The Research On The Properties Of Hydrolysis Of Corn Starch And Its Effects Of Vermicelli Quality

The relationship between the vermicelli with long-branches amylopectin is the key point of this article research.The molecular structure of three samples were investigated by gel permeation chromatography.The property of native corn starch(NS),slightly modified corn starch(SMS),highly modified corn starch(HMS) and their vermicelli were analyzed by X-ray diffraction(XRD), differential scanning calormeter(DSC), microstructure observation(SEM) and Fourier transfer infrared(FIR).To illustrate the difference of hydrolysis corn starch and corn starch properties, we use the XRD, SEM, DSC, FIR to text thermal properties,such as the apparent characteristics, crystallinity and others. After hydrolysis, amylose content increased significantly, solubility and swelling power increased, which makes the hydrolysis of corn starch granules inside molecules and the ability to reduce water retention, the nature of the changes will increase the expansion and paste soup fans degree. IR spectra showed that the process of starch modified do not produce a new group, exclude the other functional factors. Microstructure observation showed that native corn vermicelli has a smooth surface, it appears as a relatively stable space mesh structure,whereas the modified starch vermicelli has a rough surface and presents an unstable layer structure. Pasting peak natural com starch as a trend slow and wide exothermic peak, while the other two samples, there were two peaks. Intermolecular structural changes resulted in starch pasting temperature and energy required during enhancement, initial temperature and gelatinization enthalpy increase. The crystallinity of SMS and HMS decreased, starch gelatinization enthalpy rise relatied to the NS.In order to compare the differences in the nature of a sample of three vermicelli, the thermal properties, and edible apparent characteristics were tested,. As we can see,the solubility and swelling power of SMS and HMS is much higher than that of NC, the dissolution of starch is mainly due to amylose escape from the inflated starch grains and soluble amylose dissolved in water partially.The sensory evaluation of vermicelli showed that three samples has no difference in color, but in viscosity, retort resistance, chewiness and hardness, enzymatic corn vermicelli are significant difference with native corn vermicelli, enzymatic corn vermicelli has a large viscosity,poor retort resistance, low chewiness, hardness and other poor quality.These characteristics unsuitable for vermicelli. The gelatinization enthalpy of corn starch vermicelli is far higher than that of two kinds of modified starch, The native starch has only one wide and slow exothermic peak,whereas the other ones have two exothermic peak.The surface and cross-section of three samples showed that the NSV have space grid structure whereas SMSV and HMSV show an unstable layer structure.The gel filtration chromatography and molecular properties of NS,SMS and HMS showed that three kinds of starch were divided into two main peaks and a middle peak,the first sharp peak was the elution peak of amylopectin,β-amylase was a maltose invertase effect from the educing end α-1,4 glycosidic bond,Amylose can not be completely hydrolysis approximately because amylose contained low molar fractions of branched molecules, The table shows that after modifed,the β-amylolysis limit of Am was increased but the limit of Ap was decreased.Inferred from the experiment, vermicelli can be divided into a double helix structure centered crystal area network semi-crystalline and gelatinized starch amylopectin forming long chains of broken pieces filled without three structures amorphous regions. In the hydrolysis of corn starch, amylopectin branches after enzymatic solution, branched long chain is cut straight chain, reducing the number of amylopectin long chain branching, This enables the resuscitation of amylose gel network forming a branched structure is reduced, and the starch in the presence of more branched short chain, increasing the distance between chains, weakened within the chain, inter-chain hydrogen bond strength, So straight and long chain branching can not be a good move closer to each other and form a local ceramics, thereby preventing the gel network system to bundle these crystallites formed as the fulcrum. The strength of the gel network structure is a key determinant of the quality of good or bad fan, enzymatic Corn Starch low crystallinity, the gel structure is weak, the poor quality of fans.