Quantitative understanding of Refractance Window™ drying

Ortiz-Jerez, Mónica Jimena; Gulati, Tushar; Datta, Ashim K.; Ochoa-Martínez, Claudia I.

doi:10.1016/j.fbp.2015.05.010

Cited by 92 publications

(64 citation statements)

References 29 publications

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“…) depends on the temperature of the heating source, thickness of the plastic sheet being used, food thickness and its moisture content . At higher temperature of the heating source and smaller thickness of the plastic sheet greater percentage of radiation heat transmittance occurs . The authors observed that the Dupont Mylar sheet had a higher percentage of infrared energy wavelength transmittance.…”

Section: Mylar Sheet – Transmissivity To Heating Modementioning

confidence: 98%

“…20 At higher temperature of the heating source and smaller thickness of the plastic sheet greater percentage of radiation heat transmittance occurs. 22 The authors observed that the Dupont Mylar sheet had a higher percentage of infrared energy wavelength transmittance. The prime mode of heat transfer is conduction and its heat flux ranges from 3571 to 8714 W m −2 and radiation plays a very minor role with the heat flux ranging from 79.43 to 110 W m −2 .…”

Section: Mylar Sheet -Transmissivity To Heating Modementioning

confidence: 98%

“…The RW drying process yields better quality products with the help of high water temperatures resulting in both rapid dehydration and quite low product temperatures . Reaction kinetics for quality degradations are time and temperature dependent . The product temperatures during RW drying process were observed to be 77, 64 and 49 °C when water bath temperature was 95, 75 and 55 °C, respectively .…”

Section: Effects Of Temperature Of Water Bath On Rw Dryingmentioning

confidence: 99%

“…An understanding of the mechanism for this method was developed based on the mathematical model by investigating the effect of the optical properties of the plastic sheets (Mylar) which are commonly used in RW drying. 22 The quantity of energy being conducted and radiated in RW drying (Fig. 2) depends on the temperature of the heating source, thickness of the plastic sheet being used, food thickness and its moisture content.…”

Section: Mylar Sheet -Transmissivity To Heating Modementioning

confidence: 99%

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Refractance window drying of fruits and vegetables: a review

Shende

Datta

2018

J Sci Food Agric

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Fruit and vegetable drying to make leather, pestil or powder products is a challenging task. Traditional drying adversely affects the taste, colour, nutritional qualities and preservation of bioactive compounds due to high-temperature exposure of the product. The substitute for traditional drying processes is consequently necessary to impart superior quality and preserve greater nutritional value in processed foods. Refractance window (RW) drying is a thin film drying system having high heat and mass transfer rates that speeds up the rate of drying. Polyester (Mylar), an infrared transparent plastic sheet transmits radiative heat to food during the RW drying process with higher drying rate, more retention of nutrients and low aroma and flavour loss. RW drying is reported to be affected by the thickness of puree or slices and temperature of drying, as thick samples need longer drying time, generate higher water activity, bring changes in colour parameters, experience higher effective diffusion coefficient (D ) and result in lower solubility of powder. RW drying was compared with different drying processes and was observed to have more retention of nutrients and be more economical. RW dried samples were better in terms of colour and textural quality when compared with other traditional drying methods. © 2018 Society of Chemical Industry.

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Section: Mylar Sheet – Transmissivity To Heating Modementioning

confidence: 98%

Section: Mylar Sheet -Transmissivity To Heating Modementioning

confidence: 98%

Section: Effects Of Temperature Of Water Bath On Rw Dryingmentioning

confidence: 99%

Section: Mylar Sheet -Transmissivity To Heating Modementioning

confidence: 99%

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Refractance window drying of fruits and vegetables: a review

Shende

Datta

2018

J Sci Food Agric

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“…Among different treatments, oven and RW with 200 μm Mylar membrane resulted in the least drying time with average durations of 30.94 and 48.11 min, respectively (Table ); the reason of lower processing time for oven drying was homogeneous distribution of hot air throughout the oven chamber and forced convection due to air flow; besides, lower drying time obtained by 200 μm Mylar membrane was due to its lower thickness and, as a consequence, more effective transfer of infrared radiation caused by water vapor and better heat conduction possibility. Ortiz‐Jerez, Gulati, Datta, and Ochoa‐Martínez () proved that the large majority of RW drying process occurs through heat conduction compared with radiation or convection. Pyrex glass caused petal drying through conveying thermal energy, but since its thickness was higher than Mylar membrane, it took longer time to complete the procedure.…”

Section: Resultsmentioning

confidence: 99%

Refractance‐window as an innovative approach for the drying of saffron petals and stigma

Aghaei

Jafari

Dehnad

et al. 2018

J Food Process Engineering

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In this research, the effects of different dryers including refractance‐window (RW) with 200 or 300 μm Mylar membrane, or Pyrex glass and oven drying, and various temperatures of 25, 60, 70, and 80 °C on saffron quality were surveyed. Levels of safranal, crocin, and picrocrocin for saffron stigma and anthocyanin content for saffron petal were considered as the major quality indices and modeling of their drying kinetics was carried out. While for saffron stigma, RW dryer through Pyrex glass surface and higher temperatures (70 and 80 °C) led to the highest contents of picrocrocin, safranal, crocin, for saffron petal, RW dryer through 200 μm Mylar membrane resulted in the maximum anthocyanin content (106.79 mg/L). Meanwhile, our comparison revealed that RW is a more reliable approach to dry saffron stigma while keeping its functional ingredients, that is, coloring, aromatic, and bitterness strength, than previously introduced novel approaches. The best Artificial Neural Networks (ANNs) topologies to predict RW (200 or 300 μm Mylar membrane, or Pyrex glass) or oven drying data for saffron stigma were those networks having feed‐forward backpropagation network type, hyperbolic tangent sigmoid transfer function and one hidden layer with 3, 7, 5, or 4 neurons in it, respectively. Practical applications Saffron is the dried stigmas of flowers called as “Crocus sativus L.” scientifically and “red gold” in the market because of its high value. Our aim of this research was to introduce a suitable alternative for common traditional drying of saffron as refractance‐Window (RW) and suggest appropriate modeling patterns for industrial application of this drying type in real situations. The second aim of this research was to determine the best drying conditions of saffron petal since the major weight of saffron flower is related to its petal, and anthocyanin of petal extracts could be used as a natural colorant in the food industry, but temperature has a substantial impact on anthocyanin stability.

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