Convective, vacuum and microwave drying kinetics of mallow leaves and comparison of color and ascorbic acid values of three drying methods

Alibas, Ilknur; Köksal, Nezihe

doi:10.1590/s0101-20612014005000033

Cited by 24 publications

(11 citation statements)

References 25 publications

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“…As shown in Table , the drying constant k for the kiwifruit slice in both of these two models was higher as microwave power density or vacuum degree increased, which was lower as sample thickness increased. These data point out that following the increase in microwave power density and vacuum degree, drying curve becomes steeper, indicating faster drying of the product (Alibas and Koksal ). Furthermore, k value variation range was different under different drying conditions.…”

Section: Resultsmentioning

confidence: 78%

Drying Characteristics and Processing Parameters for Microwave-Vacuum Drying of Kiwifruit (A ctinidia deliciosa ) Slices

Tian

Zhao

et al. 2015

Journal of Food Processing and Preservation

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This study experimented on microwave-vacuum (MWV) drying of kiwifruit (Actinidia deliciosa) slices as a way to improve drying productivity and the quality of dried fruit. The effects of microwave power density, sample thickness and vacuum degree on the drying characteristics of kiwifruit slices were studied. The results showed that these three factors had significant effects on the vitamin C and chlorophyll contents and on the rehydration capacity of dried kiwifruit slices, as well as the total drying time. The processing parameters of MWV drying of kiwifruit slices were optimized by using Box-Behnken design with a quadratic regression model built by response surface methodology. The optimum processing parameters were experimentally determined as microwave power density at 7.7 W, sample thickness of 6.0 mm and MWV drying for 11.5 min at a vacuum degree of −90 kPa. High-quality dried kiwifruit slices can be created under these conditions using this drying process. PRACTICAL APPLICATIONSKiwifruit (Actinidia deliciosa) has become a popular fruit because of its bright green flesh, high level of vitamin C and because it contains a wide variety of phytonutrients, including carotenoids, lutein, phenolics, flavonoids and chlorophyll. It needs some form of preservation to extend its shelf life. Microwave-vacuum (MWV) drying is a novel alternative that combines the advantages of both microwave drying and vacuum drying. The objectives of this study were to investigate the effect of microwave power density, sample thickness and vacuum degree on the MWV drying characteristics and quality of MWV-dried kiwifruit slices, and to evaluate a suitable drying model for describing the drying process. In addition, the process parameters of MWV drying were optimized by response surface methodology. This present study provides the theoretical basis for industrial-scale production.

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Section: Resultsmentioning

confidence: 78%

Drying Characteristics and Processing Parameters for Microwave-Vacuum Drying of Kiwifruit (A ctinidia deliciosa ) Slices

Tian

Zhao

et al. 2015

Journal of Food Processing and Preservation

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“…He found that L* value of dried samples at 850 W microwave power, which was the highest microwave power applied, was closer to fresh samples. Similarly, Alibas and Koksal (2014) dried mallow leaves using three different techniques (convective, vacuum, and microwave drying). The results of this study showed that microwave-dried samples had the most similar color values to fresh samples.…”

Section: Resultsmentioning

confidence: 99%

Phenolic content and some physical properties of dried broccoli as affected by drying method

Yılmaz

Şakıyan

Mazı

et al. 2018

Food sci. technol. int.

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Broccoli samples ( Brassica oleracea) with an initial moisture content of 82.87% (wb) were dried using microwave technology (18, 36, and 54 W/g). Convective drying was used as a control group. The dependent variables investigated in the study were phenolic content, color, rehydration capacity, and microstructure of broccoli samples. Moreover, the best fitting thin layer model to the experimental moisture ratio was determined. The phenolic contents were found as 892.4, 740.6, and 759.8 mg gallic acid/100 g dry matter for fresh, convective dried, and microwave (MW) dried at 54 W/g broccoli samples, respectively. The total phenolic content of samples dried at 54 W/g was closest to fresh samples compared to other MW power intensities and convective drying. A similar result was obtained for color values too. L*, a*, and b* of microwave-dried samples at 54 W/g were comparable to fresh broccoli. Another important result obtained from the study was the insignificant effect of drying conditions on rehydration capacity. In addition, it was found that microwave power had a positive effect on drying time; as the microwave powers applied were compared, the shortest drying time was reached at 54 W/g. When the process durations of microwave drying and convective drying were compared, it can be reported that a much lower process time for microwave drying was obtained with respect to convective drying. Drying in microwave oven has reduced the drying time by 49-52%. In the light of the results obtained, it may be declared that it is possible to produce high-quality dried broccoli samples in a very short time by using microwave drying at 54 W/g.

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“…Drying is defined as the removal of the water or any sort of liquid in a substance. The purpose of the drying is to stop the development of microorganisms and biochemical reactions that might occur in the products by removing free water, thus enabling the product to last longer with the microorganisms which are reduced to a level at which they can reproduce no longer [5,7,8,9]. In addition, color is one of the most important sensory features that is used in determining the consumer’s acceptance of a food product [10,11].…”

Section: Introductionmentioning

confidence: 99%

Effect of Microwave Drying on the Drying Characteristics, Color, Microstructure, and Thermal Properties of Trabzon Persimmon

Çelen

2019

Foods

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In this study, changes in the drying kinetics, color change, and the energy consumption for microwave energy were investigated for Trabzon persimmon. In addition to that, the microstructure of the persimmon was also investigated by considering its thermal changes. It is important to be aware of the purpose of the drying process for determining the drying system. Results of this research showed that 460 W for 7 mm slice thickness depending on energy consumption, 600 W for 5 mm slice thickness depending on drying time, and 600 W depending on color changes were found as suitable drying processes depending on drying conditions. The effective diffusion values varied between 2.97 × 10−8 m2 s−1 and 4.63 × 10−6 m2 s−1. The activation energy values for 5 mm, 7 mm and 9 mm slice thickness were estimated as 32.82, 18.64, and 12.80 W g−1, respectively. The drying time and energy consumption decreased, whereas drying rate increased with an increase in the microwave energy. The number of pores increased compared to structure of fresh sample, and the pores got to be larger for 5 mm slice thickness as the power level increased. Results showed that the applied microwave energy had an important effect on the heating of the material and the change in the microstructure.

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Convective, vacuum and microwave drying kinetics of mallow leaves and comparison of color and ascorbic acid values of three drying methods

Cited by 24 publications

References 25 publications

Drying Characteristics and Processing Parameters for Microwave-Vacuum Drying of Kiwifruit (A ctinidia deliciosa ) Slices

Drying Characteristics and Processing Parameters for Microwave-Vacuum Drying of Kiwifruit (A ctinidia deliciosa ) Slices

Phenolic content and some physical properties of dried broccoli as affected by drying method

Effect of Microwave Drying on the Drying Characteristics, Color, Microstructure, and Thermal Properties of Trabzon Persimmon

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