Vacuum-assisted microwave drying characteristics of green bell pepper

Kumar, Vivek; Shrivastava, Shanker Lal

doi:10.7455/ijfs.v6i1.379

“…The details of the drying equipment and drying procedures are explained in our previous publication (Kumar & Shrivastava, 2017b Fresh GBP samples of known weight were taken and their initial apparent volumes were calculated by toluene displacement method (Giri & Prasad, 2006…”

Section: Shrinkage and Apparent Density Measurementmentioning

confidence: 99%

“…The details of the drying equipment and drying procedures are explained in our previous publication (Kumar & Shrivastava, ). The VAM dryer comprised a microwave oven (Samsung; 2.45 GHz, 0.8 kW), a vacuum glass desiccator, a condenser, a vacuum pump all connected by a hose pipe.…”

Section: Theoretical Models For Shrinkage and Rehydrationmentioning

confidence: 99%

“…Hundred grams of fresh cut sample was dried under three levels of microwave power (100, 200, 300 W) and vacuum pressure (200, 400, 600 mmHg). HAD was done in a single layer in a tray drier (60 °C and airflow rates of 1.5 ms −1 ) (Kumar & Shrivastava, ).…”

Section: Theoretical Models For Shrinkage and Rehydrationmentioning

confidence: 99%

“…dried under three levels of microwave power(100, 200, 300 W) and vacuum pressure (200, 400, 600 mmHg). HAD was done in a single layer in a tray drier (60 C and airflow rates of 1.5 ms −1 )(Kumar & Shrivastava, 2017b).Shrinkage ratio and apparent density of HAD and VAM dried GBP samples were evaluated at different moisture contents ranging from 85 to 10% (w.b.). The above properties for both drying methods were compared and correlated with sample moisture content according to the developed models as described by Equation 8.…”

mentioning

confidence: 99%

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Shrinkage and rehydration characteristics of vacuum assisted microwave dried green bell pepper

Kumar

¹

,

Devi

²

,

Panda

³

et al. 2019

J Food Process Engineering

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Green bell pepper was dried under vacuum assisted microwave (VAM) drying conditions. The effect of microwave power (100, 200, 300 W) and vacuum pressure (200, 400, 600 mmHg) were observed on shrinkage and rehydration characteristics of the sample. Shrinkage was modeled as a linear function of volume change of material and its moisture content. A model was proposed where apparent density could be evaluated as a function of product's moisture content. The sample volume in case of VAM drying shrunk by 59 to 78%, while in case of hot air drying, the shrinkage occurred up to 90%. At a given power level of 100 W, equilibrium rehydration values (Req) increased from 5.04 to 5.75 for samples dried at increasing vacuum pressure from 200 to 600 mmHg. Rehydration rate constant decreased correspondingly for samples dried at higher microwave power levels. Higher level of microwave power and vacuum pressure played significant (p < 0.01) role in producing more porous (lesser shrunken) product leading to higher diffusion (and thus better rehydrated product) of water through it. Diffusion coefficient in rehydration was calculated using Fick's second law. The values of “k” and “R2” varied from 1 × 10−3 to 6.4 × 10−3 and 0.986 to 0.999, respectively. Practical applications Shrinkage and rehydration characteristics of dried vegetables are of utmost importance when it comes to culinary preparations, premixes, convenient foods and retention of sensory qualities. The model proposed in the present study will be helpful in evaluating shrinkage as a function of apparent density and moisture content of dried green bell pepper. Several changes such as shape, size, structure, color, bulk density, porosity, and rehydration capacity are induced due to structural alteration in green bell pepper followed by drying. This information could help in safe commercial packaging of dried products. Further, dried green bell pepper must be rehydrated to be used in preparation of foods such as soups, pizzas, stews, casseroles, and many other recipes. Outcome of the current study can also be referred and implemented while accessing the rehydration characteristics of dried and shrunken vegetables.

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“…Again, there may be continuous fluctuation of relative humidity of the drying air during sun drying and the inability to control the drying process [11,12]. With advancement in technology, microwave drying [13], [14], [15] solar [4] infra-red [3] and hot air drying [16], [17], [18] have been used to dry agricultural products.…”

