Thermal Characteristics of Ohmically Heated Rice Starch and Rice Flours

Thermal properties of conventionally and ohmically heated rice starch and rice flours at various frequencies and voltages were studied. There was an increase in gelatinization temperature for conventionally heated rice starches since they were pregelatinized and became more rigid due to starch-chain...

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Bibliographic Details
Published in:Journal of food science 2007, Vol.72 (1), p.C084-C088
Main Authors: An, H.J, King, J.M
Format: Article
Language:English
Subjects:
Biological and medical sciences
Calorimetry, Differential Scanning
Carbohydrates
Cereal and baking product industries
Chemical Phenomena
Chemistry, Physical
DSC
enthalpy
Flour - analysis
Food Handling - methods
Food industries
Fundamental and applied biological sciences. Psychology
gelatinization
Gels
Hot Temperature
lipid content
Lipids
ohmic heating
Oryza - chemistry
protein content
Rice
rice flour
rice starch
Starch - chemistry
Starch and starchy product industries
Studies
thermal stability
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Summary:Thermal properties of conventionally and ohmically heated rice starch and rice flours at various frequencies and voltages were studied. There was an increase in gelatinization temperature for conventionally heated rice starches since they were pregelatinized and became more rigid due to starch-chain interactions. In addition, there was a decrease in enthalpy (energy needed) for conventionally and ohmically heated starches during gelatinization; thus, the samples required less energy for gelatinization during DSC analysis. Ohmically heated commercial starch showed the greatest decrease in enthalpy probably because of the greatest extent of pregelatinization through ohmic heating. Brown rice flour showed the greatest gelatinization temperature resulting from the delay of starch granule swelling by lipid and protein. Enthalpy of ohmically heated starches at 20 V/cm was the lowest, which was most likely due to the lower voltage resulting in a more complete pregelatinization from a longer heating time required to reach 100 °C. Ohmic treatment at 70 V/cm decreased onset gelatinization temperature of white flour; therefore, it produced rice flour that swelled faster, whereas the conventionally heated sample showed a better thermal resistance.
ISSN:0022-1147
1750-3841
DOI:10.1111/j.1750-3841.2006.00239.x