Study On Preparation And Properties Of Rice Starch-Based Fat Substitute

Fat substitutes were prepared by enzymatic hydrolysis with rice starch as raw materials. The regression equation and optimal conditions of the preparation of rice starch-based fat substitutes (RSFS) were obtained through the central composite experimental design.The molecular weight distribution, textural characteristics and fundamental properties were analyzed by:high performance liquid chromatography/HPLC, texture analyzer/TA, scanning electron microscope/SEM, and viscometer.The results are as follows:RSFS with DE value2, which got strong gel strength, had a broad molecular weight distribution and polydispersity, and the situation with DE value4was quite the reverse. Molecular weight of RSFS decresed with increase of DE value and enzymatic hydrolysis; whereas the gelatin strength of RFFS decresed accordingly.The granules of rice starch present polygon and the average grain size is7μm. Compared with native starch, the surface of starch hydrolysate granules was eroded, and the size became smaller. The the average grain size was3-5μm.The apparent viscosity of RSFS decreased with increase of temperature at the same shear rate. The apparent viscosity of fat substitutes decreased with the increase of shear rate under same temperatures, which should belong to "pseudoplastic liquid"The gel strength of RSFS decreased with the increase of DE value, and The gelatin formed by DE value2-4felt smooth, no sense of particles. Fat substitutes of DE5,6cann’t form or can only form weak gelation at a concentration of30%. Thus, RSFS with DE2～4were more suitable for application in the food industry.Compared with the rice starch, RSFS had better water retention property, higher clarity, less retrogradation, nicer hygroscopicity and freeze-thaw stability. Water retention property, freeze-thaw stability of rice starch fat substitutes reduced and clarity, retrogradation, hygroscopicity increased with increasing of DE value. A suitable fat substitute with proper DE value can be chosen according to the different situations.The effect of the DE value of RSFS, substituted rate for fat, the content of egg yolk on the viscosity and sensory characteristics of low-fat mayonnaise was studied by single factor orthogonal experimental designs. The sensory evaluation showed that it had higher stickiness, workability smooth taste, which was analogous to full fat mayonnaise.