mentioning

confidence: 99%

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2021

International Journal of Chemical and Process Engineering Resea

0

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The effect of sample thickness and temperature on the drying characteristics of okra was investigated using a laboratory moisture analyser (Denver instrument IR-30) at sample thickness of 5mm, 10mm and 15mm and temperatures of 90 o C, 100 o C and 110 o C respectively. The experimental data was fitted into three thin layer mathematical models. The fitness of the experimental data were evaluated using statistical analysis. It was observed that data fitted well with the Page model for the temperatures and sample thicknesses with the highest R2 values of (0.9904, 0.9962, 0.9963); (0.9963. 0.0072, 0.9937); (0.9924, 0.9940, 0.9933) for 5mm-. 15mm thickness at 90oC, 100 o C and 110 o C respectively with the lowest χ2, MBE and RMSE values. Therefore, Page models adequately described the drying characteristics of okra investigated. The effective moisture ratios were observed to increase with temperature and decrease with okra thickness. The activation energies obtained from Arrhenius equation for 5mm, 10mm and 15mm were 108.7KJ/mol, 118.7KJ/mol and 97.8KJ/mol respectively. Contribution/Originality:This study documents the characteristics and kinetics of okra with effect of thickness. INTRODUCTIONAgricultural products such as fresh fruits and vegetables are perishable [1] and difficult to preserve due to their high moisture content and tender texture. This leads to post harvest losses due to deterioration. Also, transportation of such fruits from one place to the other can be cumbersome due to the weight and volume they can occupy. Drying is the most common preservation method for such products [2]. Up till now, a lot of food losses are being experienced due to inadequate preservation, storage and processing techniques The production of okra in Nigeria is seasonal and often times, the fruits get rotten and become wasted as there are no adequate preservation methods especially at the peak production season where large quantities are produced.Okra is highly nutritious and contains several important micronutrients minerals that the body need [3,4]. Okra also contains some elements that are essential for the treatment of certain disease conditions in humans [5].Although the delicacy of okra is in the fresh fruit and it is mostly used fresh to prepare soup, the shelf life is short [4] and cannot be preserved for longer period. Drying of okra is necessary in order to reduce the water content to a reasonable level so as to prevent the growth and production of microorganisms that facilitate deterioration reaction.Drying will also preserve okra for longer period of time and to make it available and affordable at off season [6]. Furthermore removal of moisture through drying will increase the concentration of the nutrients [7,8].

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Drying Characteristics and Kinetics of Okra at Different Thickness

Torubeli¹,

Samuel²,

Gumus³

2021

International Journal of Chemical and Process Engineering Resea

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The effect of sample thickness and temperature on the drying characteristics of okra was investigated using a laboratory moisture analyser (Denver instrument IR-30) at sample thickness of 5mm, 10mm and 15mm and temperatures of 90 o C, 100 o C and 110 o C respectively. The experimental data was fitted into three thin layer mathematical models. The fitness of the experimental data were evaluated using statistical analysis. It was observed that data fitted well with the Page model for the temperatures and sample thicknesses with the highest R2 values of (0.9904, 0.9962, 0.9963); (0.9963. 0.0072, 0.9937); (0.9924, 0.9940, 0.9933) for 5mm-. 15mm thickness at 90oC, 100 o C and 110 o C respectively with the lowest χ2, MBE and RMSE values. Therefore, Page models adequately described the drying characteristics of okra investigated. The effective moisture ratios were observed to increase with temperature and decrease with okra thickness. The activation energies obtained from Arrhenius equation for 5mm, 10mm and 15mm were 108.7KJ/mol, 118.7KJ/mol and 97.8KJ/mol respectively. Contribution/Originality:This study documents the characteristics and kinetics of okra with effect of thickness. INTRODUCTIONAgricultural products such as fresh fruits and vegetables are perishable [1] and difficult to preserve due to their high moisture content and tender texture. This leads to post harvest losses due to deterioration. Also, transportation of such fruits from one place to the other can be cumbersome due to the weight and volume they can occupy. Drying is the most common preservation method for such products [2]. Up till now, a lot of food losses are being experienced due to inadequate preservation, storage and processing techniques The production of okra in Nigeria is seasonal and often times, the fruits get rotten and become wasted as there are no adequate preservation methods especially at the peak production season where large quantities are produced.Okra is highly nutritious and contains several important micronutrients minerals that the body need [3,4]. Okra also contains some elements that are essential for the treatment of certain disease conditions in humans [5].Although the delicacy of okra is in the fresh fruit and it is mostly used fresh to prepare soup, the shelf life is short [4] and cannot be preserved for longer period. Drying of okra is necessary in order to reduce the water content to a reasonable level so as to prevent the growth and production of microorganisms that facilitate deterioration reaction.Drying will also preserve okra for longer period of time and to make it available and affordable at off season [6]. Furthermore removal of moisture through drying will increase the concentration of the nutrients [7,8].

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Vacuum-assisted microwave drying characteristics of green bell pepper

Cited by 6 publications

References 15 publications

Shrinkage and rehydration characteristics of vacuum assisted microwave dried green bell pepper

Shrinkage and rehydration characteristics of vacuum assisted microwave dried green bell pepper

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Drying Characteristics and Kinetics of Okra at Different Thickness

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