Rehydration of Dehydrated Foods

Krokida, Magdalini; Philippopoulos, C.J.

doi:10.1081/drt-200054201

Cited by 137 publications

(112 citation statements)

References 44 publications

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“…The ability of food products to reconstitute depends primarily on the internal structure of the dried pieces and the extent to which the water-holding components (e.g., proteins and starch) have been damaged during drying (Krokida and Philippopoulos, 2005). Figure 3 presents the behaviour of the rehydration ratio (RR) as well as the water holding capacity (WHC) for each air-drying temperature studied.…”

Section: Rehydration Indicesmentioning

confidence: 99%

“…It is generally accepted that the degree of rehydration is dependent on the degree of cellular and structural disruption. Since, rehydration of dried plant tissues is composed of three simultaneous processes: the imbibition of water into the dried material, the swelling and finally the leaching of soluble solids from the dried material, the shrinkage that takes place during dehydration prevents rehydration and produces products with lower apparent density and higher porosity (Krokida and Philippopoulos 2005).…”

Section: Rehydration Indicesmentioning

confidence: 99%

“…Structural properties of the product depend on the type of drying, operative variables and food microstructure formed during the process ). In addition, rehydration capacity which is related to water holding capacity can be considered as a measure of the injury to the material caused by drying (Krokida and Philippopoulos 2005).…”

Section: Introductionmentioning

confidence: 99%

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Influence of drying temperature on dietary fibre, rehydration properties, texture and microstructure of Cape gooseberry (Physalis peruviana L.)

et al. 2013

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The effects of air drying temperature on dietary fibre, texture and microstructure of the Cape gooseberry fruits during convective dehydration in the range of 50-90 ºC were investigated. The ratio of insoluble dietary fibre to soluble dietary fibre was higher than 7:1 for all dehydrated samples. At 50 ºC tissue structure damage was evidenced leading to the maximum water holding capacity (47.4±2.8 g retained water/ 100 g water) and the lowest rehydration ratio (1.15±0.06 g absorbed water/g d.m.). Texture analysis showed effects of drying temperatures on TPA parameters. Changes in microstructure tissue were also observed at the studied drying temperatures. Hot air drying technology leads not only to fruit preservation but also increases and adds value to Cape gooseberry, an asset to develop new functional products.

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Section: Rehydration Indicesmentioning

confidence: 99%

Section: Rehydration Indicesmentioning

confidence: 99%

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Influence of drying temperature on dietary fibre, rehydration properties, texture and microstructure of Cape gooseberry (Physalis peruviana L.)

et al. 2013

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“…By example, at 60 °C the required time was about 780 minutes that is almost three times higher than that obtained in the laboratoryscale drier at the same temperature. According to Krokida;Philippopoulos (2005) to maintain an acceptable safety level of dried foods in terms of microbial contamination and oxidation it is desirable to dry the material until moisture ratio lower than 0.15. Figure 2c and 2d present the experimental and simulated kinetic data obtained in the laboratory-scale drier and the oven driers, respectively, for tomatoes cut in slices at 40, 50 and 60 °C.…”

Section: Convective Drying Kineticsmentioning

confidence: 99%

“…The observed changes are due to hardening, movement of soluble solids and retraction (KROKIDA;PHILIPPOPOULOS, 2005). High temperatures or long drying times can cause serious damage to product flavor, color and nutrients, and reduce the rehydration capacity of the dried product (DOYMAZ, 2007;BARRERA;ANDRÉS, 2007;MURATORE et al, 2008;CRUZ;BRAGA;GRANDI, 2012).…”

