Optimization of ohmic heating-assisted osmotic dehydration as a pretreatment for microwave drying of quince

2021 ◽  
pp. 108201322199161
Author(s):  
Naciye Kutlu
Keyword(s):  
Microwave Power ◽  
Ohmic Heating ◽  
Osmotic Dehydration ◽  
Sucrose Concentration ◽  
Holding Time ◽  
Microwave Drying ◽  
Total Phenolic ◽  
Rehydration Ratio ◽  
Electrical Field ◽  
Electrical Field Strength

In this study, the ohmic heating system was used as a novel application for osmotic dehydration of quince. After osmotic dehydration, samples were dried by microwave. In this regard, the effects of process variables such as electrical field strengths (20, 30 and 40 V/cm), holding time (10, 20 and 30 minutes), microwave power (90, 180 and 270 W) and sucrose concentration (0%, 25% and 50%) on dielectric constant, dielectric loss factor, rehydration ratios, total phenolic compounds and color values were investigated by response surface methodology (RSM). Optimum conditions were found as 40 V/cm electrical field strength, 30 min holding time, 16.67% sucrose concentration and 270 W microwave power. Total phenolic content, rehydration ratio, color differences and dielectric properties of the novel method were found to be higher than that of control. Moreover, Midilli and Wang & Sing models gave the superior fit to the moisture ratio data obtained during drying.

scholarly journals Influence of vacuum microwave drying parameters on the physicochemical properties of red beetroots

2021 ◽  
Vol 23 (96) ◽  
pp. 8-14
Author(s):  
Yan Liu ◽  
Sergey Sabadash ◽  
Dan Gao ◽  
Feifei Shang ◽  
Zhenhua Duan
Keyword(s):  
Physicochemical Properties ◽  
Microwave Power ◽  
High Vacuum ◽  
Microwave Drying ◽  
Water Evaporation ◽  
Total Phenolic ◽  
Rehydration Ratio ◽  
Drying Time ◽  
Vacuum Degree ◽  
Vacuum Microwave

In recent years, the consumption of red beetroots has increased significantly due to its good taste, high nutritional value and abundant active compounds. Red beetroot is prone to spoilage due to its high moisture content, making it perishable. Vacuum microwave drying is a gentle drying method by inducing fast water evaporation from food products at low temperature, which can improves the product quality. The objective of this study was to investigate the effects of vacuum microwave drying parameters, including microwave power (500, 1000, and 1500 W) and vacuum degree (50, 70, and 90 KPa), on the physicochemical properties (drying time, rehydration ratio, color change, and contents of betalain and total phenolic) of red beetroots. The results showed that microwave power and vacuum degree had significant effects on the physicochemical properties of red beetroots. All the red beetroots after vacuum microwave drying had higher lightness (L*), lower redness (a*) and yellowness (b*) than that of fresh red beetroots. The drying time, rehydration ratio, betacyanin content and betaxanthin content of red beetroots decreased significantly with the increase of microwave power (P < 0.05), while the rehydration ratio, color parameters (a*, b*, and chroma values), betacyanin content and betaxanthin content of red beetroots significantly increased with the increase of vacuum degree (P < 0.05). Compared with other microwave powers, the red beetroots dried at 500 W showed longer drying time, higher rehydration ratio, more yellowish hue, and higher contents of betacyanin and betaxanthin. The lowest values of total color difference (∆E) and hue angle (H°) of dried red beetroots were obtained at microwave power of 1500 W. The dried red beetroots obtained at 90 KPa had the shortest drying time, the highest rehydration ratio, the best color, and the highest contents of betacyanin and betaxanthin. Meanwhile, the red beetroots dried at 50 KPa had the highest total phenolic content (12.47 ± 0.09 mg GAE/g). Based on the physicochemical properties of red beetroots, vacuum microwave drying at low microwave powers and high vacuum degree appears to be a suitable method for drying red beetroots.

scholarly journals Microwave and convective air on drying of araucaria angustifolia seeds

