scholarly journals Combined Hot Air and Microwave-Vacuum Drying of Cranberries: Effects of Pretreatments and Pulsed Vacuum Osmotic Dehydration on Drying Kinetics and Physicochemical Properties

2020 ◽  
Vol 13 (10) ◽  
pp. 1848-1856
Author(s):  
Zi-Liang Liu ◽  
Izabela Staniszewska ◽  
Danuta Zielinska ◽  
Yu-Hao Zhou ◽  
Konrad W. Nowak ◽  
...  
Keyword(s):  
Osmotic Dehydration ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Total Phenolic ◽  
Vacuum Drying ◽  
Drying Time ◽  
Antioxidant Power ◽  
Microwave Vacuum Drying ◽  
Hot Air ◽  
Ferric Reducing Antioxidant Power

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.

scholarly journals Drying of Phyla nodiflora Leaves: Antioxidant Activity, Volatile and Phytosterol Content, Energy Consumption, and Quality Studies

Processes ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 210 ◽  
Author(s):  
Lisa Yen Wen Chua ◽  
Bee Lin Chua ◽  
Adam Figiel ◽  
Chien Hwa Chong ◽  
Aneta Wojdyło ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Energy Consumption ◽  
Drying Kinetics ◽  
Microwave Drying ◽  
Convective Drying ◽  
Total Phenolic ◽  
Drying Methods ◽  
Drying Time ◽  
Antioxidant Power ◽  
Vacuum Microwave

Drying is an important process in the preservation of antioxidants in medicinal plants. In this study, leaves of Phyla nodiflora, or commonly known as frog fruit, were dried using convective drying (CD) at 40, 50, and 60 °C; vacuum-microwave drying (VMD) at 6, 9, and 12 W/g; and convective pre-drying followed by vacuum-microwave finish drying (CPD–VMFD) at 50 °C and 9 W/g. Drying kinetics of P. nodiflora leaves was modelled, and the influences of drying methods on the antioxidant activity, total phenolic content, volatile and phytosterol contents, energy consumption, water activity, and color properties were determined. Results showed that drying kinetics was best described by modified Page model. VMD achieved highest drying rate, whereas VMFD considerably reduced the drying time of CD from 240 min to 105 min. CPD–VMFD was the best option to dry P. nodiflora in terms of retaining volatiles and phytosterols, with lower energy consumption than CD. Meanwhile, VMD at 6 W/g produced samples with the highest antioxidant activity with 2,2′-Azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and ferric reducing antioxidant power (FRAP) value of 11.00 and 15.99 µM Trolox/100 g dw, respectively.

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

2015 ◽  
Vol 656-657 ◽  
pp. 573-579 ◽  
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.

scholarly journals Drying of ‘yacon’ pretreated by pulsed vacuum osmotic dehydration

2021 ◽  
Vol 25 (8) ◽  
pp. 560-565
Author(s):  
Letícia F. Oliveira ◽  
Jefferson L. G. Corrêa ◽  
Paula G. Silveira ◽  
Marina B. Vilela ◽  
João R. de J. Junqueira
Keyword(s):  
Water Activity ◽  
Osmotic Dehydration ◽  
Drying Kinetics ◽  
The Other ◽  
Convective Drying ◽  
Vacuum Drying ◽  
Second Law ◽  
Drying Time ◽  
Different Temperatures

ABSTRACT In this study, the ‘yacon’ was dried using pulsed vacuum osmotic dehydration as pretreatment followed by vacuum drying (at different temperatures) or convective drying. The use of osmotic dehydration and vacuum drying had their influence evaluated concerning drying kinetics and quality of the final product, considering fructan retention, color, and water activity. Fick’s second law and Page’s equation were suitable for the fitting of drying evolution. It was observed that higher temperatures (60 °C) resulted in shorter drying time, higher diffusivity, and higher fructan retention when compared to 40 and 50 °C. The osmotic pretreatment and the vacuum drying differed in fructan retention (p ≤ 0.05). Moreover, the dried product, osmotically pretreated, presented a shorter drying time. The best condition was vacuum drying at 60 ºC, preceded by pulsed vacuum osmotic dehydration that resulted in fructan retention of approximately 38% in a quicker, higher diffusivity and lighter color product concerning the other tested conditions.

scholarly journals Optimization of Microwave Vacuum Drying and Pretreatment Methods for Polygonum cuspidatum

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Wanxiu Xu ◽  
Guanyu Zhu ◽  
Chunfang Song ◽  
Shaogang Hu ◽  
Zhenfeng Li
Keyword(s):  
Mathematical Models ◽  
Scale Up ◽  
Drying Kinetics ◽  
Vacuum Drying ◽  
Orthogonal Experimental Design ◽  
Polygonum Cuspidatum ◽  
Drying Time ◽  
Microwave Vacuum Drying ◽  
Thin Layer Drying ◽  
Drying System

