Hot-air Drying Kinetics of Yam Slices under Step Change in Relative Humidity

2016 ◽  
Vol 12 (8) ◽  
pp. 783-792 ◽  
Author(s):  
Hao-Yu Ju ◽  
Qian Zhang ◽  
A.S. Mujumdar ◽  
Xiao-Ming Fang ◽  
Hong-Wei Xiao ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Weibull Model ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Drying Rate ◽  
Rehydration Ratio ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Hot Air

Abstract The drying kinetics and mathematical modeling of hot-air drying of yam slices were investigated under two-stage relative humidity (RH) control strategy with 60 °C and 1.5 m/s as its constant drying temperature and air velocity, respectively. Results indicate high RH in the initial stage results in high sample’s temperature that enhances water diffusion in the falling rate drying period. Within the scope of current work, change in RH in the later drying period has insignificant influence on sample’s temperature rise while low RH can accelerate the drying rate. Compared to drying at constant 20 % RH at the same drying air temperature, the drying strategy of using 40 % RH over the first 15 min and then lowing to 20 % RH for the remainder time yields a shorter drying time. Weibull model adequately described the moisture content variation with time for all experiments with the scale parameter ranging from 105.02 to 122.38 min and the values of shape parameters from 0.988 to 1.183. The effective moisture diffusivity determined from the Weibull model varied from 2.032 to 2.610×10−8 m2/s. The rehydration ratio increased as the overall drying time was reduced. Microstructure examination shows that higher RH in the initial drying stage can lead to a more porous microstructure which enhances drying, while fast drying rate in the initial drying period generates a crust layer which hinders drying.

scholarly journals Effect of Freeze-Thaw Cycles on Juice Properties, Volatile Compounds and Hot-Air Drying Kinetics of Blueberry

Foods ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2362
Author(s):  
Lin Zhu ◽  
Xianrui Liang ◽  
Yushuang Lu ◽  
Shiyi Tian ◽  
Jie Chen ◽  
...  
Keyword(s):  
Antioxidant Activities ◽  
Drying Kinetics ◽  
Soluble Solids ◽  
Hot Air Drying ◽  
Fresh Sample ◽  
Drying Time ◽  
Air Drying ◽  
Freeze Thaw ◽  
Hot Air ◽  
Kinetics Of

This paper studied the effects of freeze-thaw (FT) cycles on the juice properties and aroma profiles, and the hot-air drying kinetics of frozen blueberry. After FT treatment, the juice yield increased while pH and total soluble solids of the juice keep unchanged. The total anthocyanins contents and DPPH antioxidant activities of the juice decreased by FT treatments. The electronic nose shows that FT treatments significantly change the aroma profiles of the juice. The four main volatile substances in the fresh juice are (E)-2-hexenal, α-terpineol, hexanal and linalyl formate, which account for 48.5 ± 0.1%, 17.6 ± 0.2%, 14.0 ± 1.5% and 7.8 ± 2.7% of relative proportions based on total ion chromatogram (TIC) peak areas. In the FT-treated samples, the amount of (E)-2-hexenal and hexanal decreased significantly while α-terpineol and linalyl formate remained almost unchanged. Repeated FT cycles increased the ethanol content and destroyed the original green leafy flavor. Finally, the drying kinetics of FT-treated blueberries was tested. One FT treatment can shorten the drying time by about 30% to achieve the same water content. The Deff values of the FT-treated sample are similar, which are about twice as large as the value of the fresh sample. The results will be beneficial for the processing of frozen blueberry into juice or dried fruits.

scholarly journals Comparative Evaluation of Drying Kinetics of Carrot Slices in Hot air and Microwave Drying

2021 ◽  
Vol 10 (4) ◽  
pp. 242-248
Author(s):  
Gitanjali Behera ◽  
◽  
Mitali Madhumita ◽  
J. Aishwarya Aishwarya ◽  
V. Gayathri ◽  
...  
Keyword(s):  
Microwave Drying ◽  
Quality Analysis ◽  
Rehydration Ratio ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Hot Air ◽  
Sensory Score ◽  
Kinetics Of ◽  
Different Thickness

Carrot is most the important vegetable grown throughout the World. It is also a very good source of βcarotene, α-carotene and zeaxanthin. The post-harvest losses because of having high moisture content limit the utilization of carrot. In the present investigation, the comparative analysis was done between hot air drying and microwave drying for different thickness of carrot slices. The quality analysis for both the dried products was performed and compared. The drying time was varied between 3.5 h to 10 h for try drying whereas for microwave drying it was 240 sec to 681.6 sec. The drying time reduces drastically in case of microwave drying in comparison to hot air drying. The moisture ratio for both dried techniques was found to decreasing with an increase in drying time. The microwave dried samples showed a better rehydration ratio than the hot air dried sample. Also, the dehydration ratio of dried carrot sample using microwave drying was found to be lowest compared to the hot air dried sample. The microwave dried carrot slices showed a better sensory score in terms of colour and shape than hot air dried sample. Therefore, microwave drying may be recommended to dry carrot slices to have better energy efficiencies

