Blackwell Publishing Journal Backfiles 1879-2005
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Process Engineering, Biotechnology, Nutrition Technology
SUMMARY —Small white potatoes were heated with microwave energy followed by boiling water to determine the penetration of heat, inactivation of peroxidase and firmness of the potatoes. Treatments consisted of heating potatoes with microwave energy for 0.5, 1, 1.5 and 2 min followed by boiling water for 0, 1, 2, 3, 4 and 5 min. Temperature measurements were made at depths of 0.75 and 1.5 cm using tubers with a mean radius of 1.95 cm. Peroxidase inactivation was measured along the radius of a slice removed from the equatorial region. Firmness was determined by the ALLO-Kramer shear press. Potatoes, when heated by microwave energy, became hot first at the core with a heat gradient developing toward the periphery. Boiling water produced a heat gradient from the periphery toward the core. Consequently, the tissue located about midway of the radius was subjected to the least amount of heat. The minimum time required to completely inactivate peroxidase and the firmness values of the potato tissue at the time of enzymatic inactivation were as follows: 1.5 min microwaves and 3 min boiling water, 119 lb shear force; and 2 min microwaves and 2 min boiling water, 124 lb shear force. Peroxidase was not completely destroyed when the potatoes were subjected to energy for 1 min or less followed by heating in boiling water up to 5 min.
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