Fat crystal network reinforced plant-derived polysaccharide-based oleogels

Abstract

Most traditional fats for the food industry take hydrogenated oils and high saturated oils as the base material. However, hydrogenated oils and high saturated oils were widely questioned because of the threat to health caused by trans and saturated fatty acids. Oleogelation is a potential strategy to structure liquid oils to replace traditional fats in foods. The aerogel-templated method allowed plant-derived polymers (polysaccharides and proteins) to prepare oleogels. Methyl-cellulose and xanthan gum were dissolved in waters and aerated to prepare aqueous foams. The molecular network of polysaccharides in aqueous foams was rapidly fixed by the ultra-low temperature freezing method, and aerogels were obtained by freeze-drying. The ultra-low temperature freezing method made aerogels have an average pore size of 36.7 μm and improved the porosity. Because of the open network in aerogels, there was a gap between oleogels fabricated by aerogels and traditional fats. Hence, fat crystals were used to further enhance the network structure in oleogels. Vegetable fats (Palm oil, coconut oil, palm kernel oil, and palm kernel stearin) were used to replace 50% of the soybean oil to enhance oleogels made by the aerogel-templated method. Aerogels had stronger oil absorption ability for oils containing PKS and PKO, reaching 39.6 and 38.24 g/g, respectively. Enhancement effects of different vegetable fats on oleogels were analyzed by the oil binding ability, polarized light microscopy, and rheological test. The crystal network formed by coarse crystals could endow oleogels with higher oil binding ability and more robust solid properties but result in more sensitivity to temperature. Through FTIR analysis, the hydrogen bond between polysaccharides constituting the polymer network was detected. The addition of vegetable fats could make oleogels physical properties of traditional fats, thus making oleogels further in the traditional fat replacement.