Microwave Assisted Convective Air Drying of Sugarloaf Pineapples (Ananas Comosus)

2021 ◽  
Vol 37 (5) ◽  
pp. 763-774
Author(s):  
Ernest Ekow Abano
Keyword(s):  
Air Temperature ◽  
Microwave Power ◽  
Moisture Diffusivity ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Microwave Assisted ◽  
Hot Air ◽  
Effective Moisture ◽  
Drying Conditions

HighlightsMicrowave pretreatment before drying reduced drying time significantly.Microwave-assisted drying increased the effective moisture diffusivity coefficient.Microwave pretreatment before convective hot-air drying improved quality parameters.The Middili et al. (2002) model best fitted the microwave-assisted drying of sugarloaf pineapples.Abstract. This study’s objective was to provide the optimum drying conditions to produce quality dried sugarloaf pineapples using microwave pretreatments before the conventional hot air drying. For this, the effect of microwave power (385 to 697 W), microwave time (2 to 4 min), and air temperature (50°C to 70°C) on the drying kinetics and quality of sugarloaf pineapple were evaluated using the Box Behnken response surface methodology. To reach a 17.44±0.09% kg/kg dry matter moisture content, we found the optimum drying conditions for sugarloaf pineapples to be 697 W microwave power for 2.26 min before convective hot air drying at a temperature of 64.75°C. The predicted drying time, ascorbic acid content, and browning index were 13.68 h, 20.89 mg/100 g, and 0.099 Abs unit at this optimum condition, respectively. The pineapple slices’ effective moisture removal rate pretreated with microwave before drying was higher than the control and was between 6.42 × 10-10 m2/s and 11.82 × 10-10 m2/s while ones without a microwave were between 3.54 × 10-10 m2/s and 8.78 × 10-10 m2/s for drying at air temperature between 50°C and 70°C. It was discovered that the Midilli et al. (2002) model was the most appropriate thin layer model for microwave-assisted drying of sugarloaf pineapples. The pineapple slices’ drying rate potential generally increased with microwave power and pretreatments time but not the corresponding increase in the air temperature. Drying time for microwave-assisted drying was in the range of 11 to 20 h, while the ones without microwaves were between 18 and 24 h. Therefore, microwaves should be considered a pretreatment step to the industrial production of sugarloaf pineapple to reduce drying time and produce better quality products. Keywords: Drying, Hot air, Microwave, Moisture diffusivity, Sugarloaf pineapple.

Drying Characteristics and Quality of Fresh White Waxy Corn Under Different Drying Methods

2021 ◽  
Author(s):  
Yanling He ◽  
Dan Huang ◽  
Yongjia Chen ◽  
Kaiyang Men ◽  
S. A. Sherif ◽  
...  
Keyword(s):  
Far Infrared ◽  
Drying Rate ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Infrared Drying ◽  
Sun Drying ◽  
Hot Air ◽  
Waxy Corn ◽  
Drying Quality

Abstract The drying characteristics and drying quality of fresh white waxy corn were investigated under three different drying methods (sun drying, hot-air drying and far-infrared drying) and different drying temperatures (55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C). The optimal drying method and drying condition were obtained by comparing the drying time and drying quality including damage rate, rehydration capacity and the contents of protein, fatty acid and starch. The results showed that the drying time of sun drying was the longest, while the drying quality was the best, i.e., the damage rate was the lowest and the nutrient retention was the highest. The far-infrared drying time was shorter and the quality was better than that of hot air drying. The higher the temperature, the faster the drying rate. The optimal drying temperature was 60 °C under far-infrared drying, which can effectively remove the water and keep the food quality. Besides, the drying rate was faster than hot air, and the color of the dried products was brighter. When hot air drying was used, the value of fatty acids did not change much below 65 °C, but it rose sharply above 65 °C. The optimal drying temperature was 65 °C, under which the drying rate was moderate and the quality was relatively good. If the production cost was considered, sun drying was the best, following the 60 °C far-infrared drying. This conclusion can provide a reference for the drying conditions of corn after harvest in agricultural production, and to a certain extent provide suggestions for the later drying treatment methods and treatment temperatures of fresh white waxy corn.