Section: Introductionmentioning

confidence: 99%

Efeito da temperatura sobre a cinética de secagem e a cor do tomate italiano

Durigon¹,

Mazutti²,

Mossi

et al. 2013

BBR

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This study evaluated the influence of temperature on drying kinetics and color of Italian tomato of sliced and cut into quarters using different dehydration strategies based on laboratory-convective dried and convective oven drier. The mathematical modeling of drying curves and the effective diffusivity were evaluated. It was verified that tomatoes dried in the laboratory-scale drier presented lower drying time. In addition, the drying time of sliced tomatoes were lower than the cut ones. The proposed drying model presented a satisfactory fitting of the experimental data, showing that the use of global kinetic models presents an alternative to predict the drying profiles at different temperature. It was verified that Deff for tomatoes dried in convective laboratory-scale drier were higher than for oven convective drier, in both cuts. The drying time has strong influence in darkening of the sample and it was verified a tendency in increase the red saturation index with the temperature. The best product quality was obtained using convective laboratory-scale drier at lower drying times. The tomato cut in four parts showed characteristics of final product similar to those sliced tomatoes. However, the slices tomato dried at temperature of 60 °C showed less drying time.Keywords: laboratory-scale drier; oven drier; effective diffusivity; color parameters. resumo Este estudo avaliou a influência da temperatura na cinética de secagem e na cor de tomate italiano cortados em fatias e em quarto partes usando diferentes estratégias de desidratação usando secador convectivo em escala piloto e estufa com circulação de ar. A modelagem matemática das curvas de secagem e da difusividade efetiva foram avaliadas. Foi verificado que os tomates secos em secador em escala de laboratório apresentaram um menor tempo de secagem. Além disso, o tempo de secagem dos tomates cortados em fatias foi inferior ao daqueles cortados em partes. O modelo de secagem proposto apresentou um ajuste satisfatório dos dados experimentais mostrando que o uso do modelo de cinética global apresenta uma alternativa para predizer perfis de secagem em diferentes temperaturas. Foi verificado que os valores de difusividade efetiva dos tomates secos em secador em escala de laboratório foram superiores aos daqueles secos em estufa convectiva em ambos os cortes. O tempo de secagem apresentou grande influência no escurecimento das amostras e foi verificado uma tendência ao aumento do índice de saturação vermelho com a temperatura. A secagem no secador em escala laboratorial apresentou melhor qualidade do produto final e menores tempos de secagem. Os tomates cortados em quatro partes apresentaram características semelhantes aos cortados em fatias. Todavia, os tomates cortados em quatro partes secos a 60 °C foram secos em menores tempos.Palavras-chave: secador em escala laboratorial ; estufa; difusividade efetiva; parâmetros de cor. BBR -Biochemistry and Biotechnology Reports

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Drying: Biological Materials

Law

Mujumdar

2009

Encyclopedia of Industrial Biotechnology

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New advancements in biotechnology has made many biotechnological products such as yeast, bacteria, vitamins, enzymes, proteins, carbohydrates, antibiotics, fungi, lysine, blood, plasma, realize in industry and commercial market. Most of these products appear in the form of liquid, suspension, or paste, which require refrigeration for storage. Refrigeration however limits the widespread application of the products mentioned above, as the operating costs and handling of frozen products is high and difficult. As such, dehydration and drying can be deployed to reduce the handling cost, while prolonging the shelf life, retaining the active ingredients activity, maintaining the cell survival and vitality, as well as its physical, textural, sensory, and optical properties. Biotechnological products are heat sensitive. Conventional drying methods for nonbiotechnological products such as hot air drying may damage and denature the product, destroy the cell and active ingredients, cause case hardening and browning. Over the years, freeze‐drying is the most common method used in the drying of some of the biotechnological products mentioned above. However, the operating cost and the drying time of freeze‐drying are comparatively high. As oil prices are skyrocketing and there is no sign that the price will ease in the near future, researchers and scientists have designed, tested, and improved various drying methods in order to improve drying efficiency and performance. This article discusses various conventional drying methods, which are common to the drying of biotechnological products, and describes various advanced drying technologies that give improvements and better performance with reference to drying strategy, drying medium, handling of drying materials, and mode of heat input. These include intermittent drying, pulse combustion drying, impinging stream drying, cyclic pressure vacuum drying, spray‐freeze‐drying, atmospheric freeze‐drying, vacuum fluidized bed drying, low‐pressure spray drying, superheated steam drying, heat pump drying, inert medium drying, supercritical fluid drying, sorption drying, spouted bed drying, jet spouted bed drying, vibrating fluidized bed drying, pulse fluidized bed drying, high electric field drying, and microwave drying. Recent research findings of these drying technologies are given as well.

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Rehydration of Dehydrated Foods

Cited by 137 publications

References 44 publications

Influence of drying temperature on dietary fibre, rehydration properties, texture and microstructure of Cape gooseberry (Physalis peruviana L.)

Influence of drying temperature on dietary fibre, rehydration properties, texture and microstructure of Cape gooseberry (Physalis peruviana L.)

Efeito da temperatura sobre a cinética de secagem e a cor do tomate italiano

Drying: Biological Materials

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