Drying Behaviour and Energy Requirement for Dehydration of White Onion Slices

Revaskar, V. A.; Sharma, G. P.; Verma, Radha Charan; Jain, Sanjay Kumar; Chahar, Vijay Kumar

doi:10.2202/1556-3758.1077

Cited by 6 publications

(9 citation statements)

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“…Dewatered pulp has more surface area than slices (Mudahar et al 1990;EEBPP 1996;Madamba and Bekki 2001;BEE 2004, Kumar Parveen et al 2005Arabhosseini et al 2010;Aversa et al 2010), which aided in higher heat and mass transfer rate for the samples to be dried. The results corroborate with earlier findings (Vergara et al 1997;Sarsavadia et al 1999;Revaskar et al 2007) where osmotic dewatering prior to drying significantly affected the moisture curves. The drying temperature also affected total drying time (Fig.…”

Section: Effect Of Partial Mechanical Dewatering On Drying Characterisupporting

confidence: 92%

“…Thus mechanical dewatering prior to hot air drying had profoundly affected energy consumption. On similar lines, Revaskar et al (2007) had also reported marginal decrease in energy consumption by drying pre-osmosed onion slices due to partial removal of water from the product before drying. Drying air temperature worked synergistically with the predewatering treatment in reducing the energy consumption (Koyuncu et al 2004).…”

Section: Effect Of Partial Mechanical Dewatering On Specific Energy Cmentioning

confidence: 78%

“…The simplest, most economic and conventional method for dehydration of onion is hot air drying. The air drying method is indispensable even though certain problems like shrinkage, poor re hydration and unfavourable changes in colour, texture, flavour and nutritive value may occur (Kaymak-Ertekin and Gedik 2005; Revaskar et al 2007). Moreover, hot air drying demands longer drying time thus a high expense of energy.…”

Section: Introductionmentioning

confidence: 99%

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A less energy intensive process for dehydrating onion

et al. 2013

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Onion powder has an extensive demand and wide application worldwide as flavour additive in convenience foods and medicinal products. Conventionally onion powder is prepared by hot air drying of onion slices followed by grinding. Convective air drying when used alone demands longer drying time and thus has a high expense of energy. As bulk of onion is water (82-87 %), removal of moisture prior to drying can reduce moisture loading on dryer and hence the energy consumption. Keeping this in view, onions were partially dewatered using centrifugal force before convective drying. The effect of partial mechanical dewatering and drying air temperature was studied on drying time, specific energy consumption and onion powder quality (colour and flavour). The combination process was also optimized to achieve increased drying rate and product quality comparable to products obtained using convective drying alone. Onions subjected to 60 % partial mechanical dewatering and hot air drying at 70°C exhibited significantly (p≤0.5) shortened drying time, decreased energy consumption and maintained colour and flavour of the dried product.

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Section: Effect Of Partial Mechanical Dewatering On Drying Characterisupporting

confidence: 92%

Section: Effect Of Partial Mechanical Dewatering On Specific Energy Cmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

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A less energy intensive process for dehydrating onion

et al. 2013

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“…A fit of the moisture content curves versus time to a first order kinetics is also carried out. This model is known as a simple model (exponential) whose mathematical expression is (Krokida et al, 2003;Senadeera et al, 2003;Simal et al, 2005;Vega-Gálvez et al, 2008):…”

Section: Methodsmentioning

confidence: 99%

“…The physical, texture and nutritional characteristics of food products are modified due to heat treatments (Krokida et al, 2000a,b). In this regard, the osmotic treatments, previous to air-drying process (Lewicki et al, 2002;Rastogi et al, 2004;Revaskar et al, 2007) improve the nutritional, sensory and functional characteristics of dehydrated food products. They may even improve the texture and the stability of pigments during the dehydration and storage of dehydrated products.…”

Section: Introductionmentioning

confidence: 99%

Dehydration kinetics of carrots (Daucus carota L.) in osmotic and air convective drying processes

Vila

Romero

Moreira

et al. 2009

Span. j. agric. res.