scholarly journals Hybrid and intermittent drying of carrot (Daucus carota var. Nantes)

2018 ◽  
Author(s):  
Dominik Mierzwa ◽  
Justyna Szadzińska ◽  
Krzysztof Bukowski
Keyword(s):  
Mass Transfer ◽  
Convective Drying ◽  
Drying Rate ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Hot Air ◽  
Intermittent Mode ◽  
Airborne Ultrasound

A combination of high power airborne ultrasound and microwaves in hot air drying was developed to investigate the effect of intermittent mode on process effectiveness and quality of carrot. The drying experiments were carried out in an innovative hybrid dryer. The course of moisture ratio, drying rate, specific energy and water consumption, colour, water activity and shrinkage were discussed. The results showed that intermittent ultrasound and microwaves in convective drying accelerate the heat and mass transfer, leading to shorter drying time and faster drying rate. It was found that hybrid-intermittent drying can improve the energy efficiency and product quality. Keywords: intermittent drying; ultrasound; microwaves; energy; shrinkage

Study on a Combination Drying Technique of Shrimp

2012 ◽  
Vol 260-261 ◽  
pp. 804-807
Author(s):  
Ya Xiang Bai ◽  
Yu Cai Hu ◽  
Qiang Huang
Keyword(s):  
Freeze Drying ◽  
Sensory Properties ◽  
Drying Rate ◽  
Rehydration Ratio ◽  
Drying Time ◽  
Air Drying ◽  
Combined Process ◽  
Highly Efficient ◽  
Sensory Qualities

In order to develop a highly efficient drying technique for shrimp, a combination of air drying (AD) and vacuum freeze drying (FD) is examined. The drying rate of combination drying, the shrinkage, rehydration ratio, and sensory properties, such as the color and trimness, of the dried product in the AD–FD method are measured. Compared with FD, the combined process consumes less drying time, compared with AD drying alone. Also the product processed by combined drying displays lower shrinkage, higher rehydration rate and better sensory qualities.

Mathematical modeling of hot-air drying kinetics of red bell pepper (var. Lamuyo)

2007 ◽  
Vol 79 (4) ◽  
pp. 1460-1466 ◽  
Author(s):  
A. Vega ◽  
P. Fito ◽  
A. Andrés ◽  
R. Lemus
Keyword(s):  
Mathematical Modeling ◽  
Drying Kinetics ◽  
Bell Pepper ◽  
Hot Air Drying ◽  
Air Drying ◽  
Hot Air ◽  
Kinetics Of

The influence of inhibit avoid water defect responses by heat pretreatment on hot air drying rate of spinach

2016 ◽  
Vol 168 ◽  
pp. 113-118 ◽  
Author(s):  
Takashi Watanabe ◽  
Takahiro Orikasa ◽  
Hiroshi Shono ◽  
Shoji Koide ◽  
Yasumasa Ando ◽  
...  
Keyword(s):  
Drying Rate ◽  
Hot Air Drying ◽  
Air Drying ◽  
Heat Pretreatment ◽  
Hot Air

scholarly journals Investigation of influence of pre-treatment and low-temperature on drying kinetics, sorption properties, shrinkage and color of brown seaweeds (Saccharina Latissima)

2018 ◽  
Author(s):  
Ignat Tolstorebrov ◽  
Trygve Magne Eikevik ◽  
Inna Petrova ◽  
Yulia Shokina ◽  
Michael Bantle
Keyword(s):  
Relative Humidity ◽  
Salt Content ◽  
Sorption Isotherms ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Saccharina Latissima ◽  
Diffusivity Coefficient ◽  
High Accumulation ◽  
Drying Time ◽  
Brown Seaweeds

Drying kinetics of Saccharina latissima (raw and blanched) at low temperatures (10.0, 25.0 and 38.0 °C) was studied. The effective moisture diffusivity coefficient varied due to temperature alterations in the range between 1.4 and 4.5 10-10 m2/s for raw and 0.91 and 2.56 10-10 m2/s for blanched seaweeds. Significant changes in structural properties and chemical composition resulted in a much longer drying time of blanched seaweeds, when compared with raw. Drying temperature of 38.0 °C resulted in more brown color, when compared with other samples. Sorption characteristics of dried raw seaweeds depended on salt content and showed high accumulation of moisture at relative humidity of air of 80.0 %. The blanched seaweeds showed linear accumulation of moisture within increasing of relative humidity of drying air from 20.0 to 80.0 %, but high level of hysteresis was determined between sorption and desorption isotherms. The shrinkage development within dewatering of blanched and raw samples was also studied. Keywords: brown seaweeds, drying kinetics, sorption isotherms, color 

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