A Comparative Study of Combined Microwave Techniques for Longan (Dimocarpus longan Lour.) Drying with Hot Air or Vacuum

2017 ◽  
Vol 13 (7) ◽  
Author(s):  
Krit Apinyavisit ◽  
Adisak Nathakaranakule ◽  
Somchart Soponronnarit ◽  
Gauri S. Mittal
Keyword(s):  
Energy Efficient ◽  
Preference Score ◽  
Drying Method ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Microwave Vacuum Drying ◽  
Hot Air ◽  
Drying Techniques ◽  
Microwave Techniques

AbstractThe aim of this study is to find a better drying method to replace conventional hot air drying (HAD) in terms of faster, energy efficient and better product quality. Two alternative drying techniques, microwave combined with hot air drying (MHD) and microwave vacuum drying (MVD), are compared in this study to dry peeled and destoned longan fruit. Both MHD and MVD reduced the drying time up to 48 % and energy consumption as compared to HAD. These techniques provided lower product redness, yellowness and shrinkage but higher lightness and porous structure as compared to HAD. MVD reduced hardness and toughness of the dried product. MHD provided the highest preference score in terms of colour and shape and was as acceptable as the commercial product dried by HAD. MHD is the most suitable method for longan drying.

Effects of drying methods on color retention and chlorophyll of celery (ApiumgraveolensL.), spinach (Spinacia oleraceaL.), Malabar spinach (Basella albaL.)

2020 ◽  
pp. 53-61
Author(s):  
Dat Q Tran
Keyword(s):  
Microwave Drying ◽  
Drying Methods ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Color Retention ◽  
Hot Air ◽  
Drying Techniques ◽  
Dried Vegetables

Dried vegetables are considered convenient for storage, transportation and preservation. The different drying techniques could influence the quality of resulting products. This study aimed to evaluate the effects of three distinguish drying methods as hot-air drying, foam-mat drying and microwave drying on the color retention and chlorophyll of green vegetables powder. Fresh spinach(Spinacia oleraceaL.), celery (Apium graveolensL.), Malabar spinach (Basella albaL.) were dried by different methods: hot air at 60oC, foam-mat at 60oC and microwave at 270 W until the samples reached approximately 9% of moisture content (wb). The drying time of the dried samples by microwave, foam-mat and hot-air method were 60, 210 and 240 min, respectively. Foam-mat dried vegetables were found to have the best quality in terms of color and the residual chlorophyll content. The findings suggest that foam-mat drying is promising in dried vegetable processing

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.

Assessment of Quality Attributes of Banana Slices Dried by Different Drying Methods

2014 ◽  
Vol 10 (2) ◽  
pp. 251-260 ◽  
Author(s):  
Kianoosh Pirnazari ◽  
Ali Esehaghbeygi ◽  
Morteza Sadeghi
Keyword(s):  
Moisture Transfer ◽  
Color Change ◽  
Drying Methods ◽  
Drying Method ◽  
Hot Air Drying ◽  
Drying Time ◽  
Moisture Movement ◽  
Air Drying ◽  
Hot Air ◽  
Significant Difference

Abstract In the present study, banana slices were dried and compared using electrohydrodynamic (EHD) drying method at 4.5, 6.5, and 8.5 kV/cm; oven at 50, 60, and 70°C; and hot-air drying at 50, 60, and 70°C at a constant air velocity of 1.5 m/s. ANOVA showed that drying method had a significant effect on drying time, rehydration capacity, shrinkage, color features (L*, a*, b*, and ∆E), and consumed energy. The values of consuming energy for EHD at 8.5 kV/cm, oven, and hot-air drying at 70°C were 2.99, 20.9, and 81.7 kJ/g run on full capacity of each dryer, respectively. Oven drying led to a greater color change than did hot-air. No significant difference was observed between the color change feature ∆E for EHD and hot-air dried samples in the orthogonal contrast analysis. The falling rate period for EHD moisture movement showed that diffusion was describing the moisture gradients and the internal moisture transfer was dominant. EHD is not fast; however, its advantages like less energy needed, lower shrinkage, and great rehydration capacity make it a good choice for combining with other convection drying methods.

