Liquid to Semisolid Rheological Transitions of Normal and High‐oleic Peanut Oils upon Cooling to Refrigeration Temperatures

Rheological transitions of peanut oils cooled from 20 to 3 °C at 0.5 °C/min were monitored via small strain oscillatory measurements at 0.1 Hz and 1 Pa. Oils were from nine different cultivars of peanut, and three oils were classified as high‐oleic (approximately 80% oleic acid). High‐oleic oils maintained an overall liquid‐like character at 3 °C for 2 h. In contrast, several normal (non high‐oleic) peanut oils displayed a predominantly elastic (solid‐like) response after 2 h at 3 °C. Increases in viscoelasticity were associated with lipid crystallization events as confirmed by DSC. The higher ( p < 0.001) liquid viscosities and increased ( p < 0.001) contents of oleic acid, which has a more non‐linear structure as compared to other fatty acids typical in these oils, were hypothesized to hinder crystallization in high‐oleic oils. Changes in viscoelasticity at 3 °C were greatest for three normal oils that had the significantly ( p < 0.001) highest content of C20:0 and/or C22:0 fatty acids, and these long, saturated hydrocarbon chains are hypothesized to promote crystallization. No peanut oil maintained clarity after 5.5 h at 0 °C (modified cold test used to screen salad oils); however, these data as a whole suggest strategies for breeding and/or processing peanut oils for enhanced resistance to crystallization.