Study Of Bigels Preparation Based On Soybean Oil 2-monoglyceride And Its Capacity As Delivery System

Semi-solid lipids endow food specific functional characteristics,but contain a large amount of saturated and trans fatty acids which have negative effects on human health.Emulsion gelation is a new method to prepare semi-solid lipids by substituting water phase for part of fat,and it can give semisolid lipids the advantages of plasticity and low-calorie,but it still has several disadvantages,for example,thermal instability.The occurence of bi-phase gel(bigel)seems to be a promising way to solve the above problems.In this study,the thermal emulsification method was used to prepare bigels based on soybean oil 2-monoglyceride,and the structure,stability and function as carrier of bioactive substances were studied,which provided theoretical basis for the development and application of new food-grade semi-solid lipids.Firstly,a novel method of two-step enzymatic alcoholysis of soybean oil was used to prepare 2-monoglyceride(2-MG).Oleogels were prepared with rice bran wax(RBW)and 2-MG as mixed gelling agents.The results showed that the optimal conditions were as follows: substrate weight ratio of 2:1(w/w),10% Lipozyme 435(w/w total reactants),and 4 hours of reaction time at room temperature.Under these conditions,the 2-monoglyceride yield reached 40.69%.The unsaturated fatty acids(UFAs)at the sn-2 position reached 93.7%.Soybean oil-based oleogels were prepared by the mixture of 2-MG and RBW.There may exist synergistic effect between 2-MG and RBW in the gelation process.In addition,the oleogel prepared by the mixture of 2-MG and RBW was used as the lipid phase,and the soybean protein isolate solution and ?-Carrageen hydrogel were used as the aqueous phase.The oleogel emulsion(emulgel)and bigels were prepared by thermal emulsification method.The differences in structure and function between emulgels and bigels were characterized systematically by using texture analyzer and so on.The results show that,compared with emulgel,the addition of hydrogel can reduce the hardness and cohesiveness of the bigel system.Besides,the emulgel basically has no swelling ability,but the swelling rate of the sample with80% hydrogel can reach 30.05%.When the proportion of hydrogel in the bigel is greater than 50%,the accelerated-leakage rate of the gel system is maintained at12% ? 14%,and the gel system has better "water-oil retention".The bigel system possess better water-oil holding capacity and swelling ability,which provide potential role of loading bioactive substances and promoting its release.The freeze-thaw thermocycling and long-term storage methods were used to investigate the storage stability and ?-Carotene(BC)retention capacity of gel systems.The effects of emulgels and bigels prepared with different formulations on the release of BC in simulated gastrointestinal digestion were investigated by in vitro simulated digestion experiments.Blood compatibility test and MTT assay were used to investigate its biocompatibility.The results showed that,after repeated freeze-thaw thermocycling treatment,the sample with higher proportion of oleogel in emulgel possessed better stability.Emulgel samples with oleogel proportion of 80%,60% and50% were stored in the dark under 30 ? for 12 days,the BC retention rate of the samples were 50.27%,45.25% and 41.6% respectively(sample with proportion below50% was under corruption).BC retention of Bigel samples were 42.26%,40.58%,40.55%,37.43% and 33.23% respectively,the low temperature(4?)and storage in the dark can improve BC retention rate in gel system.Meanwhile,the system with high gel strength can provide better protection for the BC.The release rate of BC was the highest in emulgels with low oleogel fraction and bigels with low emulsion gel fraction.The hemolysis rate was less than 5% in the presence of all gel systems in the blood compatibility test.Compared with the control group,there was no significant difference(p>0.05)in the proliferation index of Caco-2 cells in the presence of leaching solution of emulgels and bigels,which proved that the gel systems possessed good biocompatibility.The construction of bigel provides a novel idea for the development of semi-solid fat.