Dielectric properties of dried vegetable powders and their temperature profile during radio frequency heating

Ozturk, Samet; Kong, Fanbin; Trabelsi, Samir; Singh, Rakesh K.

doi:10.1016/j.jfoodeng.2015.08.008

Cited by 73 publications

(37 citation statements)

References 33 publications

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“…The dielectric properties of usual interest for practical applications are the dielectric constant, ε′, and the dielectric loss factor, ε′′, the real and imaginary parts, respectively, of the complex permittivity relative to free space, ɛ* = ɛ ′ ‐ j ɛ ′′ . Many studies have reported that the dielectric properties of agricultural products and foods, such as fruits (Barba & Lamberti, ; Guo et al ., ; Ling et al ., ), vegetable powders (Ozturk et al ., ), meat (Abidin et al ., ), eggs (Lin et al ., ; Soltani et al ., ), are dependent not only on the frequency of the electric field and the temperature of the materials, but also on their chemical compositions, such as water (Barba & Lamberti, ; Torrealba‐Melendez et al ., ), salt (Wang et al ., ; Zhang et al ., ), protein (Feng et al ., ; Zhu et al ., ), fat (Zhu et al ., ), sugar (Franco et al ., ), alcohols (Khaled et al ., ), and so on.…”

Section: Introductionmentioning

confidence: 98%

Effect of lactose content on dielectric properties of whole milk and skim milk

Liu

Zhu

2018

Int J of Food Sci Tech

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Summary Dielectric properties (dielectric constant ε′ and dielectric loss factor ε′′) of whole milk and skim milk with the lactose content of 4.56–6.44% and 4.57–6.47%, respectively, were measured over the frequency range of 20–4500 MHz at 25 °C using a vector network analyzer. The results showed that ε′ decreased with increasing frequency, and ε′′ changed with V shape and its minimum was noted at about 2000 MHz. Whole milk had lower dielectric properties than skim milk at almost same lactose content and a given frequency. ε′ had weak positive linear relationship with lactose content for whole milk, but had negative linear relationship for skim milk. No matter for which milk, ε′′ had very good negative linear relationship with lactose content below 1000 MHz and had good positive linear relationship above 2300 MHz. The study provides information on developing rapid lactose detector for milk in future.

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Section: Introductionmentioning

confidence: 98%

Effect of lactose content on dielectric properties of whole milk and skim milk

Liu

Zhu

2018

Int J of Food Sci Tech

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“…They are the real and imaginary parts, respectively, of the complex permittivity relative to free space, ε * = ε ′ − jε ″ . Some studies on dielectric properties of food materials and agricultural products, such as alcohols (Khaled, Novas, Gázquez, García, & Manzano‐Agugliaro, ), sugar (Franco, Yamamoto, Tadini, & Gut, ), honey (Guo, Liu, Zhu, & Wang, ), vegetable powders (Ozturk, Kong, Trabelsi, & Singh, ; Zhu & Guo, ), fruits (Barba & Lamberti, ), meats (Castro‐Giráldez, Dols, Toldr, & Fito, ; Tanaka, Mallikarjunan, & Hung, ), eggs (Lin, Zhang, Fang, & Liu, ; Soltani, Omid, & Alimardani, ), and so on, have shown that the dielectric properties are dependent on frequency and temperature. What is more, the dielectric properties also depend on the compositions of food, such as fat (Zhu, Guo, & Liang, ), protein (Zhu, Guo, Kang, Kong, & Zhu, ), water (Barba & Lamberti, ; Torrealba‐Melendez, Sosa‐Morales, Olvera‐Cervantes, & Corona‐Chavez, ), etc.…”

Section: Introductionmentioning

confidence: 99%

Dielectric properties of raw milk as influenced by frequency, salts, and salt contents

