Thermal intermittent drying of apples and its effects on energy consumption

Filippin, Ana Paula; Filho, Lucídio Molina; Fadel, Valmir; Mauro, Maria Aparecida

doi:10.1080/07373937.2017.1421549

Cited by 26 publications

(26 citation statements)

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“…As a result, the specific energy consumption rate decreased. In other words, higher temperature led to larger mass transfer and resulted in lower drying time and reduction in specific energy consumption (Filippin, Filho, Fadel, & Mauro, ). The values of SEC are in agreement with the documented values of 1.197–1.357 kWh for oven drying, 1.107–1.500 kWh for vacuum drying, 1.731–1.961 kWh for US‐vacuum, and 1.571–1.665 kWh for the control applied for green beans (Tekin, Başlar, Karasu, & Kilic, ), 0.17 kWh for CON drying assisted by US of mango Tommy (Mendez‐Calderon, Ocampo‐Castano, & Orrego, ), 20.03 to 56.15 MJ/kg for air‐borne US on fluidized bed drying at different frequencies (20 and 30 kHz) and air temperature (40 to 60°C) of corn kernels (Abdoli et al, ).…”

Section: Resultsmentioning

confidence: 99%

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The effect of microwave and convective dryer with ultrasound pre‐treatment on drying and quality properties of walnut kernel

Abbaspour‐Gilandeh

Kaveh

Jahanbakhshi

2019

J Food Process Preserv

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In this study, the drying kinetics of walnuts was investigated including specific energy consumption (SEC), shrinkage, and walnut kernels' color in two dryers, namely ultrasonic‐convection (US‐CON) and ultrasonic‐microwave (US‐MIC). To carry out this study, walnut samples were dried at three MIC powers (270, 450, and 630 W), three input air temperatures (40, 55, and 70°C) and four duration of ultrasonic pre‐treatment (0 min (control sample), 10, 20, and 40 min). Fifteen mathematical models were used to describe the walnuts' moisture ratio. The results showed that the Midilli et al. model was the best model for describing the process of drying walnuts in US‐CON and US‐MIC dryers. Effective moisture diffusivity (Deff) values were calculated to be between 2.77 × 10–9 and 5.56 × 10–9 m2/s for the US‐CON dryer and 3.12 × 10–9 to 8.99 × 10–9 m2/s for the US‐MIC dryer. The lowest rates of color change were observed in the US‐MIC dryer at the lowest microwave power and the lowest duration of ultrasonic pre‐treatment. The lowest SEC for the US‐CON dryer was 19.52 kWh/kg, and it was 15.90 kWh/kg for the US‐MIC dryer. The highest rate of shrinkage was 14.21%, which was seen in the US‐CON dryer at the air temperature of 70°C and the duration of ultrasonic pre‐treatment of 40 min. According to the results, the best quality of walnut with the lowest changes of color and shrinkage in the microwave dryer was calculated at microwave power 270 W and control sample. Practical applications Drying foods and agricultural products using microwave dryers is a relatively cheap method and has attracted the attention of many researchers today. Also, numerous studies have been conducted on drying agricultural products through microwave and convection dryers with ultrasound pre‐treatment. The result of this study could be applied for gathering comprehensive information regarding the drying process (kinetic, Deff, Ea, and SEC) as well as the qualitative properties (color and shrinkage) of walnut kernels dried using the microwave and convective hot air dryers accompanied by ultrasound pre‐treatment.

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Section: Resultsmentioning

confidence: 99%

“…In other words, higher temperature led to larger mass transfer and resulted in lower drying time and reduction in specific energy consumption (Filippin, Filho, Fadel, & Mauro, 2018). (Abdoli et al, 2018).…”

Section: Ultrasonic-convectionmentioning

confidence: 99%

The effect of microwave and convective dryer with ultrasound pre‐treatment on drying and quality properties of walnut kernel

Abbaspour‐Gilandeh

Kaveh

Jahanbakhshi

2019

J Food Process Preserv

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“…Moreover, a temperature drop during the tempering period is found to reduce the nutrient degradation [16]. It is reported that intermittent dehydration decreased energy consumption in onion by 12% and obtained 17% energy savings in apple drying [17,18]. The ohmic heating of BaTiO3 resistance provides more merits of safety, clarity, and moderation with its resistance of positive temperature coefficient [18][19][20][21][22].…”

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confidence: 99%

Energy Consumption, Colour, Texture, Antioxidants, Odours, and Taste Qualities of Litchi Fruit Dried by Intermittent Ohmic Heating

