Moderate electric field-assisted hydro-distillation of thyme essential oil: Characterization of microstructural changes

Novel technologies are applied to improve the hydro-distillation process in the production of essential oils of commercial importance. In this study, it was aimed to examine the effect of the moderate electric field-assisted hydro-distillation (MEF-D) method, which was applied at different frequencies and wave type conditions, on the microstructural changes of thyme samples. Microscopic images of the samples were taken before and after MEF-D treatments. The perimeter and area of peltate and capitate cells in leaves and stems were measured, and the percentage of damage to secretory cells was determined. The results were compared with the conventional hydro-distillation method. The correlation analysis was performed for the relations between different responses; image analysis results, the cell disintegration index (Zc), and essential oil yields after MEF-D treatments. The highest oil yield (52.2 +/- 4.02) was obtained with MEF-D square wave type at 1,000 Hz condition (p 0.05). Glandular trichomes were damaged in all conditions (p 0.05). Damaged Glandular Trichomes (DGT) values were higher for MEF-D square wave conditions compared to the sine wave (p 0.05). The highest Zc values (0.80 +/- 0.02 for sine wave type and 0.78 +/- 0.03 for square wave type) were obtained for 1,000 Hz frequency application in both wave types. Good correlations (Pearson correlation coefficient > 0.995) between image analysis parameters and Zc were obtained. MEF-D method increased the anatomical changes, and thus resulted in a higher yield of essential oil. It is expected that the results of the study will contribute to the improvement of hyro-distillation processes.This study is a part of a project titled Investigation of Effects of Moderate Electric Field Application in Food Processing on the Changes of Plant and Animal Tissues' and is financially supported by TUEBITAK (THE SCIENTIFIC AND TECHNOLOGICAL RESEARCH COUNCIL OF TUERKIYE) Project No. 119O768. The authors gratefully acknowledge TUEBITAK for financial support.TUEBITAK (THE SCIENTIFIC AND TECHNOLOGICAL RESEARCH COUNCIL OF TUERKIYE) [119O768

Degradation kinetics of bioactive compounds and antioxidant capacity of Brussels sprouts during microwave processing

WOS: 000427943700041In this study, the effects of microwave (MW) processing of Brussels sprouts on various bioactive compounds, moisture content, and antioxidant capacity were studied. Brussels sprouts was processed at three different MW output powers (460, 600, and 700W), and then kinetic study for the degradation of the total chlorophyll, vitamin C, total polyphenols, total flavonoids, antioxidant capacity, and two phenolic acids (sinapic and ferulic acid) was conducted. According to the results, MW processing caused significant reductions in analyzed bioactive compounds, moisture content, and antioxidant capacity. It was found that HPLC analysis results confirmed the result of the spectroscopic analysis. Zero-order and first-order kinetic models were fitted to experimental data. The first-order kinetic model was selected as the best according to R-2, RMSE, and (2). The degradation rate constant (k) for all analyzed properties increased as the MW output power increased from 460 to 700W, and it could be concluded that the MW output power in which bioactive compounds, moisture content, and antioxidant capacity of Brussels sprouts were best preserved was 460W