Studies On Starch Gelatinization And Its Application As Capsule Materials

As a kind of high molecular carbohydrate,starch is cheap,abundant and wide-distributed,which is commonly applied in many fields,such as food industry,medicine and bio-energy field.Gelatinization is an important property of starch containing many changes of physicochemical properties,starch gelatinization has a great influence on manufacture process and quality of starch-relative products.Studies on starch gelatinization always focus on changes of physicochemical properties before and after gelatinization,but structural changes of starch granules during gelatinization process are rarely reported,which are key to uncovering starch gelatinization process.Starch capsules is a kind of important application of starch in medicine field,and it has attracted world-wide attention as the promising plant capsules,however,due to the poor mechanical capacity and poor solubility of starch film,it’s hard for starch capsules to meet Chinese pharmacopoeia requirements in terms of disintegration time and friability.Based on those problems,firstly,we studied changes of cassava and potato starch granules over time in excess water at different temperatures,in terms of morphology,size distribution and amylose leaching,and compared those changes with native starch granules.We found that at the beginning of gelatinization（within 10 s）,those two starches swelled quickly and extensively,accompanied with leaching of amylose and loss of crystalline,increasing temperature and long time promoted further swelling and amylose leaching of starch granules.However,influence of temperature and time on cassava and potato starch granules are totally different,cassava starch granules kept intact during gelatinization,with a little amount of amylose leaching,while potato starch granules swelled violently,broke into swollen pieces above 70℃,with a significant amount of amylose leaching,besides,plenty of blue leaching contents dyed by iodine reagent was shown in microscope.Secondly,we developed the manufacturing process of starch capsules,and then studied the influence of different ingredients and their contents on capsule performances,including capsule appearance,yield,friability,disintegration time,water content and so on.The selected manufacturing parameters were quality fraction of starch（12%）,T_max of starch paste（70℃）,dipping molding temperature（60℃）,drying temperature（room temperature）;According to our test,when the relative humidity was 25%,glycerin,as a plasticizer,could decrease water content of starch capsules,leading to poor yield and friability;Mixture of 0.9%κcarrageenan（gelling agent）and 0.08%KCl（gelling aids）conspicuously improve yield and friability of starch capsules,but also increase disintegration time obviously;10%pullulan（film-forming agent）could improve yield of starch capsules,as well as greatly decrease their disintegration time;Mixture of 0.8%κcarrageenan,0.07%KCl and 4%pullulan could decrease friability of starch capsules maximum Ly,with a high yield.In conclusion,we decided that two formulations performing better capsules performances are 1)12%cassava starch and 10%pullulan,with their friability（67%）,disintegration time（15 min）,yield（90%）,water content（12.5%）;2)12%cassava starch,4%pullulan,0.8%κcarrageenan and 0.07%KCl,with their friability（47%）,disintegration time（41 min）,yield（78%）,water content（15.0%）...