Combined hot air convective drying and microwave-vacuum drying of blueberries (Vaccinium corymbosumL.): Drying kinetics and quality characteristics

Abstract The aim of the study was to evaluate the effect of sonication (S), microwave-vacuum (MWV), convective freezing (F), cryogenic freezing (N), and their combinations, as well as pulsed vacuum osmotic dehydration (PVOD) on the drying kinetics, bioactive compounds, texture and color of whole cranberries during combined hot air convective drying, and microwave-vacuum drying (HACD+MWVD). Drying of berries took from 20 to 493 min. Drying rate was enhanced by 23% and drying time of non-osmotically dehydrated fruits was shortened by 33% using F treatment, while MWV decreased moisture content before drying by 68% and shortened the drying time of PVOD berries by 96%. Generally, total phenolic (TP) content increased during processing, total flavonoids (TF), and total monomeric anthocyanins (TMA) contents decreased, while the values of ferric reducing antioxidant power (FRAP) of dried fruits depended on the initial pretreatment. F and HACD+MWVD yielded fruits of the highest L* (33.8 ± 0.7), a* (25.2 ± 1.0), and b* (7.3 ± 0.6), inflated oval shape, and a small amount of wrinkles on the surface. PVOD and HACD+MWVD resulted in flat and wrinkled fruits.

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Effect of Vacuum Impregnation on Drying Kinetics and Selected Quality Factors of Apple Cubes

International Journal of Food Engineering ◽

10.1515/ijfe-2016-0309 ◽

2017 ◽

Vol 13 (6) ◽

Cited By ~ 5

Author(s):

Marta Pasławska ◽

Bogdan Stępień ◽

Agnieszka Nawirska-Olszańska ◽

Radosław Maślankowski ◽

Leszek Rydzak

Keyword(s):

Sucrose Solution ◽

Drying Kinetics ◽

Convective Drying ◽

Vacuum Impregnation ◽

Vacuum Drying ◽

Quality Factors ◽

Microwave Vacuum Drying ◽

Two Component ◽

Colour Changes ◽

Anti Oxidant

AbstractThe possibility of using the vacuum impregnation as a pretreatment before drying apple cubes was investigated. The impregnation was carried out for 4.5 min with the vacuum pressure of 0.01 MPa. The sucrose solution or a mixture of sucrose and the citric acid were used as infiltration liquids. Apple cubes were dried by convective drying (CD) (at temperature of 50 and 70 °C) or microwave-vacuum drying (MVD) (at power of microwaves 120 and 480 W). The drying kinetics was determined and quality factors (anti-oxidant activity, mechanical–rheological properties and colour changes) were analysed. Studies proved that the vacuum impregnation causes increasing of the drying dynamics (12.50–28.57 % during CD and 12.50–18.48 % during MVD). All impregnated apples were darker, yellower and susceptible for deformation or cutting than non-impregnated. The highest level of anti-oxidant activity was observed when two-component impregnant before MVD by power of 480 W was used.

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Kinetics of Microwave Vacuum Drying of “Cat Chu” Mango in Mekong Delta - Vietnam

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.656-657.573 ◽

2015 ◽

Vol 656-657 ◽

pp. 573-579 ◽

Cited By ~ 1

Author(s):

Cuong Nguyen Van ◽

Hau Tran Tan

Keyword(s):