This study was conducted to optimize the drying process of Polygonum cuspidatum slices using an orthogonal experimental design. The combined effects of pretreatment methods, vacuum pressure and temperature of inner material, drying kinetics, color value, and retention of the indicator compounds were investigated. Seven mathematical models on thin-layer drying were used to study and analyze the drying kinetics. Pretreatment method with blanching for 30 s at 100°C increased the intensity of the red color of P. cuspidatum slices compared with other pretreatment methods and fresh P. cuspidatum slices. P. cuspidatum slices dried at 60°C retained more indicator compounds. Furthermore, microwave pretreatment methods, followed by microwave vacuum for 200 mbar at 50°C, resulted in high concentration of indicator compounds, with short drying time and less energy. This optimized condition for microwave vacuum drying and pretreatment methods would be useful for processing P. cuspidatum. The Newton, Page, and Wang and Singh models slightly fitted the microwave vacuum drying system. The logarithmic, Henderson and Pabis, two-term, and Midilli et al. models can be used to scale up the microwave vacuum drying system to a commercial scale. The two-term and Midilli et al. models were the best fitting mathematical models for the no-pretreatment case at 600 mbar and 60°C.

scholarly journals Influence of preliminary osmotic dehydration on drying kinetics and final quality of carrot (Daucus carota L.)

2011 ◽  
Vol 32 (3) ◽  
pp. 185-194 ◽  
Author(s):  
Stefan Kowalski ◽  
Dominik Mierzwa
Keyword(s):  
Daucus Carota ◽  
Osmotic Dehydration ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Drying Time ◽  
Solid Gain ◽  
Visual Appearance ◽  
Daucus Carota L ◽  
Colorimetric Measurements

Influence of preliminary osmotic dehydration on drying kinetics and final quality of carrot (Daucus carotaL.)This paper concerns convective drying of carrot preliminary dehydrated in aqueous solutions of three types of osmotic agents (sucrose, fructose, glucose). Three solution concentrations (20, 40 and 60%) were examined to work out efficient conditions of osmotic dewatering. The parameters such as water loss (WL), solid gain (SG) and osmotic drying rate (ODR) indicating the real efficiency of osmotic dehydrations (OD) were determined. The samples dehydrated with osmotic solutions underwent further convective drying to analyze influence of dehydration process on drying kinetics and final products quality. The quality of products was assessed on the basis of visual appearance of the samples and colorimetric measurements. It was found that osmotic pretreatment improves significantly the final product quality as the samples were less deformed and their colour was better preserved compared to samples, which had not been preliminarily dehydrated. Preliminary dehydration, however, did not influence significantly the overall drying time of the samples.

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

2017 ◽  
Vol 13 (6) ◽  
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.

The Impact of the Pre-Treatment in Ethanol Solution on the Drying Kinetics and Selected Properties of Convective Dried Apples

2019 ◽  
Vol 16 (1-2) ◽  
Author(s):  
Joanna Zubernik ◽  
Magdalena Dadan ◽  
Joanna Cichowska ◽  
Dorota Witrowa-Rajchert
Keyword(s):  
Ethanol Solution ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Total Phenolic ◽  
Prolonged Storage ◽  
Drying Time ◽  
Pre Treatment ◽  
The One ◽  
The Impact

AbstractThe aim of this study was to investigate the effects of pre-treatment in ethanol solution carried out in variable time with and without ultrasound (US) assistance on convective drying kinetics, total phenolic content (TPC) and hygroscopicity of an apple. The drying time after immersion in ethanol solution was shorter up to 13.4 (without US) and 18.3 % (with US) in comparison to intact slices. The most appropriate model that described kinetics of drying was the one proposed by Sledz et al. Drying of the untreated apple resulted in a decrease of the TPC by 18 %, compared with raw apples and the pre-treatment led to further losses. The tissue after ethanol pre-treatment was less hygroscopic, which proves the possibility to maintain a characteristic texture of the dried apple with prolonged storage stability. The best quality of dried apples was obtained after 1 min of ethanolic pre-treatment with US.

The Influence of Selected Drying Methods on the Physical Properties of Dried Apples cv. Jonagold Grown in Different Locations in Europe

2017 ◽  
Vol 13 (6) ◽  
Author(s):  
Anna Michalska ◽  
Krzysztof Lech ◽  
Adam Figiel ◽  
Grzegorz P. Łysiak
Keyword(s):  
Physical Properties ◽  
Freeze Drying ◽  
Geographical Origin ◽  
Raw Material ◽  
Convective Drying ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Drying Time ◽  
Microwave Vacuum Drying ◽  
Apple Slices

Abstract The aim of the study was to determine the influence of four different growing locations of apples cv. ‘Jonagold’ in Europe on the drying kinetics and the physical properties of dried apple slices. The drying methods applied in the study (freeze-drying, convective drying, microwave-vacuum drying and combined drying) significantly affected the drying time, which was the shortest in the case of microwave vacuum drying. The geographical origin of the apples affected the chemical and physical properties of the raw material used for drying, and, consequently, the drying time. Water activity of dried samples was connected with the final dry matter, regardless of the geographical origin of the apples. Freeze-drying resulted in the lightest in colour products (L*), whereas microwave-vacuum dried products had the highest levels of yellow pigments (b*). The highest chroma and browning index values were noted for microwave-vacuum dried samples and were strongly influenced by the drying temperature. The mechanical properties of the apple slices were more dependent on the drying method and temperature of the process than on the geographical origin when the temperature exceeded 83 °C.

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