Study On The Preparation And Structural Properties Of Oleogel Based On Monoglyceride Oleogelator

Oleogelation is a method of forming structured oil system by using vegetable oils.This technology is one of the important methods for preparing solid fat substitutes,and plays an important role in controlling the rate in vitro digestion and transferring active substances.However,current oleogel products have some disadvantages such as low oil bonding capacity,poor structure recovery ability,and easy oxidation of vegetable oils.The resultant food presents a rough structure and reduced flavor,which is greatly different from the food prepared by traditional solids fat.In this work,glycerol monolaurate(GML)was selected as an oleogelator to explore the effects of oleogelation on the physical properties of oleogels and oleogel emulsions,and discuss the effects of oleogelation on oxidation stability,in vitro digestion and other properties.The main contents of the investigations were summarized as follows:(1)GML camellia oil-based oleogel was fabricated by direct dispersion method and the effect of GML oleogelator on the stability of oleogel system was studied.The critical gelation concentration of GML was 3 wt%,and a densely needle-like crystal network was formed within the oil.With the increasing GML concentration,the thermal stability was enhanced due to the occurrence of van der Waals force and intermolecular hydrogen bonds.Meanwhile,soy protein isolate(SPI)was utilized as the emulsifier to prepare oleogel emulsions.Compared with pure liquid oil emulsion,a compact three-dimensional network structure was formed in the oleogel emulsion,and showed the larger droplet size.After adding10 wt% GML,the POV and TBARS values of the oleogels were reduced by 67.8%and 34.4%,respectively.The POV and TBARS values of the oleogel emulsions were reduced by 36.4% and 23.9%,respectively.The results showed that the oxidation rate of oleogel and oleogel emulsion with GML was lower,showing the improved oxidation stability.(2)In order to compare different mechanisms of oleogel,the direct dispersion method,the emulsion template method and the combined oleogelation method were used to prepare oleogel.The differences of structural properties and digestion characteristics of oleogels were analyzed.Among the three methods,oleogels prepared by direct dispersion method showed needle-like morphology,poor oil bonding capacity,low hardness,and were dependent on heat and frequency.The SPI-based oleogels prepared by emulsion template method exhibited a sheet-like structure and strong resistance to heat,in which a threedimensional network structure was formed.The SPI-based oleogels,which was mainly based on intermolecular hydrogen bonds showed a better oil bonding capacity and the highest viscosity recovery percentage.The oleogels obtained by the combined oleogelation method were filled with GML-cured oil in the SPI network,and showed the highest oil bonding capacity and moderate resistance to heat and frequency.The oleogel with 6 wt% of GML and 6 wt% of SPI presented the highest free fatty acid release rate and maximum release amount,and the release amount was increased by 36.7% compared with pure oil,indicating the significantly improved oil digestion rate.