Physical analyses of gel‐like behavior of binary mixtures of high‐ and low‐melting fats

Abstract

AbstractGel‐like fat mixtures of high‐melting (HM) and low‐melting (LM) fats were formed by means of rapid cooling and subsequent heating. No “non‐fat” ingredients such as emulsifiers, water, or waxes were added to the mixtures. The gel‐like fats having solid fat content (SFC) values below 2.0 wt% formed crystal networks of HM‐fats that entrapped the liquid oil fraction of LM‐fats. In a search for optimal fat combinations exhibiting gel‐like behavior, fully hydrogenated rapeseed oil with a high amount of behenic acid (FHR‐B), fully hydrogenated rapeseed oil with a high amount of stearic acid (FHR‐S), tristearoylglycerol (SSS), triarachidonoyl‐glycerol (AAA), and tribehenoylglycerol (BBB) were examined as the HM‐fats. For LM‐fats, sal fat olein (SFO), cocoa butter (CB), palm super olein (PSO), and olive oil were examined. The following results were obtained: (i) the gel‐like behavior was observed in mixtures of FHR‐B/SFO and FHR‐B/CB with initial concentrations of FHR‐B of 1.5–4.0 wt%. (ii) Rapid cooling to Tc (crystallization temperature) from 70°C and subsequent heating to Tf (final temperature) were necessary to reveal the gel‐like behavior, whereas simple cooling without a cooling/heating procedure did not form the gel‐like fat mixture. (iii) Optimal values of Tc and Tf were related to the m.p. of the LM‐fat and HM‐fat, respectively. (iv) Temperature variations of SFC as well as X‐ray diffraction spectra showed that the melt‐mediated transformation from α to β of the HM‐fat crystals was a prerequisite to reveal the gel‐like behavior. Consequently, the fat mixture revealing the gel‐like behavior might be called β‐fat gel.