Ethanol pre-treatment improves vegetable drying and rehydration: Kinetics, mechanisms and impact on viscoelastic properties

Rojas, Meliza Lindsay; Augusto, Pedro Esteves Duarte

doi:10.1016/j.jfoodeng.2018.03.028

Cited by 78 publications

(77 citation statements)

References 41 publications

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“…As observed in Figure , E samples improve the initial stage of drying. This behavior could be attributed at the Marangoni effect (Silva et al, ), which is based on the surface tension gradient formed between the ethanol remained on samples surface and their water: This effect promotes the water flow from the sample core to the surface, then accelerating the drying process (Rojas & Augusto, ). However, as the drying time passes, the ethanol is vaporized and the water of the sample decrease.…”

Section: Resultsmentioning

confidence: 99%

“…During ethanol pretreatments, some considerations should be observed, once samples simultaneously lose water and solids, as well as they absorb ethanol (Rojas & Augusto, , ; Silva et al, ). Therefore, the sample “moisture” after pretreatments includes both the mass of the remaining water and the gained ethanol, which are considered together as a lumped parameter ( L p ).…”

Section: Methodsmentioning

confidence: 99%

“…A promising technique to accelerate the drying process, preserve physical properties, and sensible food compounds is the use of ethanol pretreatment (Braga, Pedroso, Augusto, & Silva, ; Braga, Silva, Pedroso, Augusto, & Barata, ; Corrêa, Braga, Hochheim, & Silva, ; Corrêa, Rasia, Mulet, & Cárcel, ; Rojas & Augusto, ; Tatemoto, Mizukoshi, Ehara, & Ishikawa, ). Among the possible mechanisms to improve food drying, the Marangoni effect is important, in special considering the capillarity flow (Rojas & Augusto, ; Silva, Braga, & Santos, ). Therefore, based on the ultrasound and ethanol effects, one interesting possibility was their combined application, where the ethanol promoted the water flow through the channels created by ultrasound (Rojas & Augusto, ).…”

Section: Introductionmentioning

confidence: 99%

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Improving the infrared drying and rehydration of potato slices using simple approaches: Perforations and ethanol

Rojas

Silveira

Augusto

2019

J Food Process Engineering

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The objective of this work was use ethanol and perforations as simple approaches to improve the infrared drying and rehydration of potato slices. Perforations were performed to study the effect of promoting routes to capillarity flow, while ethanol was impregnated in the samples to evaluate the effect of Marangoni flow. All pretreatments reduced the drying time compared to control treatment. However, a great time reduction was observed with P + E pretreatment: The synergistic combination of both treatments increased the drying rate in more than four times, reducing both drying time and the necessary energy by 44%. The samples with perforations (P and P + E) increased their rehydration rate as well as the water retention capacity. However, the pretreated samples with ethanol shows poor rehydration properties. Possible mechanisms were discussed. These results show simple approaches to enhance food drying and rehydration.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving the infrared drying and rehydration of potato slices using simple approaches: Perforations and ethanol

Rojas

Silveira

Augusto

2019

J Food Process Engineering

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“…Two cross-current mass fluxes take part in the previously discussed process: a water flux from the rehydrating medium to the product and solutes flux (acids, sugars, vitamins, and minerals) from the product to the medium [8-10]. Powder-water interactions during rehydration are divided into steps: wetting, sinking, dispersing and, when the product is soluble, dissolution [11].The process of rehydration is influenced by the following intrinsic factors, product chemical composition, its microstructure [12], predrying treatment [13,14], dehydration methods [15,16], extrinsic conditions [17,18] such as the composition of rehydrating medium [19,20], temperature [21,22], and hydrodynamic conditions [23].Genetic algorithms (GA) are optimization methods useful in irregular experimental regions. This optimization tool is applied in such ranges as computer programming, forecasting, image recognition, control, optimization of mechanical and electronic systems, data analysis, and production management and engineering [24].…”

mentioning

confidence: 99%

“…The process of rehydration is influenced by the following intrinsic factors, product chemical composition, its microstructure [12], predrying treatment [13,14], dehydration methods [15,16], extrinsic conditions [17,18] such as the composition of rehydrating medium [19,20], temperature [21,22], and hydrodynamic conditions [23].…”

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confidence: 99%

Apple Cubes Drying and Rehydration. Multiobjective Optimization of the Processes

Winiczenko¹,

Górnicki²,

Kaleta³

et al. 2018

Sustainability

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The effect of convective drying temperature (Td), air velocity (v), rehydration temperature (Tr), and kind of rehydrating medium (pH) was studied on the following apple quality parameters: water absorption capacity (WAC), volume ratio (VR) color difference (CD). To model, simulate, and optimize parameters of the drying and rehydration processes hybrid methods artificial neural network and multiobjective genetic algorithm (MOGA) were developed. MOGA was adapted to the apple tissue, where the simultaneous minimization of CD and VR and the maximization of WAC were considered. The following parameters range were applied, 50 ≤ Td ≤ 70 °C and 0.01 ≤ v ≤ 6 m/s for drying and 20 ≤ Tr ≤ 95 °C for rehydration. Distilled water (pH = 5.45), 0.5% solution of citric acid (pH = 2.12), and apple juice (pH = 3.20) were used as rehydrating media. For determining the rehydrated apple quality parameters the mathematical formulas were developed. The following best result was found. Td = 50.1 °C, v = 4.0 m/s, Tr = 20.1 °C, and pH = 2.1. The values of WAC, VR, and CD were determined as 4.93, 0.44, and 0.46, respectively. Experimental verification was done, the maximum error of modeling was lower than 5.6%.

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Combining ethanol pre‐treatment and ultrasound‐assisted drying to enhance apple chips by fortification with black carrot anthocyanin

2020

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BACKGROUND An interesting approach to improve dried foods nutritional properties, functionality, and sensorial attributes, is by taking advantage of pre‐treatments for incorporating components into the food matrix. Based on this, this work studied the incorporation of black carrot anthocyanins in apple tissue by using ethanol (concentrations 0–300 mL L−1) as a pre‐treatment to ultrasound‐assisted convective drying. Samples were pre‐treated in acidified ethanol solutions, with and without anthocyanins, and then dried (50 °C, 1 m s−1) by convective and ultrasound‐assisted convective (21.77 kHz, 20.5 kW m−3) drying. Both the drying process improvement and the obtained product properties were studied. RESULTS The anthocyanins did not influence the drying kinetics. In contrast, time reduction was > 50% by using both ethanol pre‐treatments and ultrasound. Ethanol pre‐treatments decreased the external resistance to mass transfer, while ultrasound decreased both internal and external resistances. The impregnation increased the anthocyanins (above 947%), which were retained after drying. Colour modifications after pre‐treatments and after drying (L*, b*, h° decrease, and a* increase), and antioxidant capacity retention were observed in samples with anthocyanin addition. CONCLUSION The results point that ethanol pre‐treatments and ultrasound application can accelerate drying, and through the natural colouring incorporation during pre‐treatments, the nutritional properties of dried samples were better retained. © 2020 Society of Chemical Industry

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Ethanol pre-treatment improves vegetable drying and rehydration: Kinetics, mechanisms and impact on viscoelastic properties

Cited by 78 publications

References 41 publications

Improving the infrared drying and rehydration of potato slices using simple approaches: Perforations and ethanol

Improving the infrared drying and rehydration of potato slices using simple approaches: Perforations and ethanol

Apple Cubes Drying and Rehydration. Multiobjective Optimization of the Processes

Combining ethanol pre‐treatment and ultrasound‐assisted drying to enhance apple chips by fortification with black carrot anthocyanin

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