2021 ◽  
Vol 42 (3Supl1) ◽  
pp. 1487-1498
Author(s):  
Naiara Nobre dos Reis ◽  
◽  
Joyce Yumi Taira ◽  
Leda Battestin Quast ◽  
Ernesto Quast ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Microwave Power ◽  
Microwave Drying ◽  
Alternative Methods ◽  
Total Phenolic ◽  
Araucaria Angustifolia ◽  
Internal Temperature ◽  
Drying Process ◽  
Hot Air ◽  
Conventional Drying

Microwave drying has shorter processing times compared with convection drying, which results in high-quality products and reduced energy consumption. The objective of this study is to evaluate the drying process of Araucaria angustifolia seeds using hot air at atmospheric pressure by applying microwaves (300 W and 500 W), and comparing them with the conventional drying process using hot air (80 °C). The drying time using hot air with microwaves at 500 W and 300 W was reduced by 83.33% and 73.89%, respectively, compared with conventional drying. The drying process occurred in the transient regime, with the predominance of a period of decreasing drying rate. The internal temperature of Araucaria seeds increased with the exposure time to the drying process, whereas the moisture content decreased. This tendency was greater for seeds subjected to electromagnetic fields, especially those exposed to higher power. The total phenolic compounds (TPCs) were lower by microwave drying when compared with conventional drying. The TPC loss was influenced by the internal temperature of the seed. Alternative methods to promote the increased retention of phenolic compounds during the drying process include decreasing the microwave power before the end of drying, combining traditional microwave-associated drying methods, and controlling the applied microwave power.

Study on the Effect of Vacuum Microwave Drying on Quality of Okra

2013 ◽  
Vol 791-793 ◽  
pp. 132-136 ◽  
Author(s):  
Jing Yi Li ◽  
Zhen Hua Duan
Keyword(s):  
Microwave Power ◽  
Fracture Resistance ◽  
Colour Change ◽  
Microwave Drying ◽  
Rehydration Ratio ◽  
Drying Time ◽  
Vacuum Degree ◽  
Vacuum Microwave ◽  
The Impact

The purpose of this paper is to investigate the impact of vacuum microwave drying on the quality of okra. The curves of colour, fracture resistance, rehydration ratio and the content of vitaminC were obtained at various drying times, vacuum degrees and microwave powers. Results showed that an increase in drying time and microwave power resulted in serious colour change when compare the dry product to fresh okra. However, the higher the vacuum, the slighter the colour changed. The fracture resistance decreased and the brittleness was good when drying time was increased to high level of 14min and 16min. Increasing vacuum degree also made fracture resistance decreased; rehydration ratio increased with the time and microwave power increased, but decreased if the time exceeds 14min. The rehydration ratio of okra is also affected by the vacuum degree, increasing which led the rehydration ratio increased significantly at the beginning of drying and then slowly; the greater the drying time and microwave power, the more lost of vitaminC, however, higher vacuum degree was found to be beneficial to save the vitaminC.

scholarly journals Osmotic Dehydration and Assessment of Quality Attributes of Seasonal Vegetable Crops: Carrot and Beetroot Cubes

2020 ◽  
Vol 5 (4) ◽  
pp. 199-217
Author(s):  
Shamsher Ali ◽  
◽  
Alka Sharma
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Osmotic Dehydration ◽  
Sucrose Concentration ◽  
Quality Attributes ◽  
Vegetable Crops ◽  
Rehydration Ratio ◽  
Overall Acceptability ◽  
Nacl Concentration ◽  
Osmotic Solution

Fulfilling the food demand of a growing population is the biggest challenge as lot of food globally got wasted due to improper storage and processing. Osmotic dehydration offers high-quality preservation and maintenance of the integrity of fruits & vegetables. Response surface methodology was performed to estimate the main effect of osmotic dehydration process on quality attributes of carrot and beetroot cubes. Higher values of the osmotic solution of salt and sucrose at sample to solution ratio of 1:5 had provoked higher flows of water and solutes through the carrot and beetroot cubes. The range of NaCl concentration varies from 4-12 % w/v in carrot and 12-16 % w/v in beetroot for 2, 4 and 6 hour. However, sucrose concentration varies from 40-60º Brix in both carrot and beetroot. Quality attribute of carrot and beetroot including ascorbic acid, carotenoid, total phenol etc. didn’t changed on recommended process variables 50º Brix of sucrose + 8 % w/v sodium chloride for carrot and 50º Brix of sucrose + 14 % w/v NaCl for beetroot under osmotic dehydration for 4 hours. It was considered to get maximum water loss, weight reduction, subsequent rehydration ratio, overall acceptability and minimum solute gain of rehydrated product. Keywords: Osmotic dehydration; Carrot; Beetroot; Preservation; Response Surface Methodology

scholarly journals Colour and rehydration properties of bay leaves dried by convective and microwave methods

