Effects of drying methods on the composition of thyme (Thymus vulgaris L.) essential oil
Ángel Calín-Sánchez , Adam Figiel , Krzysztof Lech , Antoni Szumny , Ángel A. Carbonell-Barrachina
AbstractThe influence of drying method on aroma compounds of thyme (Thymus vulgaris L.) was evaluated. The drying methods tested were convective drying, vacuum-microwave drying, and freeze drying, as well as a combination of convective predrying and VM finish drying. Thyme's convective drying kinetics are described by a two-term exponential model, and VM drying kinetics consisted of two periods: a constant rate period until a critical moisture ratio (values of 0.311, 0.242, and 0.162 kg kg-1 for 240, 360, and 480 W, respectively) was obtained and a falling rate period beyond that point. Volatile compounds of thyme samples were extracted by hydrodistillation and analyzed by gas chromatography. Thirty-three compounds were tentatively identified; thymol, γ-terpinene, p-cymene, caryophyllene, and α-terpinene were the major components. The total quantity of volatiles of fresh thyme (1,167 mg 100 g-1 db) was reduced by most of the drying treatments, with the exception of VM at 240 and 360 W. The combined method with 40°C and 240 W was the best option for drying thyme; the time required was relatively short (≈ 301 min) and aroma quality was good according to instrumental data (total concentration of volatiles 1,127 mg 100 g-1 db) and sensory evaluation results (high scores for fresh thyme and vegetable odors). © 2013 Copyright Taylor and Francis Group, LLC.
|Journal series||Drying Technology, ISSN 0737-3937, (A 35 pkt)|
|Publication size in sheets||0.55|
|Keywords in English||Aromatic herbs; Essential oils; Food drying; Hot air drying; Thymol; Vacuum–microwave drying|
|Score|| = 35.0, 10-09-2020, ArticleFromJournal|
= 35.0, 10-09-2020, ArticleFromJournal
|Publication indicators||= 40; = 44; : 2013 = 1.125; : 2013 = 1.742 (2) - 2013=1.737 (5)|
|Citation count*||62 (2020-09-15)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.