Zhu

Liu

2018

J Food Process Engineering

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To understand the effect of salts and salt contents on dielectric properties (dielectric constant ε′ and dielectric loss factor ε″) of milk, dielectric properties of raw cow's milk samples at the total salt content (in mass) of 0.75–0.87%, 0.75–0.93%, and 0.75–0.90% by adding NaCl, MgCl2, and KCl, respectively, were obtained from 19 to 3,000 MHz at 25 °C using an impedance analyzer. The results showed that ε′ decreased with increasing frequency, and ε″ changed with “V” shape and had minimums at about 1,500 MHz. At a given frequency and the same salt addition level in molar, the milk added with NaCl and MgCl2 had the smallest and the biggest ε″, respectively. At about 40 MHz, ε′ had a very good positive linear relationship with the total salt content of milk, whose coefficients of determination were 0.96, 0.98, and 0.95 for NaCl, MgCl2, and KCl, respectively. ε″ increased linearly with increasing total salt contents with the coefficients of determination higher than 0.99 below about 900 MHz and higher than 0.86 above 900 MHz no matter for which salt. Practical applications This work shows that there were linear relationships between dielectric properties and total salt contents. The study is helpful to understand the influence of salts and salt content on dielectric properties of raw cow's milk, and it offers useful information for developing portable salt detector based on dielectric properties in the future.

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“…Food powders are inclined to cake as they are exposed to external compression, and the level of stickiness and caking of food powder is based on the humidity, particle size and composition of the food. [18,35] In this study, the dielectric properties of chili powder increased with temperature, but at different density, this increase didn't present consistent increase rate at different temperature. The trends of dielectric properties changed with density were not as clear as Ozturk et al's research, which may be due to the different range of density.…”

Section: Effect Of Frequency On Dielectric Propertiesmentioning

confidence: 53%

“…Ozturk et al reported that the dielectric properties first increased and then decreased with the density of several powders, including broccoli, chili and onion powder, tapioca flour, and potato starch, at room temperature and 27.12 MHz. [18] This increasing and decreasing dielectric properties with density was attributed to the caking of powders at high pressure. Food powders are inclined to cake as they are exposed to external compression, and the level of stickiness and caking of food powder is based on the humidity, particle size and composition of the food.…”

Section: Effect Of Frequency On Dielectric Propertiesmentioning

confidence: 99%

“…The measured values of C p , R p by the LCR meter were used to calculate the values of dielectric constant and loss factor. [18] However, the dielectric properties of chili powder were only studied in RF spectrum (1 to 30 MHz) at 22°C. To develop pasteurisation protocols based on RF and MW heating of chili powder, the density-, temperature-, and moisture-dependent dielectric properties of chili powder need to be studied.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dielectric properties of chili powder in the development of radio frequency and microwave pasteurisation

Zhou

Chen

et al. 2017

International Journal of Food Properties

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Food products are dielectric materials. The ability to store and dissipate electromagnetic energy of food in dielectric heating is determined by its dielectric properties. To develop pasteurisation protocols based on radio frequency (RF) and microwave (MW) heating of chili powder, dielectric properties of chili powder were measured using an open-ended coaxialline probe and an impedance analyzer over a frequency range from 8 to 3000 MHz. Penetration depth of chili powder was calculated at five selected frequencies. Results showed that the dielectric properties of chili powder decreased with increase in frequency from 8 to 3000 MHz, but increased with increase in moisture content from 4 to 15% (w. b.) and with increase in temperature from 25 to 85°C. Dielectric constant and loss factor of different density samples showed little difference at low temperature, but large difference at high temperature. RF waves have larger penetration depth in chili powder than MW, and therefore could result in better heating uniformity especially for thicker samples during pasteurisation process. Geometry of sample and heating runaway phenomena may also affect the application of RF pasteurisation for foods. The relationship between moisture content, temperature, and dielectric properties of chili powder at 13.56, 27.12, 40.68, 915 and 2450 MHz can be described by third-order polynomial models with high coefficient of determination (R 2 >0.89), which can be used to predict temperature-and moisture-dependent dielectric constant and loss factor of chili powder with high accuracy. ARTICLE HISTORY

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Dielectric properties of dried vegetable powders and their temperature profile during radio frequency heating

Cited by 73 publications

References 33 publications

Effect of lactose content on dielectric properties of whole milk and skim milk

Effect of lactose content on dielectric properties of whole milk and skim milk

Dielectric properties of raw milk as influenced by frequency, salts, and salt contents

Dielectric properties of chili powder in the development of radio frequency and microwave pasteurisation

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