Dielectric Properties of Pistachio Kernels as Influenced by Frequency, Temperature, Moisture and Salt Content

Ling, Bo; Hou, Lixia; Li, Rui; Wang, Shaojin

doi:10.1007/s11947-014-1413-8

Cited by 48 publications

(18 citation statements)

References 53 publications

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“…Ling et al . 25 also found similar patters at various salt levels. Therefore, it is extremely necessary to take into account the DPs of foods which depend on their salt content in order to design successful RF heating processes.…”

Section: Discussionsupporting

confidence: 54%

“…4). Since pistachio kernels have an uneven shape and cannot make complete contact with the flat electrode, the samples were ground for using this parallel plate method 25,49 . Briefly, the precision impedance analyzer was manually calibrated with a 100 Ohm resistor (04294-61001; Keysight Technologies), and then a predetermined maximum amount of ground sample corresponding to the sample capacity was placed into the test fixture in order to investigate only the effect of salt content on DPs due to a fixed density value of 0.42 g/ml.…”

Section: Methodsmentioning

confidence: 99%

“…Ling et al . 25 reported that the DPs of pistachio kernel samples increased with increasing salt content. The similar trends in salmon and sturgeon caviar were also found by Al-Holy et al .…”

Section: Introductionmentioning

confidence: 99%

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Salt content dependent dielectric properties of pistachios relevant to radio-frequency pasteurization

Jeong¹,

Ryu

Kang

2019

Sci Rep

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This study was conducted to investigate the effect of salt content during radio-frequency (RF) heating on rate of temperature increase, dielectric properties (DPs), and reduction of pathogens in pistachios. Also, the effect of RF heating on pistachio quality of varying salt content was determined. Pistachios of different salt content (0, 100, and 330 mg sodium/serving) were inoculated with Salmonella enterica and treated in a 27.12-MHz RF heater. The RF heating rate increased when salt content was in the range of 0–100 mg sodium/serving, but there were no significant (P > 0.05) differences in the rate of temperature rise after salt content reached to 100 mg sodium/serving. Both dielectric constant and dielectric loss factor of pistachios increased with rising salt content. Along with increased salt content, RF treatment time required to reduce this pathogen by 4 log CFU/g decreased first and then remained the same above an upper limit of salt content corresponding to the peak heating rate. RF treatment did not significantly (P > 0.05) cause changes in the color and level of lipid oxidation of pistachios. The results of the current study imply that RF heating may be a potential intervention for inactivating foodborne pathogens in pistachios and that the effect of pasteurization is influenced by dielectric loss factor relative to salt content.

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Section: Discussionsupporting

confidence: 54%

Section: Methodsmentioning

confidence: 99%

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Salt content dependent dielectric properties of pistachios relevant to radio-frequency pasteurization

Jeong¹,

Ryu

Kang

2019

Sci Rep

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“…Zhang et al [23] found that the DP value of peanut kernels decreased with increasing frequency but increased with increasing temperature and moisture content. Ling et al [24] simulated quadratic polynomial equations for the temperature, moisture content, and frequency of non-salted pistachio nuts, according to the DP data measured from 10–4500 MHz at 25 to 85 °C. Jeong et al [25] found that RF heating can potentially inactivate foodborne Salmonella enterica in pistachios and that the inhibitory effect is controlled by the dielectric loss factor relative to the salt content.…”

Section: Introductionmentioning

confidence: 99%

Effects of Moisture, Temperature, and Salt Content on the Dielectric Properties of Pecan Kernels during Microwave and Radio Frequency Drying Processes

Zhang

Cheng

et al. 2019

Foods

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Dielectric properties of materials influence the interaction of electromagnetic fields with and are therefore important in designing effective dielectric heating processes. We investigated the dielectric properties (DPs) of pecan kernels between 10 and 3000 MHz using a Novocontrol broadband dielectric spectrometer in a temperature range of 5–65 °C and a moisture content range of 10–30% wet basis (wb) at three salt levels. The dielectric constant (ε′) and loss factor (ε″) of the pecan kernels decreased significantly with increasing frequency in the radio frequency (RF) band, but gradually in the measured microwave (MW) band. The moisture content and temperature increase greatly contributed to the increase in the ε′ and ε″ of samples, and ε″ increased sharply with increasing salt strength. Quadratic polynomial models were established to simulate DPs as functions of temperature and moisture content at four frequencies (27, 40, 915, and 2450 MHz), with R2 > 0.94. The average penetration depth of pecan kernels in the RF band was greater than that in the MW band (238.17 ± 21.78 cm vs. 15.23 ± 7.36 cm; p < 0.01). Based on the measured DP data, the simulated and experimental temperature-time histories of pecan kernels at five moisture contents were compared within the 5 min RF heating period.

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“…Each group was divided equally into three replicates. After drying, the nuts were packed in bags (0.05 mm × 268 mm × 279 mm) of high-density polyethylene (HDPE) which are used in the commercial preservation of pecans in China; the bags were heat-sealed, and, stored at Shanghai Boxun) at 105 C for 5 hr, and then the sample were moved to a desiccator for 30 min to reduce their temperature to room temperature before they achieved a constant weight.2.3.2 | Determination of dielectric propertiesDielectric properties were measured by Ling's method(Ling, Guo, Hou, Li, & Wang, 2014) with some modifications. Fresh pecan and hickory kernels with an original moisture content of 30% w.b.…”

mentioning

confidence: 99%

Microwave airflow drying of pecans at variable microwave power

Zhang

Ding

et al. 2018

J Food Process Engineering

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In this study, the dielectric properties of two varieties of pecan nuts at different moistures (10–30% w.b.), temperatures (25–85°C) were determined and the effect of microwave (MW) power density (0.8–2.6 W/g) and exposure time (30–300 s) on moisture content of pecan were approximated by response surface analysis. According to a comprehensive assessment of these results, phased varying power design for MW‐assisted air drying (PPMAD) was appropriate designed to dry pecan nuts. The result indicated that the penetration depths of MW at 2,455 MHz to pecan nuts was distributed in the range of 4.05–10.45 cm in terms of different moisture content and temperature. The moderate output power density (1.7 W/g) is an optimized parameter during the primary stage of MW drying. In PPMAD scheme, 1.7 W/g was delivered in first 150 s, followed by cooling 30 s, and 2.6 W/g was applied in the final 120 s. The results showed that the hybrid drying of PPMAD was efficacious, leading to water losses of 19% in pecan and 16% in hickory without affecting their major compositions and sensory qualities. Further preservation showed that the oxidation degree of PPMAD‐dried nuts was lower than that of the control after 90 days of storage. Practical applications Microwave hybrid drying has been reported to process food and provides a significantly increased shelf‐life for fruits and vegetables, such as apples, carrots, oranges, tomatoes, and spinach. There are no literatures focused on the parameter optimization of microwave drying on pecan and hickory during exposure. The present study provide an optimal method of microwave hybrid using a phased varying power design for MW‐assisted air drying which supply a foundation for large‐scale industrial applications of microwave drying.

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Dielectric Properties of Pistachio Kernels as Influenced by Frequency, Temperature, Moisture and Salt Content

Cited by 48 publications

References 53 publications

Salt content dependent dielectric properties of pistachios relevant to radio-frequency pasteurization

Salt content dependent dielectric properties of pistachios relevant to radio-frequency pasteurization

Effects of Moisture, Temperature, and Salt Content on the Dielectric Properties of Pecan Kernels during Microwave and Radio Frequency Drying Processes

Microwave airflow drying of pecans at variable microwave power

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