Cao

Islam

et al. 2020

Foods

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To reduce the cost of dried litchi fruit, the processing characteristics and physicochemical properties of litchi were investigated using drying by intermittent ohmic heating (IOH) (intermittent air drying (IAD)) generated by BaTiO 3 resistance. Litchi fruit pulp were dried at 70 • C with an air velocity of 1.8 m/s; the drying intermittent profiles were as follows: (1) 20 min drying-on and 5 min drying-off; (2) 20 min drying-on and 10 min drying-off; and (3) 20 min drying-on and 15 min drying-off, which correspond to pulse ratios (PRs) of 1.2, 1.5, and 1.8, respectively. After drying, the water content, energy consumption, vitamin C content, total phenolic content, colour, taste, and odour qualities were assessed. The results suggested that IOH drying requires lower energy consumption and yields higher quality products. The energy consumption of intermittent air drying ranged from 341 kJ·g −1 to 427 kJ·g −1 . The IAD of 1.2 and 1.5 PR reduced the browning of litchi fruits and gained better product quality. The major components of odour and tastes were explored in dried litchi. The rising PR of IAD enabled a lower retention of methane and sulphur-organic aroma and a higher assessing value of bitterness taste. This study revealed that BaTiO 3 is suitable for IOH drying and it resulted in more merits of dried litchi fruit.Litchi fruits are mostly processed by air drying with a simple technology of conventional ohmic heating of a chromel-filament [6]. However, conventional ohmic heating (air drying) is shown to have low energy efficiency, take longer, and produce low product quality [11]. Additionally, the continuous ohmic resistant heat of air drying can degrade the antioxidant compounds, colour, flavour, and sensory qualities of litchi fruits [12]. Therefore, it is of great significance to obtain dried product with better colour, odour, nutrition, and low energy consumption in the drying of litchi fruit. However, Song C.F. et al. [6] assessed the sensory qualities of dried litchi fruits and found that the acceptance of dried product is not affected by various drying methods. Intermittent air drying (IAD) is known as an outstanding technique in food drying [12][13][14][15][16]. Intermittent air drying confirmed that IAD decreases the operation cost and increases yields of high-quality fruits and vegetables [13][14][15]. IAD allowed the easy movement of moisture from the interior to the surface of material spontaneously by temperature gradient [15]. Moreover, a temperature drop during the tempering period is found to reduce the nutrient degradation [16]. It is reported that intermittent dehydration decreased energy consumption in onion by 12% and obtained 17% energy savings in apple drying [17,18]. The ohmic heating of BaTiO3 resistance provides more merits of safety, clarity, and moderation with its resistance of positive temperature coefficient [18][19][20][21][22]. Using IOH, the IAD of litchi fruits is expected further to raise the retention of vitamin C and phenolics and to lower energy consumption. Far fewer re...

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“…The drying of fruits with application of the thermal intermittence is based on their high moisture content at the beginning of the drying, whose surface temperature remains lower than the air because of water evaporation. This allows a higher temperature to be initially used and, consequently, reduces the drying time without causing significant damage to the product [2].…”

Section: Introductionmentioning

confidence: 99%

“…For example, Váquiro et al (2009) [5] dehydrated mango slices applying intermittence and obtained increased drying rates and reduced overall operating time, indicating a decrease in energy consumption. However, as foods with high water content are susceptible to many changes due to chemical and biochemical reactions, it is important to evaluate quality through parameters such as color and nutrient retention [2,3].…”

Section: Introductionmentioning

confidence: 99%

Effects of thermal intermittence on fruit characteristics and drying time in convective drying of mango (Mangifera indica L.)

Amado

Silva

Mauro

et al. 2018

Proceedings of 21th International Drying Symposium

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This study investigated the influence of the intermittent drying conditions on drying kinetics and on color and carotenoid retention of mangoes. The drying conditions were 95°C (40 min) and 80°C (40 min) in the first stage combined with 70°C and 60°C in the second stage, and continuous drying (70°C and 60°C) as control. Drying time was reduced by thermal intermittence and carotenoid retention was more affected by temperature than drying time. The results also highlighted the carotenoid sensitivity to 70°C temperature, showing the importance of limiting the temperature of the mango to 60°C during the two drying stages.Effects of thermal intermittence on fruit characteristics and drying time in convective drying of mango (Mangifera indica L.)

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Thermal intermittent drying of apples and its effects on energy consumption

Cited by 26 publications

References 50 publications

The effect of microwave and convective dryer with ultrasound pre‐treatment on drying and quality properties of walnut kernel

The effect of microwave and convective dryer with ultrasound pre‐treatment on drying and quality properties of walnut kernel

Energy Consumption, Colour, Texture, Antioxidants, Odours, and Taste Qualities of Litchi Fruit Dried by Intermittent Ohmic Heating

Effects of thermal intermittence on fruit characteristics and drying time in convective drying of mango (Mangifera indica L.)

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