Grain Drying Using Continuous and Pulsed Microwave Energy

Gunasekaran, Sundaram

doi:10.1080/07373939008959934

Cited by 41 publications

(29 citation statements)

References 5 publications

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“…Microwave heating or drying sometimes results in poor quality of the end product (Gunasekaran 1990;Adu and Otten 1996;Warchalewski et al 1998;Funebo and Ohlsson 1998;Krokida et al 2001;Blaszczak et al 2002). One of the serious concerns from heating food in a microwave oven is the incomplete kill of microbes due to uneven temperature distribution (Fung and Cunningham 1980;Carlin et al 1982;Aleixo et al 1985;Rosenberg and Bogl 1987).…”

Section: Major Problems In Microwave Heatingmentioning

confidence: 92%

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Vadivambal

Jayas

2008

Food Bioprocess Technol

418

186

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Use of microwaves has increased largely in the domestic household in the last few decades due to the convenience of using microwave ovens. In the industrial sector, microwave processing is used in some of the unit operations, while it is yet to capture a major place in the industrial applications. The major drawback associated with microwave heating is the non-uniform temperature distribution, resulting in hot and cold spots in the heated product. The non-uniform temperature distribution not only affects the quality of the food but also raises the issue of food safety when the microorganisms may not be destroyed in the cold spots. The temperature distribution during microwave heating has been studied in a wide variety of products by several researchers. This paper summarizes their results and the solutions offered by them to lessen the nonuniformity of heating. The current applications of microwave energy in the industrial sector are also highlighted.

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Section: Major Problems In Microwave Heatingmentioning

confidence: 92%

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Vadivambal

Jayas

2008

Food Bioprocess Technol

418

186

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“…1995;Raghavan & Venkatachalapathy, 1998). It has been proven that proper control of drying conditions (strength of electric field, airflow rate and inlet temperature), can result to products of quality characteristics equivalent to those of conventionaly air dried materials (Otfen and St. John, 1988;Gunasekaran, 1990;Caldas, 1992;Shivhare et al, 1992Shivhare et al, , 1994Turner & Jolly, 1991). Applying microwave energy under vacuum combines advantages of both vacuum drying and microwave drying as far as improved energy efficiency and product quality are concerned (Anon, 1988;Wadswotth el al., 1990;Yongsawatdigul & Gunasekaran, 1996).…”

Section: Introductionmentioning

confidence: 99%

Drying Related Properties of Apple

Krokida¹,

Kiranoudis²,

Maroulis³

et al. 2000

Drying Technology

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Drying related properties of apple are evaluated for various different drying methods (namely, convective, vacuum, microwave, osmotic and fieeze drying). and their corresponding process conditions. The examined properties are drying kinetics, equilibrium material moisture: content, density, porosity, color and viscoelastic characteristics. The effect of various process factors on these properties is described through particular mathematicall models. The rnodel parameters are estimated by fitting the corresponding model equaltions on a wide range of experimental data. Drying kinetics is greatly affezted by the characteristic particle size and drying air temperature for convective drying., while for the case of microwave drying they are affected by the vacuum pressure and the emitted radiation powex. Equilibrium material moisture content is affected by the temperature and the l~urnidity of the surrounding air, while the osmotic pretreatment shifts the sorption isothmms to higher water activity levels. The quality properties examined, are significantly affected by the drying method. More specifically, osmotic (dehydration decreases the porosity of the final product, while it prevents color deterioration and enchances the viscous nature of dehydrated apple. Freeze-dried apples develop the highest porosity, have the most elastic structure and the lowest rate of color deterioration.

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“…These combined methods are reported to have good potential for high speed and high quality drying. Microwave assisted convective dehydration has been found to be successful for some food products like corn (Gunasekaran 1990), grapes (Tulasidas et al 1993), potato (Bouraoui et al 1994), banana (Maskan 2000), carrot cubes (Prabhanjan et al 1995), button mushroom (Kar et al 2004), garlic (Sharma and Prasad 2001), various medicinal plants (Ren and Chen 1998), apple (Zhenfeng et al 2010), pineapple (Botha et al 2011), etc. It has been observed that the final product has a better color and rehydration ratio.…”

mentioning

confidence: 99%

Standardization of process parameters for microwave assisted convective dehydration of ginger

et al. 2011

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Ginger (Zingiber Officinale, Cv. Suprava) slices (4 mm thick) were dehydrated at 25°, 40°, 50°and 60°C with three different microwave power levels, viz. 120, 240, and 360 W in microwave assisted convective dryer up to 0.07 g moisture/g dry solid to observe the feasibility of microwave assisted convective drying for ginger. The samples were also dried without application of microwaves (0 W) at the above air temperatures. The final product quality was compared in terms of rehydration characteristics, oleoresin and volatile oil contents, hardness, color and organoleptic quality. The maximum rehydration ratio of 3.86±0.06 was obtained at 50°C without application of microwaves and was followed by 120 W-40°C combination treatment (3.64±0.15). The minimum rehydration ratio was 2.34±0.20 for 360 W with 60°C. The yield of oleoresin content was higher for 120 W as compared to other power levels, which ranged between 5.12±0.85% and 6.34±0.89%. The maximum retention of oleoresin was observed in case of 120 W-40°C. The samples dried with microwave power level of 120 W also gave better yields of volatile oil as compared to other power levels. The best color was observed at 120 W-50°C and 120 W-60°C conditions with Hunter 'a' (redness) values at 0.50±0.03 and 0.35±0.03, respectively. The sensory analysis also indicated that drying at 120 W-50°C and 240 W-50°C combinations gave the most acceptable quality product. Drying ginger with 120 W-50°C combination helped in a saving of 53% and 44% in drying time as compared to hot air drying at 50°and 60°C, respectively. Drying at 240 W-50°C also gave a reasonably acceptable quality product with a net saving of 91% and 89% in drying time as compared to hot air drying at 50°and 60°C, respectively. However, on the basis of rehydration characteristics, the acceptable process conditions were hot air drying at 50°or 60°C, or with the 120 W-40°C combination.

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Grain Drying Using Continuous and Pulsed Microwave Energy

Cited by 41 publications

References 5 publications

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Drying Related Properties of Apple

Standardization of process parameters for microwave assisted convective dehydration of ginger

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