties of recombined whipped cream by directional regulation of oil saturation degree, and the development of a stable recombined whipped cream with a low aggregation rate suitable for storage and transportation at room temperature.

Key words: saturation degree; lipid crystallization; emulsion stability; room temperature; recombined whipped cream