scholarly journals STUDY OF PHYSICOCHEMICAL PROPERTIES OF CAPSICUM POWDER BY DIFFERENT DRYING TECHNIQUES

2021 ◽  
Vol 10 (4) ◽  
pp. 3110-3114
Author(s):  
Madhumita Saha
Keyword(s):  
Bulk Density ◽  
Freeze Drying ◽  
Microwave Drying ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Hot Air ◽  
Drying Techniques ◽  
Peroxidase Enzyme ◽  
Density Values

The objective of this study was to analyse the effects of phytochemical parameter, physical parameter, color, and sensory analysis in green capsicum by different drying processes (microwave, freeze, and hot air drying). Results showed an increase in microwave output power (600W), decreased drying time, moisture content, Chroma, and bulk density values. The Freeze drying process significantly improved the lightness of dried capsicum. Due to take less time for the Microwave drying technique, phytochemical parameters are intact in capsicum; on the other side, color degradation has been occurred due to the Maillard reaction (L*=29.34±0.08, a*=6.98±0.09,b*=15.36±0.10). Bulk density (0.335±0.01) and dispersibility (40±2.00%) were highest in Microwave drying powder. The capsaicin content of dried capsicum was higher than the fresh capsicum sample, but compared to the different drying techniques, the Microwave drying sample has higher capsaicin content than the Hot air drying and Freeze-drying samples. The lower capsaicin content in fresh capsicum may occur due to the catalytic activity of the peroxidase enzyme. The capsaicin content of all dried capsicum varied between 1.91±0.05 and 3.31±0.16 mg/100 g. In this research, the Microwave drying powder of capsicum was the best product for its highest antioxidant content and other physical properties.

scholarly journals Kurutma Yöntemlerinin Deveci Armudunun Kurutma Kinetiği ve Renk Parametreleri Üzerine Etkisi

2021 ◽  
Vol 9 (5) ◽  
pp. 897-908
Author(s):  
Ilknur Alibas ◽  
Aslıhan Yılmaz ◽  
Seda Günaydın ◽  
Begüm Arkain
Keyword(s):  
Energy Consumption ◽  
Specific Energy Consumption ◽  
Initial Moisture Content ◽  
Quality Parameters ◽  
Drying Method ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Hot Air ◽  
Thin Layer Drying

Deveci pear (Pyrus communis L. cv. Deveci) slices, whose initial moisture content is 5.24 ± 0.003 kgsu kgKM-1 (%83.95 ± 0.01 w.b), were dried by shade drying and hot-air drying at 60, 80 and 100°C until the final moisture reached 0.13 ± 0.001 kgsu kgKM-1 (%11.40 ± 0.06 w.b), and the drying processes of these methods were completed in 11150, 437, 252, and 148 minutes, respectively. In the study, experimentally obtained time-dependent moisture ratios were modeled using twenty different thin-layer drying equations. Accordingly, the model that gives the closest results to experimental data for 60°C and 100°C was the Modified Henderson & Pabis's equation. On the other hand, Alibas equation and Jena & Das equation were found to be the best models in shade drying and hot-air drying at 80°C, respectively. Despite no energy consumption in the shade drying method, some reasons such as this method being quite long and causing negative effects on the quality parameters of the product revealed that the shade drying method was not suitable for drying of Deveci pear. It was observed that total energy consumption increased with the increase of the drying temperature. Also, it was determined that the increase in temperature negatively affected the quality parameters. It was found to be a suitable method for drying the Deveci pear of the hot-air drying at 60°C due to the operating parameters such as drying time and specific energy consumption, as well as quality parameters such as brightness, redness, yellowness, chroma, hue angle, total color change and browning index were very close to the fresh product.

Determination of Antioxidant Activity of Edible Calendula Flowers by Hot-air Drying Time

2018 ◽  
Vol 26 (4) ◽  
pp. 202-208
Author(s):  
Sang Im Oh ◽  
Seo Young Kim ◽  
Ja Hee Lee ◽  
Ae Kyung Lee
Keyword(s):  
Antioxidant Activity ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Hot Air

scholarly journals Effects of Freeze Vacuum Drying Combined with Hot Air Drying on the Sensory Quality, Active Components, Moisture Mobility, Odors, and Microstructure of Kiwifruits

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Lihui Zhang ◽  
Yu Qiao ◽  
Chao Wang ◽  
Li Liao ◽  
Lu Liu ◽  
...  
Keyword(s):  
Sensory Quality ◽  
Antioxidant Properties ◽  
Bound Water ◽  
Principal Component ◽  
Vacuum Drying ◽  
Active Components ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Hot Air

