| Resistant starch (RS) was manufactured by methods of heating, autoclaving, autoclaving-cooling cycles, acids, enzymes and hydrolysis of acids or enzymes combined with autoclaving-cooling cycles. The effect of preparation process was measured by content of resistant starch and its thermostability. The relationship between RS content and types of starch amylose content, degree of hydrolysis, debranching degree were investigated. Thermodynamic properties and particle morphology of the resistant starch was determined by differential scanning calorimetry (DSC) and scanning electron microscope (SEM), respectively. The results of the research were as follows:1. Resistant starch was manufactured by methods of heating, autoclaving, autoclaving-cooling cycles, acids, enzymes The RS content were not significantly improved by85℃heating method, but thermostability significantly increased from68.79%to89.65%. RS content was significantly increased from4.87%to10.23%,12.56%, thermostability was up to92.38%and94.46%by autoclaving and3times autoclaving-cooling cycles, respectively. The method of hydrochloric acid and citric acid was better than that acetic acid when resistant starch was manufactured by only acid hydrolysis. The thermostability of resistant starch which was manufactured by acids was at range from75.28%to87.48%. The RS content was higher when pH value rang from2.5to3.0. The highest RS content were7.33%,7.39%respectively when acidolysis of starch was sustained for12h in pH2.5of hydrochloric acid and pH3.0of citric acid at room temperature. Content of resistant starch and its thermostability got the highest7.37%and95.15%respectively when the enzyme dosage of the thermal stability of alpha amylase was30U/g starch, enzymatic hydrolysis time was15min. When the dosage of pullulanase was8U/g starch, enzymatic hydrolysis time was16hours, RS content got the highest13.69%.2. When acidolysis or enzymolysis combined with autoclaving-cooling cycles to product resistant starch, the cycles were influenced RS content before acidolysis or enzymolysis. It was2autoclaving-cooling cycles before pH2.5hydrochloric acid hydrolysis12hours, then conducted more1cycle, the RS content and thermostability was14.42%and90.31%respectively. It was1autoclaving-cooling cycles before30U/g starch dosage of high temperature resistant alpha amylase hydrolysis15minutes, then conducted more2cycle, the RS content and thermostability was12.16%and91.68%respectively.The RS content and thermostability got the highest value (17.94%,94.63%respectively) before digestion of pullulanase was3times processing of autoclaving-cooling cycles, RS content was31%more than method of pullulanase, was3.68times of RS content of native starch, was higher than other technologies.3. The changes of RS content was different after waxy maize, cassava, corn and potato native starch was conducted by the method which included heating, autoclaving and autoclaving-cooling cycles. But thermostability were significantly improved, corn starch were more suitable for the preparation of resistant starch than other starch.,The influence of amylose content to resistant starch was different in different processing conditions, but RS content were rise with the increasing of amylose content in the same process conditions. Relationship between starch hydrolysis degree (DE) and RS content were not obvious micro negative correlation (r=0.190, p=0.481>0.05), the amylose content decreased with starch DE value increasing. RS content increased with debranching degree increasesing. But RS content tended to be stable when degree increasesing was more than75%. The relationship between RS content and debranching degrees was significant positive correlation (r=0.573, p=0.013<0.05), amylose content increased with the debranching degree increasing in low debranching degree (10%-40%), amylose content showed decline after debranching degrees more than40%.4. DSC results showed that:The pasting temperature, peak temperature of resistant starch were significantly higher than the original starch.Gelatinization enthalpy of resistant starch was increased from4.37J/g to12.26J/g with RS content increased. SEM results showed thatoriginal circular or elliptic contour, smooth surface of starch granules had changed dramatically flat, particle shape had changed into irregular gravel type. Surface with the increased of heat treatment temperature and the cycles of autoclaving became greater degree of squamous ups and downs. The resistant starch were prepared by method of acids, high temperature resistant alpha amylase, pullulan enzymatic, which surface appeared small hollow hole, but RS made by acid solution or enzyme solution joint autoclaving-cooling cycles didn’t appear the phenomenon. |
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