Researches On The Preparation Of Stearate-carboxymethyl Konjac Glucomannan Ester By Microwave And Its Properties

Because KGM has many inherent properties, such as low solubility in water, its aqueous solution has visible dissolved konjac glucomannan particles even after placing a long time, the poor solution stability, weak alkali resistance ability and so on, which limited its application in the industry. This paper mainly reseached the preparation of stearate-carboxymethyl konjac glucomannan ester by microwave in moderate temperature conditions, and studied the basic properties of the product and its application in food.This paper were mainly in the following areas:1. In this study, stearate-carboxymethyl konjac glucomannan ester was prepared in solid reaction system, the optimum reaction parameters Of preparating CMK were obtained by orthogonal design, that was, the ratio of chloroacetic acid, konjac glucomannan and sodium hydroxide was 1.1:1:2.5, reaction temparture was at 75℃for 8min. Then the optimum reaction parameters Of preparating SCMK were obtained by revolving orthogonal combinatorial design experiment, that was, MS and NaOH dosage were 14% and 6% respectively, reaction condition was 85℃for lOmin.2.The properties of SCMK were determined, results showed that:compared with the KGM, CMK and SCMK had lower viscosity, and after placing for 48h, the viscosity of CMK and SCMK were still stable while that of KGM was significantly reduced.3.The stearate substitution of SCMK greatly impacted on the emulsification capacity. With the, the emulsification capacity of SCMK was increased as the increases of degree of substitution(DS). Research showed that pH significantly affected the emulsifying ability of SCMK, the emulsion was poor when pH was 5.0, but SCMK showed higher emulsifying capacity when at neutral or even alkaline pH. Media containing small amounts of NaCl had little influence on emulsifying properties, when more than 1% of NaCl, SCMK emulsifying ability decreased slightly, but the emulsion was still performed well emulsifying properties. Furthmore, we found that sugar can significantly increased the stability of system.4. From the ¹H-NMR Spectra of SCMK with DS of 0.02, we estimated the HLB value was 13.01, which indicated that was an oil/water emulsifier. The FTIR spectra of CMK showed that there were significant CO- and-OH absorption peak at wave 1325.38 cm^-1 and 2340.20 cm^-1, the peak at wave 1622-1627 cm^-1 represents C=O. compared with infrared spectra of CMK, SCMK infrared spectra has no obvious diffenent absorption peak, but the absorption peak decreases at 2161.84cm-1 and 2360.74 cm^-1.5. Thermal gravimetric analysis showed that, the significant weight loss of KGM begin at 261.5℃, while CMK at 252.87℃and SCMK at 257.34℃,that indicated thermal stability of SCMK and CMK were lower than that of KGM.6. we studied on the impacts of SCMK on biscuit, the result showed SCMK could reduce the dough stickiness and the number of surface bubbles of biscuit. When adding 0.6% of SCMK, the number of surface bubbles was significantly decreased, biscuit shape, color, taste, and organizational status had been improved as the increasing of SCMK. When adding 0.8% of SCMK, biscuits with attractive golden yellow became bulky, delicate taste. Sensory evaluation analysis shows that:AS the increasing of SCMK, hardness of biscuits decrease, and sensory analysis score increased, When adding 0.6% of SCMK, the biscuits showed best brittleness.