Dielectric properties of starch slurries as influenced by starch concentration and gelatinization

Motwani, Tanuj; Seetharaman, Koushik; Anantheswaran, Ramaswamy C.

doi:10.1016/j.carbpol.2006.04.017

Cited by 45 publications

(26 citation statements)

References 20 publications

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“…10 W). Thermal behavior of starch paste can be explained as a results of increasing of dielectric loss factor ( ε ″) of the paste in comparison with pure water 30. The more microwave energy is absorbed (less is reflected), the more heat is generated and heating rate is higher.…”

Section: Resultsmentioning

confidence: 99%

Environmental friendly polysaccharide modification – microwave‐assisted oxidation of starch

Łukasiewicz¹,

Bednarz²,

Ptaszek³

2011

Starch Stärke

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A “green” method for oxidized starch preparation was presented. Hydrogen peroxide (H2O2) was used as the starch oxidant. Two main types of experiments were investigated: catalytic (by means of sodium tungstate – Na2WO4, the hydrogen peroxide activator) and non‐catalytic processes. The research covers low microwave level synthesis. Ninety and one hundred and ninety watts of microwave power were applied for the samples. All the microwave‐assisted reactions were compared to conventional ones carried out at 80 and 90°C, respectively. Reaction was monitored using manganometric determination of H2O2 consumption during the reaction progress. Obtained reaction products were tested by means of carbonyl and carboxyl group content. Additionally, molecular mass changes were investigated and a preliminary rheological study was done. The observed significant differences in the degree of oxidation (monitored by means of carboxyl and carbonyl group content) as well as the changes in molecular mass of polysaccharide comparing to those found at conventional conditions were showed and discussed.

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Section: Resultsmentioning

confidence: 99%

Environmental friendly polysaccharide modification – microwave‐assisted oxidation of starch

Łukasiewicz¹,

Bednarz²,

Ptaszek³

2011

Starch Stärke

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“…Depending on the heating rate, the gelatinizing reactions of potato starch could take place at various temperature ranges, such as between 50.0 and 80.3 °C (Singh and others 2003), 56 and 95 °C (Sablani ), and 60.4 and 74.5 °C (Chaiwanichsiri and others ). Gelatinization irreversibly changes the mobility of water molecules by converting free water to structure water of the gelatinized starch (Motwani and others ); therefore, the values of ε′ and ε′′ were significantly decreased from those of nongelatinized samples (Feng and others ). Such decreasing patterns of DE properties at high T were not observed from vacuum‐dried sample result because the gelatinization of the potato slices already occurred during vacuum during process at high T .…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy as an Alternative to Determine Dielectric Constant of Potatoes at Various Moisture Contents

Chee

Rungraeng

Han

et al. 2014

Journal of Food Science

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The dielectric (DE) properties, specifically the DE constant (ε') and loss factor (ε''), were measured for vacuum-dried and freeze-dried potato samples at a microwave frequency of 2.45 GHz over a range of different moisture contents (MCs) using a DE probe and also a 2-probe electrochemical impedance spectroscopy (EIS). Third-order polynomial models (ε' = f₁(MC); and ε'' = f₂(MC)) at room temperature were developed for regression analysis. Additionally, at various temperatures (T), biphasic 3rd-order polynomial models (ε' = f₁(MC, T); and ε'' = f₂(MC, T)) were obtained to determine ε' and ε'' as a function of MC and T using measured data. The vacuum-dried potato sample showed a good fitness of ε' and ε'' (R² = 0.95 and 0.96, respectively) to the regression model with the range of MCs from 18% to 80% (w/w), while the freeze-dried potato sample showed a good fitness of ε' and ε'' to the 1st-phase regression model with MC < 50% w/w (R² = 0.95 and 0.96, respectively) and the 2nd-phase regression model with MC > 50% w/w (R² = 0.94 to 0.96). EIS measurements were also used to obtain correlation impedances for ε' and ε'' determined by the DE probe method. The resulted regression analysis meets the demands for simple, rapid, and accurate assessment for transient values of ε' and ε'' of food products during dehydration/drying processes. The EIS method was verified to be a successful alternative to direct measurements of ε' and ε''.

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“…The dielectric properties of the liquid system were measured using a vector network analyzer (E5071C, Agilent, Santa Clara, CA, USA) with an open-ended coaxial line, connected to a dielectric probe (85070E, Agilent, Santa Clara, CA, USA) [14,15]. The probe was first calibrated using three materials, air, water (of known temperature) and metal, to ensure the accuracy of the measurements.…”

Section: Dielectric Measurementsmentioning

confidence: 99%

Microwave-Absorbing Properties of Rice Starch

et al. 2015

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In the food industry, research into the characteristics of microwave-heated materials has focused on dielectric properties. However, the lack of studies on microwave-absorbing properties has hindered the application of microwave technology. The aim of the present study was to investigate the microwave-absorbing properties of rice starch. It should be noted that this was the first time that the improved arch method was used to measure the microwave reflection loss (RL) of the starch dispersion. The results showed that the microwave absorption of the liquid system corresponded to the classical quarter-wavelength resonator model. When the concentration of the native starch was increased from 1% to 30%, the RL decreased from´5.1 dB to´1.2 dB at 2.45 GHz. Therefore, the absorption rate of microwave, γ ab , decreased from 69.1% to 24.1%. At 1.7 to 2.6 GHz, the interference effect of pregelatinization rice starch in an aqueous system on the microwave absorption properties became weak compared to native starch.

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Dielectric properties of starch slurries as influenced by starch concentration and gelatinization

Cited by 45 publications

References 20 publications

Environmental friendly polysaccharide modification – microwave‐assisted oxidation of starch

Environmental friendly polysaccharide modification – microwave‐assisted oxidation of starch

Electrochemical Impedance Spectroscopy as an Alternative to Determine Dielectric Constant of Potatoes at Various Moisture Contents

Microwave-Absorbing Properties of Rice Starch

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