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Title: THERMAL AND PASTING PROPERTIES OF MICROWAVED CORN STARCH

Author
item Stevenson, David
item Biswas, Atanu
item Inglett, George

Submitted to: Starch/Starke
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2005
Publication Date: 11/4/2005
Citation: Stevenson, D.G., Biswas, A., Inglett, G.E. 2005. Thermal and pasting properties of microwaved corn starch. Starch/Starke. 57:347-353.

Interpretive Summary: The modification of low-moisture corn starch at low microwave power was studied using a sophisticated microwave that can accurately control starch temperature and microwave power. Low microwave power elevated the temperature that corn starch melts and forms a paste; and decreased starch paste viscosity, but clumping and peeled layers occurred. Impact of study highlighted that although starch functional properties were modified by low-power microwaving; further research needs to focus, due to clumping, on high-moisture starch at high microwave power for short times to modify starch for industry utilization.

Technical Abstract: Corn starch with 15-40% moisture was irradiated at 0.17 or 0.5 W/g for 1 h using the sophisticated Ethos 1600 microwave that accurately controls temperature and wattage. Temperature of irradiated starch was measured during microwaving. Thermal and pasting properties were studied on dehydrated starch after microwave irradiation. Temperature increases were greatest in first 10 min for starch at all moisture contents at both microwave power levels. Starch irradiated at 0.17 W/g had a temperature below onset gelatinization temperature after 1 h. Higher temperatures were observed for starch with higher moisture content and microwaved at 0.5 W/g. Compared to native starch, starch with 15-40% moisture had higher gelatinization temperature (measured using differential scanning calorimetry) and 35-40% moisture had higher peak gelatinization temperature and lower enthalpy change of gelatinization. All paste viscosity parameters measured by Rapid ViscoAnalyser were reduced and pasting temperature was elevated for starch irradiated at 0.5 W/g compared to native starch.