Microwave and Blanching Pretreatments for Hot Air Drying of Orange-Fleshed Sweet Potato Slices (Ipomoea batatas)

Abano, Ernest Ekow

doi:10.1155/2020/8872429

Cited by 21 publications

(14 citation statements)

References 18 publications

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“…The microwave pretreatment also led to a high pressure difference between the center and the surface of the product and incremented the drying rate; this will enhance the mass transfer, hence shortening the drying time [ 38 ]. Similar results were reported by the other researchers using a convective dryer and various pretreatments for drying blackberry [ 39 ], apple [ 29 ], potatoes [ 31 ], and black mulberry [ 7 ]. According to Figure 1 c,d), ultrasound pretreatment also caused a significant ( p < 0.05) reduction in the drying time, as compared with the blanching pretreatment.…”

Section: Resultssupporting

confidence: 89%

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Optimization and Prediction of the Drying and Quality of Turnip Slices by Convective-Infrared Dryer under Various Pretreatments by RSM and ANFIS Methods

Taghinezhad

Kaveh

Szumny

2021

Foods

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Drying can prolong the shelf life of a product by reducing microbial activities while facilitating its transportation and storage by decreasing the product weight and volume. The quality factors of the drying process are among the important issues in the drying of food and agricultural products. In this study, the effects of several independent variables such as the temperature of the drying air (50, 60, and 70 °C) and the thickness of the samples (2, 4, and 6 mm) were studied on the response variables including the quality indices (color difference and shrinkage) and drying factors (drying time, effective moisture diffusivity coefficient, specific energy consumption (SEC), energy efficiency and dryer efficiency) of the turnip slices dried by a hybrid convective-infrared (HCIR) dryer. Before drying, the samples were treated by three pretreatments: microwave (360 W for 2.5 min), ultrasonic (at 30 °C for 10 min) and blanching (at 90 °C for 2 min). The statistical analyses of the data and optimization of the drying process were achieved by the response surface method (RSM) and the response variables were predicted by the adaptive neuro-fuzzy inference system (ANFIS) model. The results indicated that an increase in the dryer temperature and a decline in the thickness of the sample can enhance the evaporation rate of the samples which will decrease the drying time (40–20 min), SEC (from 168.98 to 21.57 MJ/kg), color difference (from 50.59 to 15.38) and shrinkage (from 67.84% to 24.28%) while increasing the effective moisture diffusivity coefficient (from 1.007 × 10−9 to 8.11 × 10−9 m2/s), energy efficiency (from 0.89% to 15.23%) and dryer efficiency (from 2.11% to 21.2%). Compared to ultrasonic and blanching, microwave pretreatment increased the energy and drying efficiency; while the variations in the color and shrinkage were the lowest in the ultrasonic pretreatment. The optimal condition involved the temperature of 70 °C and sample thickness of 2 mm with the desirability above 0.89. The ANFIS model also managed to predict the response variables with R2 > 0.96.

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Section: Resultssupporting

confidence: 89%

“…The second Fick’s law is related to the mass diffusivity during the descending phase of the drying process, using appropriate boundary conditions, it is possible to solve the Fick’s equation for various geometries. For a thin layer, the Fick equation can be solved by Equation (3) [ 31 ]:

…”

Section: Methodsmentioning

confidence: 99%

Optimization and Prediction of the Drying and Quality of Turnip Slices by Convective-Infrared Dryer under Various Pretreatments by RSM and ANFIS Methods

Taghinezhad

Kaveh

Szumny

2021

Foods

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“…However, the D eff in anchote slices dried at higher temperatures (65°C and 70°C) was increased by blanching and boiling. This is in agreement with the increased D eff with blanching time in drying orange‐fleshed sweet potato slices (Ipomoea batatas) at 70°C (Abano, 2020). The comparatively low moisture diffusivity values of blanched and boiled slices at the drying temperatures 55°C and 60°C could be due to resistance to moisture migration as a result of gelatinization of starch granules that leads to reduced porosity (Falade et al., 2007; Falade & Solademi, 2010).…”

Section: Resultssupporting

confidence: 79%

Drying behavior of anchote (Coccinia abyssinica[Lam.]Cogn.) tuber slices as affected by predrying treatments and drying temperature

