چكيده به لاتين
Starch after cellulose is the most abundant polysaccharide in the world. However, due to the high tendency of colloid formation and insolubility in water there are many limitations for using in industry. If starch can be modified by using physical, chemical and enzymatic method, it can be used extensively in various industries such as food, pharmaceuticals and and health. In this experiment we study use of ultrasonic waves, thermal-acidic hydrolysis and enzymatic hydrolysis by immobilization of alpha-amylase on magnetic nanoparticle as physical, chemical and enzymatic methods, respectively. First, the thermal-acidic hydrolysis of starch at different pHs (3.5, 4.5, 5.5) at low (60, 65, 70 ˚C) and high (90 °C) gelatinization temperature by using ultrasonic waves was investigated. The magnetic features of the nanoparticles were investigated in the presence of acidic hydrolysis starches. Optimal conditions of starch modification in terms of redusing sugar production, maximum release of amylose and preservation of magnetic properties of nanoparticles in thermal-acidic hydrolysis of starch 0.5% with pH=4.5 at high gelatinization temperature and affected by ultrasonic waves for 30 minutes were determined. Then the parameters of concentration (0.5 and 1%) and initial starch pH (3.5, 4.5, 5.5), temperatures (40 and 50 ˚C), time (10, 15, 20 minute) and immobilized enzyme volume (0.1-1 ml) in enzymatic hydrolysis was investigated using one factor at a time design. Finally, modification and enzymatic hydrolysis of starch were investigated simultaneously for 15 minutes using factorial design 23. Concentration of starch 0.5% and starch initial pH=4.5 and temperature=50 ˚C were determined as optimum conditions. The experiment also showed the possibility of immobilized enzyme reusing, which can retain 40% of its ability to produce redusing sugar and retain magnetic features of nanoparticles after 6 cycles.