2019 ◽  
Vol 11 (1) ◽  
pp. 80-83
Author(s):  
A. Polat ◽  
N. Izli
Keyword(s):  
Microwave Power ◽  
Microwave Drying ◽  
Convective Drying ◽  
Drying Process ◽  
Rehydration Ratio ◽  
Air Temperatures ◽  
Colour Parameters ◽  
Colour Changes ◽  
Hue Angle ◽  
Increasing Temperature

Abstract. This study aims to evaluate the effect of the convective and microwave dying methods on the colour parameters (L*, a*, b*, C,  and ΔE) and rehydration ratio of bay leaves. Drying experiments were conducted using 350 and 460W of microwave powers and air temperatures of 50, 60 and 70C. Different microwave powers show significant effect on colour of dried bay leaves. Increasing microwave power, a* (redness/greenness),  (hue angle) and ΔE (total colour changes) values increased whereas L* (lightness), b* (yellowness/blueness) and C (Chroma) values decreased. For the convective drying, although there are changes in the values of the colour parameters (L*, a*, b*, C and ), there are no significant differences in the values of the total colour changes (ΔE) statistically (P>0.05). The effect of microwave power levels and air temperature on rehydration characteristics was determined. It was found that the rehydration ratio values decreased with an increasing temperature and increasing power levels. The highest rehydration ratio was recorded for the samples dried at 350W and the lowest ratio was seen in a sample dried at 70°C. Microwave drying can be a practical drying process, an alternative to convective drying for drying bay leaves.

Microwave Drying of Sweet Potato (Ipomoea batatas (L.)) Slices: Influence of the Osmotic Pretreatment

2016 ◽  
Vol 367 ◽  
pp. 167-174 ◽  
Author(s):  
J.R.J. Junqueira ◽  
K.S. Mendonça ◽  
J.L.G. Corrêa
Keyword(s):  
Moisture Content ◽  
Mathematical Models ◽  
Sweet Potato ◽  
Microwave Power ◽  
Osmotic Dehydration ◽  
Drying Kinetics ◽  
Microwave Drying ◽  
Distribution Model ◽  
Drying Time ◽  
Osmotic Agents

Drying of sweet potato (Ipomoea batatas (L.)) slices by microwave with and without osmotic dehydration (OD) as a pretreatment was studied. Three osmotic agents (sucrose, sorbitol and fructose) were employed. Drying continued until final moisture content of 20 kg water 100 kg-1 sample. Two different microwave output powers (180 and 350W) were used. The drying kinetics was modeled by mathematical models from the literature. The use of OD and higher microwave power carried out to shorter drying time. Among the tested mathematical models, the Weibull distribution model presented good fitness for drying kinetics obtained in both microwave power.

Study of color kinetics of banana (Musa cavendish) under microwave drying by application of image analysis

2020 ◽  
pp. 108201322098133
Author(s):  
Sagar Nagvanshi ◽  
Subbarao Kotra Venkata ◽  
TK Goswami
Keyword(s):  
Microwave Power ◽  
Vision System ◽  
Power Level ◽  
Microwave Drying ◽  
Slice Thickness ◽  
Order Kinetic ◽  
Drying Time ◽  
Volumetric Heating ◽  
Kinetics Of ◽  
Microwave Power Level

