Scientific journal

63 2024

Journal of Food and Nutrition Research
Summary No. 1 / 2024

Sinthukot, M. – Suanjan, S. – Chupawa, P. – Inchuen, S. – Ronsse, F. – Duangkhamchan, W.
Drying characteristics and quality attributes of quick-cooking Job’s tears as affected by rotary drying combined with microwave heating
Journal of Food and Nutrition Research, 63, 2024, No. 1, s. 37-51

Wasan Duangkhamchan, Research Unit of Smart Process Design and Automation, Faculty of Engineering, Mahasarakham University, Kamriang, Kantarawichai, Maha Sarakham 44150, Thailand; Research Unit of Process Design and Automation, Faculty of Engineering, Mahasarakham University, Kamriang, Kantarawichai, Maha Sarakham 44150, Thailand. E-mail: wasan.d@msu.ac.th

Original article
Received 27 June 2023; 1st revised 21 July 2023; 2nd revised 3 August 2023; 3rd revised 19 September 2023; accepted 2 October 2023; published online 2 February 2024.

Summary: A combined microwave heating and rotary drying process was developed to prepare the quick-cooking Job‘s tears. Using operating parameters of hot air temperature (70–90 °C), microwave power (150–450 W) and rotational drum speed (0.17–0.50 s-1), drying characteristics were described using the Page drying model. The model parameters (drying rate constant k and power constant n) considerably correlated with drying factors using the quadratic equation. Drying time (DT) predicted by the Page model and effective diffusivity coefficient (De) ranged from 42 min to 116 min and from 487.69 × 10-8 m2·s-1 to 1 249.96 × 10-8 m2·s-1, respectively. The proposed drying technique resulted in lower DT and higher De, while utilizing less energy than hot air drying. Response surface methodology showed the influence of all operating factors on drying rate constant (k), DT, De, and specific energy consumption (SEC). Optimal drying conditions were determined by maximizing k and De while minimizing DT and SEC as air temperature of 76 °C with 450 W microwave heating and 0.17 s-1 rotational drum speed. Quality attributes of quick-cooking Job’s tears prepared by drying under such optimal conditions were comparable to those prepared by conventional cooking and freeze-drying. Findings of this study can be used for practical application of Job’s tears grains.

Keywords: adlay; rotary drying; drying model; microwave heating; quick-cooking grain; response surface

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