University of Khartoum

Levels and Thermostability of Peroxidase Extracted From Some Vegetables

Levels and Thermostability of Peroxidase Extracted From Some Vegetables

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Title: Levels and Thermostability of Peroxidase Extracted From Some Vegetables
Author: Osman, Suha Osman Ahmed
Abstract: This study aimed to extract peroxidase enzyme from some vegetables and subsequency to study its heat stability under various conditions. Unspecified varieties of potato, carrot, eggplant and tomato were selected as enzyme sources. Peroxidase was found in all vegetables investigated at different levels. Peroxidase enzyme with reasonable enzymic activity was extracted and detected at various pH values namely 5.0, 6.0, 7.0 and 8.0. Relatively higher levels of peroxidase activities were extracted at pH 5.0 from potato and tomato while those with higher levels from carrot and eggplant were extracted at pH 6.0. Potato tuber was shown to contain the highest level of peroxidase at all pH values investigated, whereas carrot had the lowest peroxidase levels at the same pH values. Soluble peroxidases extracted from the four vegetables were subjected to thermal inactivation at 60, 70, 80 and 90ºC, and varying duration of heating times 2, 4, 6, 8 and 10min under different values of pH 5.0, 6.0, 7.0 and 8.0. The results showed that the rate of loss of peroxidase activity from the four vegetables investigated increased with both increase in temperature and heating time. Biphasic inactivation curves were observed for the enzymes extracted from all samples, where the initial heat inactivation is rapid followed by a much slower inactivation periods. The patterns of inactivation of peroxidases extracted from the four vegetables were similar. The rate of loss of peroxidase activity was shown to be pH dependant. Potato peroxidase was observed to be more stable to heat as it was not completely inactivated at all tried conditions. A less severe heat treatment is required to inactivate carrot, eggplant and tomato peroxidases. Complete inactivation of carrot peroxidase was accomplished in 4–10 min at 80ºC and in 2–10 min at 90ºC, while peroxidase inactivation in eggplant required 8 – 10 min at 90ºC, both at pH 8.0. Complete inactivation of tomato peroxidase required 6 – 10 min at 90º C and pH 6.0.
Description: November 200576page
URI: http://khartoumspace.uofk.edu/handle/123456789/11077
Date: 2015-05-19


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