Preparation Process Optimization And Properties Analysis Of Corn Resistant Starch Preparated By Psychrophilic-pullulanase

The study adopted autoclaving combining with psychrophilic-pullulanase debranching treatment by using corn starch as raw material, and studyed the properties of resistant starch. It provided theoretical guidance for applications of psychrophilic-pullulanase in food industry and industrial production of resistant starch. Summarized as follows:1. We studied the strain Pseudoalteromonas sp. strain NX-1 to know the enzymatic properties through the single factor test and orthogonal test.Through study we obtained the optimum culture conditions of strain NX-1, optimal enzyme fermentation culture conditions, the optimal medium and the optimum inoculum.The results showed(1) the optimum temperature was 20 ℃, the optimum p H was 7, under the optimum conditions, the half-life of the enzyme was about 120 min.(2) The strain NX-1 fermentation medium composition was ucrose content 1.5%(w/v), peptone 1.5%(w/v), CaCl2 0.05%(w/v),Na2HPO4 0.6%(w/v).(3) Under this condition, the optimum inoculum was 4%(v/v), the optimum liquid volume was 80mL/250 mL. After optimization of enzyme production strains was up to 25.17U/mL, compared to the previous optimization improved by 25.1%.2. By orthogonal optimization autoclave-Standby process parameters corn resistant starch hydrolysis method through orthogonal test to optimize the process parameters, the results showed that the optimum optimized for milk quality corn starch fraction was 15%, the amount of heat α-amylase was 7U/g, psychrophilic-pullulanase adding amount was 10U/g, psychrophilic-pullulanase reaction time was 11 h, the condition under the resistant starch yield of 16.838 percent, compared with before optimization to improve 11.732%.Characteristics of starch samples showed that the solubility of resistant starch and water holding capacity were higher than the original corn starch; Scanning electron microscopy showed that the particle morphology of corn resistant starch was irregular lumps, the particle morphology of raw corn starch was destroyed; X-ray diffraction pattern showed that the new crystal structure was found in the resistant starch, crystal structure of maize starch were belong to type A, corn resistant starch was mixed type B and type V; DSC experiment showed that the corn resistant starch dataes of To, Tp, Tc and △H all improved, so resistant starch had better stability than corn starch.