| Oleogelsation prepared by gelatinization of vegetable oil has the advantages of zero trans and low saturated fatty acid,and is considered as a new oil product to replace the traditional plastic fat.Searching for effective,healthy and food-gradeo leogelators was a key challenge in the commercial application of oleogels.In this study,monoglyceride?MAG?,mono-diglyceride fatty acid ester?DS?,polyglycerin fatty acid ester?PGEs?and sodium stearoyl lactylate?SSL?were used as oleogelsators to prepare oleogels.The macroscopic properties and microscopic structure of oleogelss were evaluated.In addition,the effects of oil-water ratio and addition of oleogelators on the construction and microstructure of emulsion gel were explored.Finally,the application of oleogelss in baking products was evaluated.The main contents and conclusions are as follows:First of all,direct dispersion method was used to prepare MAG and DS oleogels.The macroscopic properties and microstructure of oleogels were investigated by physical property analyzer,rheometer,pulsed nuclear magnetic resonance?pNMR?,polarizing light microscope?PLM?,X-ray diffraction?XRD?and fourier transform infrared spectroscopy?FTIR?.The results showed that the structure,fatty acid composition and content of the organogelators affected the crystal morphology and distribution in the organogels which affected the hardness,oil retention rate and thermodynamic properties.The network structure with uniform crystal distribution can provide strong mechanical hardness and oil-binding ability.Three-dimensional network structure formed by mixed crystal of monoglyceride and diglyceride is superior to organogels prepared by single component monoglyceride in hardness and oil-binding ability.Both MAG and DS organogels appeared a diffraction peak around 4.5?,and a characteristic peaks of hydroxyl stretching vibration appear at 3300-3400cm-1,indicating that hydrogen bonding may play a positive role in the formation and stability of the reverse sheet structure.Secondly,the above analytical techniques were used to investigate crystallization characteristics and macroscopic properties of oleogels prepared by PGEs and SSL.Results showed that the high concentration organogelors promoted the formation of the network structure,and increased the number of crystals and made the distribution of crystals more dense.The thermodynamic properties,oil-binding ability,hardness and solid fat content increase with the addition of the organogelators.Diffraction peaks of PGEs oleogels appeared at 4.56?and 4.15?,while diffraction peaks of SSl oleoglels appeared at 37.51?,4.58?and 4.12?.Results indicated that the lamellar crystals structural and?-crystal coexists in organogels.The absorption peak of stretching vibration of–OH were observed in FTIR spectra of PGEs oleogels,while not appeared in FTIR spectrum of SSL oleogels.Thirdly,phase diagrams and the microstructure of the emulsion gel were investigated.Pictures of fluorescence microscope showed that the emulsion gel was oil-in-water.The droplet size and fluidity of emulsion gel increased with the increase of the water ratio.The PLM images showed that there is crystal birefringence at the oil-water interface,and the emulsion gel has a broad diffraction peak at 4.6?indicating a hydrated two-layer structure at the oil-water interface.Finally,oleogels were applied in bread and puff pastry in order to replace the margarine and shortening.The properties including fatty acid composition,sensory properties and physical properties of the bread and puff pastry produced by the oleogel,sunflower oil,margarine and shortening were measured and compared,respectively.The bakery products produced by the oleogel contained low content of saturated fatty acids?around 12%?and no trans fatty acids,while the baking content of margarine and shortening has a SFA content of more than 50%.The bread produced by oleogel have typical fermented bubble structure,and whose hardness and elasticity were better than those of bread made by sunflower oil but slightly worse than bread made by margarine or shortening.In the sensory evaluation,the score of sunflower oil puff pastry at appearance,color,taste and taste were lower,while the appearance,color,taste and overall acceptance of puff pastryt produced by oleogels were not much different from those of puff pastryt produced by margarine and shortening.It was found that the oleogel has the potential to replace margarine or shortening used in bakery products. |
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