Isomerisation kinetics and antioxidant activities of β-carotene in carrots undergoing different drying techniques and conditions

Carrots are known as a natural source of β-carotene. In order to preserve the latter, carrots must generally be processed, and drying is one of the most common methods for processing carrots. During drying β-carotene in carrots suffers degradation. β-Carotene degradation is generally due to thermal degradation and isomerisation. In this work, the drying kinetics as well as the isomerisation kinetics and antioxidant activities of β-carotene in carrots undergoing hot air drying, vacuum drying and low-pressure superheated steam drying (LPSSD) were determined within the temperature range of 60–80 °C and, in the case of vacuum drying and LPSSD, at a pressure of 7 kPa. A high performance liquid chromatography (HPLC) method was used to determine the β-carotene contents and its isomerisation kinetics, while the antioxidant activities of various combinations of all-trans- and cis-forms of β-carotene in carrots were evaluated using the Trolox equivalent antioxidant capacity (TEAC) assay.