Gel-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 T c (crystallization temperature) from 70°C and subsequent heating to T f (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 T c and T f 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.Paper no. J10361 in JAOCS 80, 263-270 (March 2003).KEY WORDS: Cocoa butter, fully hydrogenated rapeseed oil, gel-like fat, polymorphism, sal fat olein.Fats and oils are, in general, employed in industrial applications in solid (crystalline), semisolid, emulsion (oil-in-water and water-in-oil), gel, and liquid states. A gel state is defined as a two-phase colloidal system consisting of a solid and a liquid in a more solid form than sol, although there are various definitions representing the complicated nature of gel states (1). Because of their smooth texture, viscoelasticity, appearance, easy handling, and comfortable mouthfeel, gel materials have attracted much attention in food, cosmetic, and pharmaceutical sciences and technology (2-5). Therefore, a wide variety of research into gel phases made of polysaccharides, proteins, and other biopolymer materials has been performed (6,7). In a gel phase made of lipid emulsifiers and water, a lamellar-type lyotropic liquid crystal (LC) phase is formed at elevated temperatures. In the LC phase, a water phase is swelled into a continuous lamellar LC phase. When this LC phase is cooled to undergo the transformation from the LC phase to a crystallization phase, the lamellar structure involving the swollen water phase is maintained, forming a highly viscous phase called an α-gel phase (8-10). Further cooling forms a rheologically hard phase called a coagel. T...