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This paper presents a kinetic study of osmotic dehydration and air drying with and without osmotic pre-treatment of carrot. Carrot cylinders of different diameters (4.5, 7 and 9 mm) were employed and, osmotic solutions of sodium chloride of different concentrations (17, 22 and 26% w/w) at various process temperatures (25, 35 and 45°C) and contact times (up to 180 min). The water loss (kg kg -1 ) and the solid gain (kg kg -1 ) in the samples increase with temperature and solution concentration increase. These parameters also depend on size (specific area) of the samples. The drying rate (kg water kg -1 dry solid h -1 ) increases with temperature and decreases with the sample diameter. Experimental drying kinetics were fitted satisfactorily to a first order (simple model) kinetics (where the parameter k s ranges from 0.1748 up to 0.6691 h -1 ) and to the Page model [where the parameters k p (h -n ) and n (-) range from 0.1592 and 1.0683 up to 0.6451 and 1.300, respectively] in order to determine the kinetic constants during drying. Osmotic dehydration combined with the air drying has proven to be an interesting method to reduce water in the samples without extreme thermal processes, nevertheless, the drying rate of the samples previously treated during 1 hour with osmotic dehydration decreased about 13%.Additional keywords: air temperature, drying kinetic parameters, sample size, solid gain, water loss. ResumenCinéticas de la deshidratación de zanahorias (Daucus carota L.) en procesos osmóticos y de secado convectivo con aire En este trabajo se ha realizado un estudio cinético de la deshidratación osmótica y del secado con aire sin y con pretratamiento osmótico de la zanahoria. Se utilizaron cilindros de zanahoria de diferentes diámetros (4,5; 7 y 9 mm) y disoluciones osmóticas de cloruro sódico de distintas concentraciones (17, 22 y 26% en peso) a varias temperaturas de proceso (25, 35 y 45°C) y tiempos de contacto (hasta 180 min). La pérdida de agua (kg kg -1 ) y la ganancia de sólidos (kg kg -1 ) en las muestras aumentaron con la temperatura y la concentración de la disolución. Estos parámetros también dependieron del tamaño (área específica) de las muestras. La velocidad de secado (kg kg -1 de sólido seco h -1 ) aumentó con la temperatura y disminuyó con el diámetro de muestra. Se ajustaron los datos experimentales satisfactoriamente a una cinética de primer orden, modelo simple (donde el parámetro k s varía desde 0,1748 hasta 0,6691 h -1 ) y al modelo de Page [donde el parámetro k p (h -n ) y n (-) varían desde 0,1592 y 1,0683 hasta 0,6451 y 1,300, respectivamente] para determinar las constantes cinéticas durante el secado. La deshidratación osmótica combinada con el secado con aire resulta ser un método interesante para reducir el agua de las muestras sin procesos térmicos extremos, sin embargo, la velocidad de secado de las muestras previamente tratadas con 1 hora de deshidratación osmótica disminuye en torno a un 13%.Palabras clave adicionales: ganancia de sólidos, parámetros cinéticos de secado, ...

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Physical-chemical quality of onion analyzed under drying temperature

Djaeni¹,

Arifin²,

Sasongko³

2017

AIP Conference Proceedings

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Abstract. Drying is one of conventional processes to enhance shelf life of onion. However, the active compounds such as vitamin and anthocyanin (represented in red color), degraded due to the introduction of heat during the process. The objective of this research was to evaluate thiamine content as well as color in onion drying under different temperature. As an indicator, the thiamine and color was observed every 30 minutes for 2 hours. Results showed that thiamine content and color were sensitvely influenced by the temperature change. For example, at 50 o C for 2 hours drying process, the thiamine degradation was 55.37 %, whereas, at 60 o C with same drying time, the degradation was 74.01%. The quality degradation also increased by prolonging drying time.

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Drying Behaviour and Energy Requirement for Dehydration of White Onion Slices

Cited by 6 publications

References 0 publications

A less energy intensive process for dehydrating onion

A less energy intensive process for dehydrating onion

Dehydration kinetics of carrots (Daucus carota L.) in osmotic and air convective drying processes

Physical-chemical quality of onion analyzed under drying temperature

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