In this study, freeze vacuum drying (FVD), hot air drying (AD), and FVD combined with AD (FVD-AD) were used to dry kiwifruits. Dried products were analyzed comprehensively on their sensory quality, active components, moisture mobility, odors, and microstructure. Results showed that the FVD-AD saved time by 38.22% compared with FVD while maintaining an acceptable product quality. The antioxidant properties of FVD-AD were lower than those of FVD but significantly higher than those of AD. Moreover, compared with FVD products, FVD-AD products were moderately hard (5252.71 ± 33.53 g) and improved in color, bound water, and microstructure. Additionally, FVD-AD consumed lesser drying time and energy than FD. According to cluster analysis, the odors of FVD-AD products were similar to those of the fresh ones. Principal component analysis of physicochemical and drying cost indicated that FVD-AD was a promising processing technique for functional kiwifruit snacks.

scholarly journals Effect of Hot Air Thin Layer Drying Temperature on Physicochemical and Textural Properties of Dried Horseradish

2019 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Pranabendu Mitra ◽  
Md. Abdul Alim ◽  
Venkatesh Meda
Keyword(s):  
Textural Properties ◽  
Drying Method ◽  
Rehydration Ratio ◽  
Hot Air Drying ◽  
Air Drying ◽  
Medicinal Uses ◽  
Drying Temperature ◽  
Hot Air ◽  
Thin Layer Drying

The horseradish (Armoracia rusticana) is an important crop as ingredients for many commercial food products and medicinal uses. However, the horseradish is perishable and preservation of this crop for supplying year-round is necessary. Drying can be used to preserve the horseradish but establishing a suitable drying method and conditions are important for product quality of dried horseradish. The objective of this study was to investigate the effects of hot air-drying temperatures on the physicochemical and textural properties of dried horseradish samples to determine the appropriate hot air-drying conditions. The sliced horseradish samples were dried at 55, 65, 75, 85 and 95 ℃ using a conventional hot air drier. The physicochemical and textural properties of the dried horseradish samples were determined, and the results were compared for different drying temperatures. The ANOVA analysis indicated that the drying temperature affected the physicochemical and textural properties of dried horseradish samples significantly (p<0.05). The experimental results indicated that the moisture content (9.18-6.15%,wb), aw (0.06-0.03), porosity (31.47-12.13%) and rehydration ratio (82.74 -44.47%) decreased and piece density (0.63-0.84 g/mL), hardness (193.63 -298.31N), cohesiveness (1.04-1.32), gumminess (202.13-390.12) and chewiness (635.08-1223.55) of dried horseradish samples increased with the drying temperature. Power law model indicated that the porosity was linearly corelated to the rehydration ratio of dried horseradish samples. The overall results revealed that relatively lower (55-65 ℃) drying temperature range was suitable to keep the quality of the dried horseradish samples. The findings of this study are expected to be helpful for the commercial drying of horseradish samples using hot air-drying method.

scholarly journals Influence of Different Hot Air Drying Temperatures on Drying Kinetics, Shrinkage, and Colour of Persimmon Slices

Foods ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 101 ◽  
Author(s):  
Senadeera ◽  
Adiletta ◽  
Önal ◽  
Di Matteo ◽  
Russo
Keyword(s):  
Moisture Content ◽  
Quadratic Model ◽  
Drying Process ◽  
Air Velocity ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Drying Characteristics ◽  
Drying Temperature ◽  
Hot Air

Drying characteristics of persimmon, cv. “Rojo Brillante”, slabs were experimentally determined in a hot air convective drier at drying temperatures of 45, 50, 55, 60, and 65 °C at a fixed air velocity of 2.3 m/s. It was observed that the drying temperature affected the drying time, shrinkage, and colour. Four empirical mathematical models namely, Enderson and Pabis, Page, Logarithmic, and Two term, were evaluated in order to deeply understand the drying process (moisture ratio). The Page model described the best representation of the experimental drying data at all investigated temperatures (45, 50, 55, 60, 65 °C). According to the evaluation of the shrinkage models, the Quadratic model provided the best representation of the volumetric shrinkage of persimmons as a function of moisture content. Overall, higher drying temperature (65 °C) improved the colour retention of dried persimmon slabs.

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