Studies On Preparation,Properties Of Pullulanase Enzymatic From Sweet Potato Starch And Its Application In Noodles

Sweet potato noodles is not only a kind of traditional Chinese food,but also is one of the common dishes on the table.The sweet noodles is an irreversible gel after gelatinization of starch by heat, Because of the low amylose content,sweet potato starch can not form a strong gel after pasting,the noodles have been made of easily breaking and other defects. Pullulanase is a highly specific starch debranching enzyme, amylopectin can in α-1,6-glucosidic bond hydrolysis, to form a free amylose molecules, thereby improving the quality of potato starch noodles. In this study, sweet potato starch the raw material to hydrolysis starch by pullulanase. and from the physical and chemical properties, pasting properties, gel properties and characteristics of microscopic particles in four areas were compared with native starch. Finally, as a raw material used in the processing of sweet potato noodles, get better quality and sensory evaluation of sweet potato noodles. It is hoped to provide theoretical basis on selection and quality improvement of sweet potato starch for noodles-processing.The main contents and results of this paper are as follows:(1) Preparation of Pullulanase enzymatic from sweet potato Starch:One-factor-at-a-time and orthogonal array desigin methods were used to optimize the experimental conditions based on the setback and Amylose content of starch.The optimal conditions for hydrolysis were found to be hydrolysis at55℃and pH4.5for15h with enzyme loading of48ASPU/g, the result showed that the setback of starch up to1925cp.The Amylose content of starch up to25.21%. The hydrolysis under the conditions of retrogradation of the starch reaches a maximum1925cp, the highest amylose content of25.21%.(2) The comparison of pullulanase enzymatic starch and the sweet potato starch in physical and chemical properties, pasting properties,particle morphology gel properties and microstructure shows that:hydrolysis of starch with a high amylose content, amylose content increased from20.368%to25.21%. as compared with original starch swelling power and solubility were reduced At40℃～90℃,indicating that hydrolysis of starch inside the binding capacity than the original starch. Because the reticular formation of more solid after pasting amylose, pullulan to enzymatic hydrolysis of starch to20.3%transmittance, higher transmittance than the original potato starch7.8%. Retrogradation enhanced. Pullulanase enzymatic hydrolysis of starch freeze-thaw resistance than native starch,48h after analysis of water is lower than the original starch. Through rapid viscosity analyzer for enzymatic hydrolysis of starch and raw potato starch pasting properties were measured pullulanase enzymatic hydrolysis of starch sweet potato starch compared with the original peak viscosity reducing1219cp, trough viscosity reduces1148cp, final viscosity lower the224cp, regenerative value increases from765cp to1925cp. Pasting temperature increased from75.4℃to81.7℃. Texture Analyzer and by electron microscopy scanner comparison of starch gel properties, gel strength after pullulanase enzymatic starch gel increased from141.05g to261.00g, gel rupture strength increases from266.10g to388.20g, gel viscosity from27804Pa·s reduced to18852.09Pa·s. Hydrolysis of starch granules in microscopic cracks surface is not smooth, there are some depressions points card Mingpululan enzyme hydrolysis of starch has a role. Hydrolysis of the starch gel structure formed dense gel structure to form a tight, no pores.(3) To determine the ratio of the amount of polysaccharide gums:determine the total amount of Polysaccharide gums as0.1%to the sweet potato noodles.paste soup transmittance, broken rate and cooking loss rate as the rate of response, use mixture design to optimize the number of three-factor experiment design, and quadratic regression based on the measured values obtained quadratic regression model: Ytransmittance=7.32668A+5.09116B+5.90239C+53.53024AB+37.42542AC+44.77474BC; Ybroken-rate=106.86993A+177.32701B+127.27559C-1681.15325AB-1521.7472AC-1388.93039BC; Ycooking lossrate=96.77664A+163.25729B+115.19238C-2231.79045AB-995.81759AC-455.5239BC. And use Deign-expert optimization feature four groups, optimize the sensory score by fuzzy math,the highest score formula is:0.04%addition of xanthan gum,0.019%addition of carrageenan,0.041%addition of konjac gum.(4)The comparison of noodles qualities:mung bean vermicelli compared with the two kinds of noodles which raw material lis hydrolysis starch or original starch with polysaccharide gums added to it,the results showed that enzymatic hydrolysis starch noodles has broken rate of7.67%, light transmission rate of0.771, cooking loss rate of7.85%.Either breaking rate, light transmittance and paste soup cooking loss rates are better than the quality of the original starch noodles, and the noodles close to the quality of mung bean starch.The sensory evaluation of the three noodles by fuzzy math shows that the scores of hydrolysis starch noodles、mung bean starch noodles and the original sweet potato starch noodles were88.0875,87.6175,70.83. The result shows that pullulanase hydrolysis starch noodles higher than the mung bean vermicelli, is much larger than the original starch noodles.