Microwave drying works on the volumetric heating concept promoted by electromagnetic radiation at 0.915 or 2.450 GHz. In this study, banana ( Musa Cavendish) was taken as the sample and treated under microwave drying. The effect of two process variables, namely slice thickness (2, 3.5, and 5 mm) and microwave power (180 W, 360 W, and 540 W), were studied on drying kinetics and color kinetics. It was observed that the inverse variation relationship exists between drying time and microwave power level while drying time and slice thickness exhibited a direct variation relationship. A Computer Vision System (CVS) was developed to measure the color values of banana in CIELab space using an algorithm written in MATLAB software. Once the color parameters were obtained, they were fitted in First and Zero-order kinetic models. Both models were found to describe the color values adequately. This study concludes that microwave drying is a promising dehydration technique for banana drying that reduces the significant time of drying. Application of CVS is an excellent approach to measure the surface color of banana.

scholarly journals Microwave-assisted extraction of non-polar compounds from pistachio hull and characterization of extracts

2018 ◽  
Vol 69 (3) ◽  
pp. 260 ◽  
Author(s):  
H. N. Özbek ◽  
D. Koçak Yanık ◽  
S. Fadıloğlu ◽  
H. Keskin Çavdar ◽  
F. Göğüş
Keyword(s):  
Microwave Power ◽  
Polar Compounds ◽  
Good Alternative ◽  
Tocopherol Content ◽  
Extraction Time ◽  
Total Phenolic ◽  
Microwave Assisted Extraction ◽  
Solid Ratio ◽  
Microwave Assisted ◽  
Assisted Extraction

Soxhlet and microwave assisted extraction (MAE) methods were used to obtain non-polar compounds from pistachio hull. MAE parameters (liquid to solid ratio, microwave power, and extraction time) were studied to obtain maximum extraction yield. The optimal conditions were found to be liquid to solid ratio of 15:1 (v/w), microwave power of 250 W and extraction time of 12.5 min. The extraction yields were 9.81 and 9.50% for MAE and Soxhlet methods, respectively. The total phenolic content, antioxidant activity and tocopherol content of the extract obtained by MAE was found to be significantly higher than those of the Soxhlet extract (p < 0.05). The results showed that the extract contained α-tocopherols (567.65 mg/kg) and oleic acid (48.46%) as the major tocopherols and fatty acids. These findings propose that hull extracts can be considered as a good source of natural bioactive compounds and MAE can be a good alternative to the traditional Soxhlet method.

scholarly journals Comparative Study of Hot Air Drying and Microwave Drying for Dewatered Sludge

2021 ◽  
Author(s):  
Wittawat Wulyapash ◽  
Awassada Phongphiphat ◽  
Sirintornthep Towprayoon
Keyword(s):  
Microwave Power ◽  
Specific Energy Consumption ◽  
Microwave Drying ◽  
Drying Methods ◽  
Drying Time ◽  
Hot Air ◽  
Air Temperatures ◽  
Dewatered Sludge ◽  
Dried Sludge ◽  
Seafood Processing

Abstract Large amounts of sludge are generated from wastewater treatment in seafood processing industries. Most of the dewatered sludge in Thailand is not utilized and disposed by landfilling. The dried sludge utilization as refuse-derived fuel (RDF) is an alternative solution due to the gross calorific value (GCV), which is greater than 21.9 MJ/kg. However, the key obstacle is its high moisture content of 87.4% (wet basis). Therefore, drying methods using hot air and microwave techniques were investigated for preparing dried sludge. The effects of hot air temperatures (100-150 °C) and microwave power levels (100-800 W) were compared on drying kinetics, specific energy consumption (SEC), and characteristics of the dried products. The results showed that drying times were decreased by increasing the hot air temperatures. In the same way, the increase in microwave power levels decreased the drying time. The application of microwaves contributed to reducing the drying time by more than 46% compared to the hot air. The reduction of drying times resulted in the saving SEC. The GCV of the dried sludge decreased with the decrease in the volatile matter (VM) due to the high component of VM as 79.5-80.3% (dry ash-free basis). The sludge dried by the microwaves showed a lower GCV than the hot air products. However, dried sludges still had high GCV (≥ 20.8 MJ/kg). Furthermore, the minimal variation of the product characteristics demonstrated that the microwave technique could be applied as an alternative drying method with a rapid process compared to the conventional hot air technique.

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