Mekong Delta ◽

Convective Drying ◽

Vacuum Drying ◽

Second Phase ◽

High Quality ◽

Hot Air Drying ◽

Drying Time ◽

Air Drying ◽

Microwave Vacuum Drying ◽

Hot Air

Microwave vacuum drying is one of innovative drying techniques that is today used in drying of foods, medical products and other high quality products. In this drying technology, heat is generated by directly transforming the electromagnetic energy into kinetic molecular energy of water, thus the heat is produced deep within the material to be dried under vacuum environment. This paper presents the results of research on microwave vacuum drying of “Cat Chu” mango in Mekong Delta – Vietnam. “Cat Chu” mango, with moisture content of (80 ± 1) % (wet basis - wb), was sliced into 5 cm thickness, and was dried in mWaveVac0150-lc dryer (Püschner - Germany). The drying vacuum was from 60 to 120 mbar. Three levels of microwave power were established: the first phase from 600 to 800 W, the second phase from 300 to 500 W, the last one from 150 to 250 W. The control sample was dried by convective drying method at 60 °C; and vacuum drying at 70 mbar, 60 °C. The results of this research showed that high quality product in terms of color, surface shrinkage and structure was obtained by microwave vacuum drying. The drying time was about 45 min, 450 min and 870 min with microwave vacuum drying, vacuum drying and convective hot-air drying, respectively. In addition, Fick’s equation and Crank’s solution were applied to analyze and calculate the accessibility and diffusion coefficient of microwave vacuum drying process. Starting accessibility of process was significantly increased; the diffusivity obtained was within a range from 6.44*10-10 m2/s to 16.16*10-10 m2/s. The results also indicated that there was a higher exchange in surface and a greater internal diffusion of experimental microwave vacuum drying samples compared to the control vacuum and hot-air drying samples.

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The effect of freezing on the hot air and microwave vacuum drying kinetics and texture of whole cranberries

Drying Technology ◽

10.1080/07373937.2018.1543317 ◽

2019 ◽

Vol 37 (13) ◽

pp. 1714-1730 ◽

Cited By ~ 9

Author(s):

Magdalena Zielinska ◽

Marek Markowski ◽

Danuta Zielinska

Keyword(s):

Drying Kinetics ◽

Vacuum Drying ◽

Microwave Vacuum Drying ◽

Hot Air

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Evaluation of ultrasound‐assisted microwave hot air convective drying Chinese hickory—Drying kinetics and product's quality properties

Journal of Food Process Engineering ◽

10.1111/jfpe.13842 ◽

2021 ◽

Author(s):

Jigang Zhang ◽

Maoye Li ◽

Zhien Ding ◽

Chuyan Wang ◽

Jianghua Cheng

Keyword(s):

Drying Kinetics ◽

Convective Drying ◽

Quality Properties ◽

Hot Air ◽

Ultrasound Assisted

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Investigation of ultrasound-assisted convective drying process on quality characteristics and drying kinetics of zucchini slices

Heat and Mass Transfer ◽

10.1007/s00231-019-02573-6 ◽

2019 ◽

Vol 55 (8) ◽

pp. 2153-2163 ◽

Cited By ~ 3

Author(s):

Niloufar Bagheri ◽

Somayeh Taghian Dinani

Keyword(s):

Quality Characteristics ◽

Drying Kinetics ◽

Convective Drying ◽

Drying Process ◽

Ultrasound Assisted ◽

Kinetics Of

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Effect of Drying Methods on Physicochemical Parameters of Different Red Beetroots (Beta vulgaris L.) Species

Periodica Polytechnica Chemical Engineering ◽

10.3311/ppch.13104 ◽

2019 ◽

Author(s):

Dóra Székely ◽

Klaudia Vidák ◽

Diána Furulyás ◽

Ákos Ribárszki ◽

Mónika Stéger-Máté

Keyword(s):

Physicochemical Parameters ◽

Color Change ◽

Vacuum Drying ◽

Drying Methods ◽

Total Polyphenol ◽

Microwave Vacuum Drying ◽

Hot Air ◽

Vacuum Method ◽

Drying Technology

The aim of this work was to study the influence of atmospheric, vacuum and microwave vacuum drying methods on the quality of dried beetroots. Three different red beetroot species ('Alto F1', 'Cylindra', 'Detroit') were chosen in this study. The microwave vacuum method reduced the total time of drying and decreased the shrinkage compared to the other drying methods. The quality of the dehydrated material was described by its color change, antioxidant capacity, total polyphenol, betacyanin, betaxanthin and each phenolic acids content. The attempts were made to suggest the microwave vacuum method for red beetroot samples as a gentle drying technology to reach a special texture that is favoured by costumers. During the experiments relevant differences could be observed between the investigated beetroot species on the effect of different drying methods. According to the examined parameters the 'Cylindra' species proved the most appropriate beetroot variety for microwave vacuum drying. Based on the results, the combined methods with hot-air at 60 °C followed by microwave vacuum finish drying was the most suitable assay to preserve the investigated parameters in the highest amount.

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