Food drying process by power ultrasound

Fuente-Blanco, S. de la; Riera, Enrique; Acosta-Aparicio, V.M.; Blanco-Blanco, Alfonso; Gallego-Juárez, J.A.

doi:10.1016/j.ultras.2006.05.181

Cited by 302 publications

(144 citation statements)

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“…This effect is responsible for the development of microscopic channels, reducing the layer boundary diffusion and increasing the convective mass transfer in food (Povey & Mason, 1998;Tarleton & Wakeman, 1998;Fuente-Blanco et al, 2006). It is known that the mass transfer of water and solutes rates in intercellular spaces or trans-membrane tissues depends on diffusional and/or osmotic mechanisms.…”

Section: Discussionmentioning

confidence: 99%

The effects of ultrasonic pretreatment and structural changes during the osmotic dehydration of the ˈStarkingˈ apple (Malus domestica Borkh)

Rosas-Mendoza

Fernández-Muñoz

Arjona‐Román

2012

Span. j. agric. res.

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During the osmotic dehydration (OD) of fruit, the cell membrane displays a high resistance to mass transfer, thereby reducing the dehydration rate. To reduce thermal damage to cell membranes, alternative methods have recently been introduced to reduce the initial moisture content and/or modify the structure of fruit tissue. The aim of this work was to evaluate the effects of an ultrasound (US) pretreatment for OD on the effective diffusion coefficients and to observe the changes in the molecular structure of 'Starking' apple cubes by Fourier-transform infrared spectroscopy (FTIR) during a 3 h process using a 45°Bx sucrose solution at 60°C. In the pretreatment step, apple samples were immersed in an ultrasonic bath at 45 kHz for 20 min. The effective diffusion coefficients for water (D ew ) and solids (D es ) were calculated from the observed osmotic kinetics according to Fick's second law for the transient state. The solids coefficients were higher than the water coefficients in both processes due to the concentration difference (D e = 7.7 × 10 -9 and 9.7 × 10 -9 m 2 s -1 for OD US ). The structural changes were determined by FTIR by measuring the molecular vibration frequency for sucrose. The 1,500-900 cm -1 region of the infrared spectra was used to monitor the effect of sucrose concentration on fruit structure. We observed that the first bonds formed were C-H and C-O-C stretching (at 920 and 1,129 cm −1 , respectively) in the sucrose skeleton and glycoside bonds among sucrose molecules. The water concentration affected the diffusion coefficient significantly due to its dependence on the physical structure of the food.Additional key words: cavitation; dehydration kinetics; effective diffusion coefficient; molecular structure; solid gain; water loss. Resumen Efectos del ultrasonido y cambios estructurales durante la deshidratación osmótica de manzana (Malus domestica Borkh) 'Starking'Durante la deshidratación osmótica (DO), la membrana celular representa una alta resistencia a la transferencia de masa y reduce la velocidad de deshidratación. Recientemente, para reducir el daño térmico de las membranas, se han considerado métodos alternativos para reducir el contenido de humedad inicial o modificar la estructura del tejido de la fruta. El objetivo de este trabajo fue evaluar el efecto del ultrasonido (US), cuando se usa como pretratamiento a la DO, sobre los coeficientes de difusión efectiva y observar los cambios en la estructura molecular de manzana 'Starking', mediante espectroscopía infrarroja por transformadas de Fourier (FTIR), durante 3 h de proceso con una solución de sacarosa a 45°Bx y 60°C. Como pretratamiento las muestras fueron tratadas en un baño ultrasónico, a 45 kHz por 20 min. Los coeficientes de difusión efectiva para agua (D ew ) y sólidos (D es = 7,7 × 10 -9 y 9,77 × 10 -9 m 2 s -1 para DO US ) fueron calcu-

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Section: Discussionmentioning

confidence: 99%

The effects of ultrasonic pretreatment and structural changes during the osmotic dehydration of the ˈStarkingˈ apple (Malus domestica Borkh)

Rosas-Mendoza

Fernández-Muñoz

Arjona‐Román

2012

Span. j. agric. res.

