Preparation And Processing Characteristics Of Konjac Gel Based Fat Analogue

The flavor,texture,and mouthfeel advantage of fat may lead to excessive intake,risking our health.With increasing demand for low-fat foods,fat analogue has become a new research focus because it possesses the sensory property of fat but aviod fat intake.Many studies in this field had focused on making it into an emulsion system or fat cube to simulate the properties of fat,while ignoring to simulate the texture and related properties of bulk fat.Therefore,in response to the industrial needs of block fat,this project used konjac flour and soybean oil as the main raw materials to try to prepare konjac gel based fat analogue,and based on its commonly used storage and transportation conditions,to explore its freeze-thaw stability in the frozen storage process.Furthermore,the processing properties of konjac gel based fat analogue were evaluated,including cooking,steaming,frying and roasting.The main findings are as follows:1.The poor solvent ethanol of konjac glucomannan was innovatively introduced in the preparation of konjac gel based fat analogue,and the effects of ethanol content,KGM content,oil content and freeze-thaw treatment on the texture properties,gel strength,tenderness,color,p H and water and fat binding properties of the konjac gel based fat analogue were investigated.According to the findings,ethanol could affect the texture properties of the konjac gel based fat analogue during freeze-thaw process,making it closer to the texture of pork backfat.Konjac gel based fat analogue with 6 wt% and 8wt% ethanol had similar texture properties to pork backfat after 1 freeze-thaw cycle.Appropriate amount of ethanol could not only reduce the syneresis rate of the konjac gel based fat analogue,but also effectively weaken the damage to the network structure caused by freeze-thaw treatment.The p H value of konjac gel based fat analogue was between 8.4-8.8 and the moisture content was above 74%.Compared with pork backfat,it had a higher moisture content and lower energy.Meanwhile,the brightness value of konjac gel based fat analogue was similar to that of pork backfat.2.The freeze-thaw stability of konjac gel based fat analogue with ethanol introduced during frozen storage was studied,and the effects of different frozen storage time and freeze-thaw cycle on the mechanical properties,physicochemical properties and microstructure of konjac gel based fat analogue were compared.The results showed that the freeze-thaw stability of konjac gel based fat analogue was better when the ethanol content was 8 wt% or the KGM content was 3.5 wt%,and there was no sharp increase in hardness during frozen storage process.Konjac gel based fat analogue with 8 wt%ethanol was frozen for 21 days or after 3 freeze-thaw cycles and still had similar texture properties to pork backfat,realizing the effective regulation of the sharp changes in texture during the freeze-thaw process.The mechanical properties of konjac gel based fat analogue with 3.5 wt% KGM did not change significantly during 28 days frozen storage.After 5 freeze-thaw cycles,the hardness,chewiness,tenderness and gel strength of konjac gel based fat analogue were similar to that of pork backfat.During frozen storage,the L* value of the konjac gel based fat analogue changed less and was similar to the lightness value of pork backfat.3.To study the cooking characteristics of konjac gel based fat analogue,the effects of cooking time on the edible quality of konjac gel based fat analogue were investigated under the four cooking methods of cooking,steaming,frying and roasting,and their texture properties,color,cooking loss,shrinking ratio and sensory evaluation were analyzed.The results showed that the properties of the konjac gel based fat analogue treated by each cooking method had the same trend with the cooking time.With the prolongation of the cooking time,the hardness,chewiness and gel strength of the konjac gel based fat analogue gradually decreased.The konjac gel based fat analogue had lower cooking loss between 1%-12% and lower shrinking ratio after cooking and steaming,while the cooking loss were higher between 20%-60% after frying and roasting,with significant volume shrinkage during cooking.The cooking methods of cooking and steaming had less effect on the color of konjac gel based fat analogue,while frying and roasting caused a noticeable change in the color,from white to golden.From the sensory evaluation results,it could be found that the fried and roasted konjac gel based fat analogue had better flavor and mouthfeel.