Overview of new techniques for drying biological materials with emphasis on energy aspects

Raghavan, G.S.V.; Rennie, Timothy J.; Sunjka, P.S.; Orsat, Valérie; Phaphuangwittayakul, W; Terdtoon, Pradit

doi:10.1590/s0104-66322005000200005

Cited by 112 publications

(53 citation statements)

References 11 publications

(12 reference statements)

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“…An increase in drying rates with an increase in IR radiation power or intensity has commonly been reported in the literature [7][8][9][10][11][12][13][14][15][16][17][18]. Table 1 summarizes the values of moisture flux density during the constant flux period (N w,c ), critical moisture content (X cr ), and critical drying time (t cr ) for all IR source temperatures (T IR ) investigated in this study.…”

Section: A M B Neto Et Alsupporting

confidence: 53%

“…The increased awareness about environmental degradation has motivated the application of alternative sources of clean energy in drying operations [8]. Within this context, drying using infrared (IR) radiation appears as an interesting method to intensify heat and mass transfer rates, to minimize energy consumption and to preserve quality of coated seeds.…”

Section: Introductionmentioning

confidence: 99%

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Mass Transfer in Infrared Drying of Gel-Coated Seeds

Neto¹,

Marques²,

Prado

et al. 2014

ACES

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In order to contribute for a better understanding of mass transfer in drying of shrinking particles, in this study shrinkage and drying characteristics of sorghum seeds encapsulated into gel-based polymeric matrix were experimentally determined by using infrared (IR) radiation. IR drying of gel coated seeds was carried out at three different temperatures (65˚C, 80˚C and 93˚C). The shrinkage of the individual particles during drying was quantified by means of the volume and surface area changes evaluated from geometric measurements. The product quality was evaluated in terms of the changes of particle density and percent of cracks in gel coating incurred during drying. Surface area and volume of the gel-seed system decreased about 65% and 80% until the end of the process, respectively, stressing the need to take into account the surface area changes to calculate water flux density as function of moisture content and obtain an accurate interpretation of the drying mechanisms well as to include the volume shrinkage in mass transfer models to determine reliable values of moisture diffusivity. The IR drying behavior of gel-coated seeds was then characterized by the presence of three drying periods: heating up, constant moisture flux and falling moisture flux. Accelerated drying of gel coated seeds was obtained by applying higher IR radiation intensities. The effect of IR source temperature on the particle shrinkage was more pronounced at the constant moisture flux period and practically negligible at the decreasing moisture flux period. Neglecting shrinkage of individual coated-seeds during IR drying led to an erroneous absence of constant flux period and overestimation of the mass transfer by diffusion. Apparent density of the particles was greater at lowtemperature IR drying than at high-temperature IR drying. Coated particles keep their original geometry, but a significant cracking of gel coating was observed at rapid drying rate conditions.

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Section: A M B Neto Et Alsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Mass Transfer in Infrared Drying of Gel-Coated Seeds

Neto¹,

Marques²,

Prado

et al. 2014

ACES

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“…As a result there is increasing pressure to reduce energy consumption, particularly in those countries that are signatories to Kyoto protocol. Raghavan et al (2005) indicated that about 34% of the world produce requires artifi cial drying at least for part of the crop.…”

Section: Energy Effi Ciency In Dryingmentioning

confidence: 99%

Recent advances in drying and dehydration of fruits and vegetables: a review

2010

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Fruits and vegetables are dried to enhance storage stability, minimize packaging requirement and reduce transport weight. Preservation of fruits and vegetables through drying based on sun and solar drying techniques which cause poor quality and product contamination. Energy consumption and quality of dried products are critical parameters in the selection of drying process. An optimum drying system for the preparation of quality dehydrated products is cost effective as it shortens the drying time and cause minimum damage to the product. To reduce the energy utilization and operational cost new dimensions came up in drying techniques. Among the technologies osmotic dehydration, vacuum drying, freeze drying, superheated steam drying, heat pump drying and spray drying have great scope for the production of quality dried products and powders.

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“…Microwave drying of okra has also been done (Dadali et al 2007). Raghavan et al (2005) indicated that about 34% of the world produce requires artificial drying. The drying characteristics of okra has been reported by research workers (Gögus and Maskan 1999;Doymaz 2005;Dadali et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Effect of drying temperature and slice size on quality of dried okra (Abelmoschus esculentus (L.) Moench)

Pendre¹,

Nema

Sharma

et al. 2011

J Food Sci Technol

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Okra (Abelmoschus esculentus (L) Moench) is an important vegetable crop of India. Dried okra pods have wide use in snacks and are in great demand for domestic as well as export market. Hence, effect of four slice sizes (1, 2, 3 and 4 cm) and four drying temperatures (50, 60, 70 and 80°C) on quality of hot air dried okra were studied. Okra pods were dried in the form of slices cut across the length at different temperatures. Quality assessment of okra was done on the basis of protein, ascorbic acid and fibre content. Okra slice sizes and drying temperatures affected all the quality parameters significantly (p<0.05). Maximum retention of protein, ascorbic acid and fibre content were found in 2 cm long slices dried at 60°C temperature.

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Overview of new techniques for drying biological materials with emphasis on energy aspects

Cited by 112 publications

References 11 publications

Mass Transfer in Infrared Drying of Gel-Coated Seeds

Mass Transfer in Infrared Drying of Gel-Coated Seeds

Recent advances in drying and dehydration of fruits and vegetables: a review

Effect of drying temperature and slice size on quality of dried okra (Abelmoschus esculentus (L.) Moench)

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