Oven,Temperature-Controlled Microwave,and Shade Drying Effects on Drying Kinetics,Bioactive Compounds and Antioxidant Activity of Knotweed (Polygonum cognatum Meissn.) |
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| Authors: | Samet Kaya Dursun Burcu Aksüt Osman Nuri Öcalan Muhammed Ta?ova |
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| Institution: | 1. Tokat Gaziosmanpa?a University, Faculty of Agriculture, Department of Biosystems Engineering, 60250 Tokat/, Turkey;2. Tokat Gaziosmanpa?a University, Agricultural Faculty, Horticulture Department, Sustainable Agriculture Program, 60250 Tokat/, Türkiye;3. Tokat Gaziosmanpa?a University, Faculty of Agriculture, Department of Horticulture, 60250 Tokat/, Turkey |
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| Abstract: | In this study, the plant node was dried in an oven (40, 50 and 60 °C), shade and temperature-controlled microwave (40, 50 and 60 °C) methods. Statistically (p<0.05), the values closest to the color values of fresh grass were determined in an oven at 40 °C drying temperature. Effective diffusion values varied between 8.85×10?8–5.65×10?6 m2 s?1. While the activation energy was 61.28 kJ mol?1 in the oven, it was calculated as 85.24 kJ mol?1 in the temperature-controlled microwave. Drying data was best estimated in the Midilli-Küçük (R2 0.9998) model oven at 50 °C. The highest SMER value was calculated as 0.0098 kg kWh?1 in the temperature-controlled microwave drying method. The lowest SEC value in the temperature-controlled microwave was determined as 24.03 kWh kg?1. It was determined that enthalpy values varied between ?2484.66/?2623.38 kJ mol?1, entropy values between ?162.04/?122.65 J mol?1 and Gibbs free energy values between 453335.22–362581.40 kJ mol?1. Drying rate values were calculated in the range of 0.0127–0.9820 g moisture g dry matter?1 in the temperature-controlled microwave, 0.0003–0.0762 g dry matter?1 in the oven, and 0.001–0.0058 g moisture g dry moisture matter?1 in the shade. Phenolic content 6957.79 μg GAE g?1 fw - 48322.27 μg GAE g?1 dw, flavonoid content 3806.67 mg KE L?1 fw - 22200.00 mg KE L?1 dw and antioxidant capacity 43.35 μmol TE g?1 fw - 323.47 μmol TE g?1 dw. The highest chlorophyll values were obtained from samples dried in an oven at 40 °C. According to the findings, it is recommended to dry the knotweed (Polygonum cognatum Meissn.) plant in a temperature-controlled microwave oven at low temperatures. In this study, in terms of drying kinetics and energy parameters, a temperature-controlled microwave dryer of 60 °C is recommended, while in terms of quality characteristics, oven 40 °C and shade methods are recommended. |
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| Keywords: | drying processes drying kinetic energy analyses quality properties |
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