Numerical analysis of heat and mass transfers during intermittent microwave drying of Chinese jujube (Zizyphus jujuba Miller)

Hou, Lixia; Li, Rui; Wang, Shaojin; Datta, Ashim K.

doi:10.1016/j.fbp.2021.06.005

Cited by 21 publications

(5 citation statements)

References 35 publications

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“…This indicates that in the preliminary period of microwave drying, water molecules in corn vibrate rapidly under the action of microwaves, resulting in the generation of frictional heat. The internal temperatures of the samples increase rapidly, and a temperature gradient between the air in the drying chamber and samples is generated, which encourages moisture inside the corn to spread outwards [27][28][29][30]. Hence, the more powerful the microwave irradiation, the faster the drying process.…”

Section: Effects Of Microwave Power On Drying Characteristics Of Cornmentioning

confidence: 99%

Microwave Drying Characteristics and Drying Quality Analysis of Corn in China

Liu

et al. 2021

Processes

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To identify the microwave drying characteristics of corn, microwave drying tests were conducted on corn. By taking the moisture content, drying rate, and drying temperature as indices, this research revealed the effects of different microwave powers and loads on the microwave drying characteristics of corn. Moreover, energy consumption and quality of dried corn were analysed under different drying conditions. The results demonstrate that microwave drying has significant energy-saving effects. The energy consumption by microwave drying is less than 0.3 times that used by electrothermal drying under the same load. Both microwave power and load exert significant influences on drying characteristics. Higher microwave power results in a greater average drying rate, wherein shorter periods of time are required to reach the maximum drying rate and higher temperatures of the corn. However, the load shows the opposite tendency. The smaller the load, the higher the temperature of the corn in the early stage of drying. However, as drying continues, the temperature curve changes significantly, and the temperature rises with the increase in load in the later stage of drying. In consideration of energy consumption and dried quality, the load of corn should be increased as appropriate, and the microwave intensity should be limited to no higher than 0.7 W/g in the experiment.

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Section: Effects Of Microwave Power On Drying Characteristics Of Cornmentioning

confidence: 99%

Microwave Drying Characteristics and Drying Quality Analysis of Corn in China

Liu

et al. 2021

Processes

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“…Microwaves increase moisture evaporation rates from plant tissues by the rapid activation of energy absorption of water molecules. This leads to the generation of a temperature gradient between the sample and the air in the drying chamber that promotes the moisture in the samples to move outwards (Hemis et al, 2011;Doymaz et al, 2015;Hou et al, 2021;Mouhoubi et al, 2022). Previous reports of the Trabzon persimmon fruit (Alibas et al, 2019) and Kaffir lime leaf (Pradechboon et al, 2022) showed that increases in MD power induced a rapid increase in temperature due to the high energy transfer into samples.…”

Section: Discussionmentioning

confidence: 99%

Quality and bioactive compound accumulation in two holy basil cultivars as affected by microwave-assisted hot air drying at an industrial scale

Wiset,

Poomsa-ad,

Jindamol

et al. 2023

Front. Sustain. Food Syst.

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Holy basil (Ocimum Tenuiflorum L.) contains several bioactive compounds useful to the pharmaceutical and food industries. Microwave drying (MD) is a powerful technique for rapid drying of food or plant materials while preserving bioactive compounds during the process. However, little is known about the optimal combination of MD power with hot air drying (HAD) that can preserve the quality and yet only consume reasonable energy when drying holy basils. For that purpose, the effects of drying methods using MD combined with HAD at 45°C were examined to prevent losses in quality, antioxidant activities, and volatile flavor compounds in two holy basil cultivars (green and red cultivars). Holy basil leaves were dried at different MD powers of 200, 400, and 600 W combined with HAD and compared with a traditional tray drying (TD) at 45°C. Drying using MD at 600 W with HAD displayed significantly high levels of color retention, chlorophyll, and carotenoid content in both cultivars. The green cultivar showed a greater accumulation of total phenolic compounds (TPC), terpenoids, and DPPH free radical scavenging at 400 W with HAD. However, the red cultivar had the highest TPC, flavonoid, and terpenoid content at 600 W with HAD. The accumulation of major volatile organic compounds (VOCs) was also affected, and treatment at 600 W exhibited the highest methyl eugenol and β-caryophyllene content in both cultivars. The use of the highest power of MD (600 W) with HAD for leaf drying reduced the effective drying time and energy consumption among both cultivars. Taking into consideration the dried quality of antioxidant accumulation and energy consumed for drying, we recommend using MD at 400 or 600 W with HAD for the green cultivar and 600 W for the red.

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“…Microwave drying is fast and efficient; however, it is easy to cause scorching of materials and thus affect the quality of products. [15][16][17][18] Huang et al 19 investigated the microwave intermittent drying characteristics of C. oleifera seeds. They found that the drying time of C. oleifera seeds under microwave intermittent drying was more than four times shorter than that under hot air drying.…”

Section: Introductionmentioning

confidence: 99%

“…Microwave drying is fast and efficient; however, it is easy to cause scorching of materials and thus affect the quality of products. 15–18 Huang et al 19 investigated the microwave intermittent drying characteristics of C . oleifera seeds.…”

Section: Introductionmentioning

confidence: 99%

Optimization of variable-temperature drying of Camellia oleifera seeds

Men

Huang

Qin

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part E:

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The processing method of Camellia oleifera fruit used in the industry was investigated, that is, fresh C. oleifera fruit was shelled in the drying equipment first and then the remaining C. oleifera seeds returned until the target moisture content (about 10% d.b.) was reached. The variable-temperature drying of C. oleifera seeds was investigated for the first time and the drying process was optimized and compared with constant-temperature drying. Two independent variables, including hot air drying temperature and air velocity, were studied by central composite design. The responses were drying time and quality of Camellia oil, including acid value and peroxide value. Results showed that the optimal constant-temperature drying conditions were drying at a temperature of 60.5°C and air velocity of 2.1 m/s. Under this condition, the total drying time was 607 min, and the acid and peroxide values were 1.72 mg/g and 0.12 g/100 g, respectively. The optimal variable-temperature drying conditions were drying at a constant air velocity of 2 m/s and a drying temperature of 55°C for 67 min, then 60°C for 213 min, and finally 65°C for 297 min. Under these conditions, the acid value was 1.75 mg/g and the peroxide value was 0.1 g/100 g. The optimal variable-temperature drying efficiency was 16.7% higher than that of constant-temperature drying when the optimization objective of drying time, acid value and peroxide value was 2:1:1.

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Numerical analysis of heat and mass transfers during intermittent microwave drying of Chinese jujube (Zizyphus jujuba Miller)

Cited by 21 publications

References 35 publications

Microwave Drying Characteristics and Drying Quality Analysis of Corn in China

Microwave Drying Characteristics and Drying Quality Analysis of Corn in China

Quality and bioactive compound accumulation in two holy basil cultivars as affected by microwave-assisted hot air drying at an industrial scale

Optimization of variable-temperature drying of Camellia oleifera seeds

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