Study On Preparation Of Fat Simulators Based On Artificial Lipid Droplet And Modified Konjac Glucomannan

The use of fat substitutes to replace animal fat in meat products can achieve the goal of fat reduction without affecting the texture and taste of meat products.Blocky fat simulators need to have the characteristics of no morphological changes during the processing of meat products.However,most fat simulants prepared with traditional raw materials and processing techniques have some problems.Their texture properties and sensory qualities are far inferior to those of real animal fat.In this study,the lard substitute lipid was prepared with mixed vegetable oil and it was embedded in phosphatidylcholine to form an artificial droplet emulsion.Secondly,the carboxylated konjac glucomannan was modified.And the fat droplet emulsion was combined with the mixed sol,which composed of carboxylated konjac glucomannan,octenyl succinate starch sodium and alginate sodium,to prepare a block of pork fat simulation.In addition,the physicochemical properties,processing properties,digestive properties and the effect on the structure of intestinal flora of fat simulants were investigated.The main research work of this paper is as follows:Firstly,mixed vegetable oil was used as the basic material to prepare vegetable lard substitute fat,and artificial lipid droplet emulsion was formed.Palm oil extract,shea butter extract and soybean oil were selected as the basic oils,supplemented with fat soluble gel factors and flavor regulators.After enzymatic transesterification and other steps,plant-based lard substitute fat with smooth texture was prepared.It had similar melting point,iodine value and texture properties to lard,and the content of Sn-2-palmitic acid could reach 43.30%.Using L-α-phosphatidylcholine as the source of phospholipid monolayer,the artificial lipid droplet emulsion was prepared by ultrasonic method.The optimal mixing ratio of 50 mg phospholipid,2.5 m L replacement lipid and 12.5 m L sucrose buffer was determined.Under the condition of400W ultrasonic for 80 min,the yield of lipid droplet was stable and the particle size remained around 500 nm.The lipid droplets were uniformly distributed in small spheres with good dispersion.Secondly,Konjac glucomannan was modified by carboxylation.The optimum reaction conditions of carboxyl modification of KGM were as follows:succinic anhydride 40%,45℃,4.5 h and p H 8.5.The carboxyl substitution degree could be up to 1.04 and the viscosity of sol system was reduced.The absorption peak of carboxyl group was observed at 1570 cm^-1 by infrared spectroscopy and a large number of angular fragments appeared on the surface of the modified KGM particles by scanning electron microscopy.The viscosity of modified KGM increased with the increase of calcium ion concentration,indicating that the carboxyl modification significantly increased the binding ability of KGM and calcium ion.At the same time,its water absorption capacity increased from 51.25 g to 63.69 g per gram of polysaccharide,and its solubility in 100 m L water increased from 0.61 g to 0.70 g.Cytotoxicity test showed that it had no toxic effect on the growth of human small intestinal epithelial cells and could be used in the preparation of fat simulators.Finally,the spray molding process and the characteristics of fat formation were investigated.In the mixed sol layer formed by carboxylated KGM,octenyl succinate starch ester and sodium alginate,the fat drops emulsion rich in calcium ions is sprayed,and the fat blocks are formed by repeated spraying brush.The optimal dosage of 100 m L system was determined as follows:6.0 g carboxylated KGM,7.0 g octenyl succinate starch,5.0 g sodium alginate and 5.0 g calcium chloride.The hardness,elasticity and cohesiveness of the fat blocks prepared were 2574.3 g,1.00 and 0.73,which were similar to the fat of cooked pigs.Its fat content is only 7.54%.At the same time,after hot processing such as boiling and frying,there is no obvious hole structure and bad odor.The digestibility was 31.03%after simulated digestion in vitro.In the end,in vitro fecal bacteria fermentation of healthy people was carried out with blocky fat simulator as carbon source.The relative abundance of short-chain fatty acid producing bacterias have been improved,such as Muribaculaceae,Lactobacillus,Faecalibacterium,Phascolarctobacterium and Akkermansia.