Preparation and physical and chemical characteristics of rice highly transformed syrup

【Objective】The preparation process of rice syrup was studied， and its physical and chemical properties were analyzed to provide technical reference for the preparation of high-quality rice starch syrup products.【Method】 Using resistant crushed rice flour treated by double screw extrusion enzymatic pretreatment as raw material，the optimal scheme for preparing rice syrup was determined by using the combination of univariate and orthogonal test and the DE value as the investigation index， and the physical and chemical properties of rice syrup were determined by rheometer， color difference meter and high performance liquid chromatography.【Result】The optimal process conditions for rice syrup pre-paration were： saccharification time of 4 h， saccharification temperature 60 ℃，pH 4.0， Pullulanase additive 0.10%， beta-amylase additive 0.10%，glucose amylase 0.25%， and DE value was 91.3%， belonged to high conversion syrup（DE value>60%）. Through orthogonal test of the three enzymes， the main factor was beta-amylase additive>Pullulanase additive>glucose amylase addition. Rice syrup had the infrared characteristic absorption peak of sugar， and its sugar components were mainly glucose and maltose， accounting for 48.30% and 14.38% of the total sugar， respectively. Chromatism value（△E）was 5.33， indicating that the extrusion enzyme solution of rice syrup had good color and high transparency. 【Conclusion】The syrup prepared by double screw extrusion enzymatic pretreatment and enzymatic hydrolysis has good quality， high transparency and more delicate and soft taste， which can be added to various foods as the preferred sweetener.