บุษวรรณ หิรัญวรชาติ. Determination of Isomerization Kinetics and Antioxidant Activities of B-Carotene in Carrots Undergoing Different Drying Techniques and Conditions. Master's Degree(Food Engineering). King Mongkut's University of Technology Thonburi. : King Mongkut's University of Technology Thonburi, 2006.
Determination of Isomerization Kinetics and Antioxidant Activities of B-Carotene in Carrots Undergoing Different Drying Techniques and Conditions
Abstract:
The present research aimed at studying the isomerization kinetics and antioxidant activities of carrots undergoing different drying techniques and conditions. In the first part a study of the isomerization
kinetics of B-carotene in carrots undergoing hot air drying, vacuum drying and low-pressure superheated steam drying (LPSSD) at the temperatures of 60, 70 and 80 ํC and at the absolute pressure of
7 kPa in the cases of vacuum drying and LPSSD was conducted. High-Performance Liquid Chromatography (HPLC) method was used to determine the B-carotene contents and its isomerization
kinetics. It was found that LPSSD could better preserve B-carotene, at the final moisture content of 0.1 kg/kg (d.b.), than could vacuum drying and hot air drying; the losses of B-carotene at the final
moisture content of 0.1 kg/kg (d.b.) were 72, 68 and 65% in the cases of hot air drying, vacuum drying and LPSSD, respectively. Furthermore, 13-cis-B-carotene was found to be a predominant cis
isomer in all cases. 13-cis-B-carotene started to form at the moisture contents lower than 0.5, 2.2 and 6.3 kg/kg (d.b.) in the cases of vacuum drying, hot air drying and LPSSD, respectively. However,
the total amounts of 13-cis-B-carotene at various conditions were not much different.
In the second part of the study the antioxidant activities of various combinations (or proportions) of all-trans and cis forms of B-carotene in carrots were evaluated using the TEAC (Trolox Equivalent
Antioxidant Capacity) assay. The antioxidant activities were reported in terms of % relative inhibition. Hot air drying led to products with lower antioxidant activities at the final moisture content of 0.1
kg/kg (d.b.) than in the cases of vacuum drying and LPSSD. At the final moisture content of 0.1 kg/kg (d.b.), the losses in the % relative inhibition were about 70, 60 and 55% in the cases of hot air dying,
vacuum drying and LPSSD, respectively. These results corresponded to the results of the isomerization kinetics of ?-carotene, in which LPSSD and vacuum drying were shown to better preserve
B-carotene than did hot air drying by partially converting all-trans-B-carotene into 13-cis-B-carotene.