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“…Among emergent new technologies ultrasound dehydration is very promising (Garcia-perez et al, 2007;Fuente-Blance et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Ultrasound Assisted Osmotic Dehydration as Pretreatment for Hot-air Drying of Carrot

Liu

Chen

et al. 2014

FSTR

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Ultrasound assisted osmotic dehydration (UOD) combined hot-air drying (AD) process was investigated in thisstudy. The influences of operation parameters such as ultrasonic energy density and solution concentration on weight reduction ratio (WRR) were discussed. The effects of UOD on the following AD of carrot slices were also studied.The results showed that ultrasonic energy density and solution concentration have positive and significant effects on WRR. Osmosis dehydration (OD) pretreatment without ultrasound assistance before AD has negative effects on the total processing time and the effective moisture diffusivity. Yet when ultrasound is applied, the increase of ultrasonic energy density could shorten dehydration time of the following AD process and total processing time. UOD prior to AD has positive effects on improving carotenoid content of product and reducing process energy cost. So it's definitely concluded that UOD pretreatment is an effective and complementary method for traditional AD process.Keywords: ultrasound, osmotic dehydration, hot-air drying, carrot IntroductionAt the present time, consumption of dehydrated food has experienced a noticeable increase in its demand on the market.Conventional dehydration methods based on hot-air drying (AD) are widely used in agricultural industry, but they are time-consuming and energy-intensive, and easily deteriorate the quality of the final products (Humberto et al., 2001;Cohen and Yang, 1995).Scientists and technicists are looking for emerging food processing technologies to enable the production of safer, fresher and better quality foods with longer life for local and export markets.Among emergent new technologies ultrasound dehydration is very promising (Garcia-perez et al., 2007;Fuente-Blance et al., 2006).Ultrasonic waves can produce a rapid series of alternative compressions and expansions, in a similar way to a sponge when it is squeezed and released repeatedly (Soria and Villamiel, 2010).The forces involved by this mechanism can be higher than surface tension which maintains the moisture inside the capillaries and microscopic channels of the fruit, and therefore accelerate moisture removal (Mulet et al., 2003). Ultrasonic waves can reduce viscosity (Greguss, 1963), minimize diffusion boundary layer thickness and remove moisture from solid liquid interfaces (Carcel et al., 2007a;Rodrigues and Fernades, 2007). Furthermore, changes in microstructure have been reported after ultrasonic treatments of fruits, which can additionally improve water removal (Fernandes et al., 2008a).Ultrasonic waves are often used to strengthen osmotic dehydration (OD) of food (Carcel et al., 2007b;Riera et al., 2004). Simal et al. (1998) strengthened OD with ultrasound technology, and concluded that both dewater rate and moisture removal ratio increase significantly compared with traditional OD process. Lenart and Auslander (1980) reported that moisture diffusion rate would increase with the rise of ultrasonic power.Yet Floros and Liang (1994) indicated that the rise of moist...

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“…Power ultrasound increases the effective moisture diffusivities at low air velocities but the improvement becomes negligible at high air velocities [58]. A prototype of an ultrasonic dehydration system has been built and studied in [59]. An impedance matching unit was added to the vibrator to be in direct contact with the food.…”

Section: 23mentioning

confidence: 99%

Enhancement of Heat Transfer by Ultrasound: Review and Recent Advances

Legay

Gondrexon

Person

et al. 2011

International Journal of Chemical Engineering

293

129

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This paper summarizes some applications of ultrasonic vibrations regarding heat transfer enhancement techniques. Research literature is reviewed, with special attention to examples for which ultrasonic technology was used alongside a conventional heat transfer process in order to enhance it. In several industrial applications, the use of ultrasound is often a way to increase productivity in the process itself, but also to take advantage of various subsequent phenomena. The relevant example brought forward here concerns heat exchangers, where it was found that ultrasound not only increases heat transfer rates, but might also be a solution to fouling reduction.

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Food drying process by power ultrasound

Cited by 302 publications

References 4 publications

The effects of ultrasonic pretreatment and structural changes during the osmotic dehydration of the ˈStarkingˈ apple (Malus domestica Borkh)

The effects of ultrasonic pretreatment and structural changes during the osmotic dehydration of the ˈStarkingˈ apple (Malus domestica Borkh)

Ultrasound Assisted Osmotic Dehydration as Pretreatment for Hot-air Drying of Carrot

Enhancement of Heat Transfer by Ultrasound: Review and Recent Advances

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