Bikila

Tola

Esho

et al. 2021

J Food Process Preserv

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This study was carried out to evaluate the effect of pretreatment and temperature on the drying behavior of anchote (Coccinia abyssinica [Lam.] Cogn.) tuber slices. It was examined by scheming moisture loss during drying process as a function of time. Ten selected thin layer drying models were evaluated based on R 2 , x 2 , and root mean square error (RMSE). Effective moisture diffusivity (D eff ) and energy of activation (E a ) were estimated from the drying data. The result showed that the drying process exhibited a single falling rate. Both pretreatment and temperature affected drying kinetics. Page model was the most suitable model fitting the drying kinetics (R 2 = 0.9934-0.9999). D eff values were ranged in 3.7 × 10 −8 -1.3 × 10 −7 m 2 /s. E a for raw, blanched, and boiled slices were 56.3, 63.6, and 86.1 kJ/mol, respectively.Energy needed to initiate drying process in boiled anchote slices was higher. Novelty impact statement:The drying kinetics of anchote slices exhibited a single falling rate and is affected by pretreatment and drying temperature with optimum temperature of 65°C to attain the intended drying rate for pretreated samples.Activation energy required to initiate the drying process in the pretreated slices was higher compared with the raw. How to cite this article: Bikila AM, Tola YB, Esho TB, Forsido SF. Drying behavior of anchote (Coccinia abyssinica [Lam.]Cogn.) tuber slices as affected by predrying treatments and drying temperature.

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“…The increase in the surface area due to splitting and pulverization may have caused the accelerated drying rate to result in low moisture content associated with these samples. The decrease in drying time and moisture content with an increase in the surface area and air temperature has been reported for other food materials, including orange fleshed sweet potato slices [ 20 ] and cassava chips [ 21 ].…”

Section: Resultsmentioning

confidence: 89%

“…Vitamin C is heat-sensitive and very reactive and degrades mainly by thermal or oxidative means. Oxidative vitamin C degradation primarily occurs due to long drying times arising from increased sample thickness and tough skin, preventing moisture removal from the food product's surface [ 20 ]. Oxidative vitamin C degradation due to the intact samples' long drying times may have caused such declines in ascorbic acid.…”

Section: Resultsmentioning

confidence: 99%

Drying Kinetics and Quality of Whole, Halved, and Pulverized Tiger Nut Tubers (Cyperus esculentus)

Abano

Akanson

Kizzie-Hayford

2021

International Journal of Food Science

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The objective of this study was to provide the optimum drying conditions to produce high-quality dried tiger nuts using hot-air drying. For this, we evaluated the effect of the whole, halved, and pulverized tiger nuts and air temperature (50 to 70°C) on the drying kinetics and quality of tiger nuts. The drying process generally followed a constant rate in the first 3 hours and a falling regime. We found the optimum drying conditions for tiger nuts to be crushed before convective hot-air drying at a temperature of 70°C. At this optimum condition, the predicted drying time, vitamin C content, reducing sugars, browning, brightness, redness, and yellowness was 780 min, 22.9 mg/100 mg dry weight, 157.01 mg/100 g dry weight, 0.21 Abs unit, 56.97, 1.6, and 17.0, respectively. The tiger nut’s reducing sugars increased from the 130.8 mg/100 dry weight in the raw tiger nuts to between 133.11 and 158.18 mg/100 dry weight after drying. The vitamin C degradation rate was highest in the uncut tiger nuts (32-35%) while in the halved and the pulverized samples, it was between 12 and 17%. The crushed samples’ effective moisture removal increased between 5.6- and 6.75-fold at the different air temperatures than that of the intact tiger nuts. The activation energy was 18.17 kJ/mol for the unbroken, 14.78 kJ/mol for the halved, and 26.61 kJ/mol for the pulverized tiger nut samples. The model MR = 0.997 exp − 0.02 t 1.266 + 0.0000056 t was the most suitable thin-layer drying model among the models examined for convective hot-air drying of tiger nuts. It is advisable to crush tiger nut before hot-air drying to produce better-quality flour for making milk beverages, cakes, biscuits, bread, porridge, and tiger nut-based breakfast cereals.

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Microwave and Blanching Pretreatments for Hot Air Drying of Orange-Fleshed Sweet Potato Slices (Ipomoea batatas)

Abstract: Microwave and steam blanching as pretreatments to hot air drying of orange-fleshed sweet potato (OFSP) were studied. The air-drying experiment was performed at constant temperature of 70°C and airflow of 1.0 m/s. The effective moisture diffusivity varied from 1.5 × 10 − … Show more

Cited by 21 publications

References 18 publications

Optimization and Prediction of the Drying and Quality of Turnip Slices by Convective-Infrared Dryer under Various Pretreatments by RSM and ANFIS Methods

Optimization and Prediction of the Drying and Quality of Turnip Slices by Convective-Infrared Dryer under Various Pretreatments by RSM and ANFIS Methods

Drying behavior of anchote (Coccinia abyssinica[Lam.]Cogn.) tuber slices as affected by predrying treatments and drying temperature

Drying Kinetics and Quality of Whole, Halved, and Pulverized Tiger Nut Tubers (Cyperus esculentus)

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