Study On The Preparation And Physic-chemical Properties Of Malt Starch And Its Porous Starch

Starch is a kind of rich,economical and renewable resource.But the industrial applications of starch are greatly limited because of its inherent properties.Therefore,the modification of starch has gradually become the hotspot of research.At present,the process of preparing porous starch has some disadvantages,such as difficult to operation and poor product stability.The research showed that germination could improve the nutritional value of grains significantly and had many effects on the structure of starch granule and the starch paste properties.What's more,the process of germination is stable.However,the research of the malt starch physic-chemical properties,especially the changes of the physico-chemical properties of starch during germination,has not yet attracted sufficient attention.Therefore,it has great theoretical significance and practical value to carry out the related research in this field.Beer malt,medicinal malt and wheat malt were selected to investigate the physic-chemical properties of malt starch in this paper.On this basis,the porous starch was prepared by the natural germination process of medicinal malt.And the process was controlled through the length of malt.Meanwhile,the properties of porous starch,such as adsorption property were determined.The experimental results indicated that the amylose contents of beer malt,medicinal malt and wheat malt were 28.64%,30.3%and 29.24%respectively,which were decreased after the germination;three malt starches still maintained the granule shape of raw starch,but the B type starch granules were significantly increased in wheat malt starch;three malt starches crystalline structure were still A type,while the crystallinities were increased,and the crystallinities of beer malt,malt malt and medicinal starch were 12.35%,12.5%and 13%respectively;the starch paste properties of three malt starch changed significantly,the transparency,solubility of malt starch pastes were increased while the swelling power were decreased significantly,and medicinal malt starch paste stability was significantly better than raw barley starch;the syneresis rates of beer malt,medicinal malt and wheat malt were 29.4%,30.47%and 31.2%respectively,the freeze-thaw stability of malt starch pastes were increased significantly.The process of porous starch preparation by the germination of medicinal malt:soaking time 24h,cultural temperature 20?,air humidity 22%.There were uniform pores formed on starch granules when the bud length was 3?4 cm and some pores even extend to the interior of starch granules.At this stage,the medicinal malt starch had a good form of porous starch,and malts of this stage were specifically cultured for the preparation of porous starch.The researches of adsorption properties of porous starch showed that the water and oil absorption of porous starch were 109.55%and 115.36%,and the methylene blue adsorption was 8.23 mg/g.The adsorption capacity of porous starch was significantly better than ungerminated medicinal malt starch.Using methylene blue as an adsorbate,researches on the adsorption thermodynamics and kinetics of porous starch showed that Langmuir isotherm equation could well describe the adsorption behavior of porous starch on methylene blue,and the adsorption process was a spontaneous and endothermic physisorption process.The pseudo-second-order provided better correlation with the kinetic process.In other words,adsorption rate of the porous starch was proportional to the square of adsorption concentration under ideal conditions.