| Summary: | 碩士 === 東海大學 === 食品科學系 === 106 === Starch is mainly composed of amylose and amylopectin. Starch is tremendously used in many food applications, such as a thickener agent, colloidal agent, colloidal stabilizer, bulking agent, and water retention agent. However, the native starch paste has some shortcomings in food applications such as unstable acid and shear forces, low solubility at cold temperature and high viscosity in food system. Starch is usually modified in order to increase the applicability in food industry. Modification of starch is mainly based on chemical methods, but if improper operation, would cause chemical residues problem. The objectives of the study were to develop the modification method for corn starch and tapioca starch using non-thermal atmospheric plasma jet and to evaluate the influences of plasma on corn starch and tapioca starch in pH, thermal properties, surface specific functional groups, transparency, viscosity, and scanning electron microscopy. The process parameters of plasma treatment included electrode spacing for 2 cm, using air as working gas, air flow 15 L/min, frequency 20 kHz, plasma exposure time for 0, 1, 5 and 10 min, voltage at 140,160 and 180 V, current at 1.8, 2.1 and 2.4 A, power at 252, 336 and 432 W, respectively. The results showed that after plasma treatment, pH value of the modified corn starch and tapioca starch significantly decreased, gelatinization temperature (onset temperature, peak temperature, conclusion temperature) were significantly increased and gelatinization enthalpy was significantly decreased. The oxidation reaction occurred on the surface of the corn starch and tapioca starch granule, transparency of the modified corn starch significantly decreased, transparency of the modified tapioca starch significantly increased or decreased, viscosity of the modified corn starch and tapioca starch decreased, etching phenomena occurred on the surface of the corn starch and tapioca starch granules. The results indicated that the physical and chemical properties of corn starch and tapioca starch could be modified after plasma treatment and reduce the shortcomings of the natural starch for application in food processing.
【Key words】Non-thermal atmospheric plasma jet, Corn starch, Tapioca starch, Starch modification
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