Tag Archives: microwaves

1829-1843 L. Nilova, R. Ikramov and S. Malyutenkova
The possibility of using microwaves to obtain extracts from berry press residues and jelly products with bioactive characteristics
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The possibility of using microwaves to obtain extracts from berry press residues and jelly products with bioactive characteristics

L. Nilova*, R. Ikramov and S. Malyutenkova

Peter the Great St. Petersburg Polytechnic University, Institute of Industrial Management, Economics and Trade, Graduate School of Service and Trade, Novorossiyskaya street 50, RU194021 Saint-Petersburg, Russia
*Correspondence: nilova_l_p@mai.ru

Abstract:

The paper explores the possibility of development a microwave technology for obtaining water extracts from berry press residues (wild bilberries and cranberries as the objects) and jelly products based on them, which will allow using the waste of freshly squeezed juices in business, such as restaurants and catering services. The antioxidant activity (DPPH and FRAP methods), content of phenolic compounds, flavonoids, anthocyanins, ascorbic acid were determined in berries and in berry press residues. The antioxidant activity of bilberry press residues was due to anthocyanins, and the activity of cranberry press residues was due to flavonoids. Using the microwave oven (magnetron power 800 W, frequency 2,450 MHz), water extracts were obtained in the ratio: for cranberries 1.5:10, for bilberries 1:10. The antioxidant activity of extracts depended on the type of berries and was greater in extracts from bilberry press residues. Extracts of bilberries and cranberries and their compositions (sugar-free and sugar-added) with gelatin as a gelling agent were used to produce the jelly products. Combining bilberry and cranberry extracts (70:30) with gelatin makes it possible to obtain jelly products without sugar. Heating of the ready recipe mixture after preliminary swelling of gelatin and without swelling of gelatin was carried out in the microwave oven. The antioxidant activity of jelly products was higher when using bilberry extracts than cranberries. An increase in the antioxidant activity of the extracts led to a slowdown in structure formation, but increased the plasticity of the products.

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2079-2087 Y. Kretova, L. Tsirulnichenko, N. Naumenko, N. Popova and I. Kalinina
The application of micro-wave treatment to reduce barley contamination
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The application of micro-wave treatment to reduce barley contamination

Y. Kretova*, L. Tsirulnichenko, N. Naumenko, N. Popova and I. Kalinina

South Ural State University, School of Medical Biology, Department of Food and Biotechnology, 85 Lenin Avenue, RU454080 Chelyabinsk, Russia
*Correspondence: kretova555@mail.ru

Abstract:

The goal of this work is to study the applicability of ultra high frequency electromagnetic field treatment for decontaminating barley grain used in brewing while preserving its technological properties. The germination rates and/or yield of the treated sample seed were compared with those of the untreated seed germinated under normal conditions. To determine optimal treatment conditions, a two-factor analysis was carried out, taking the mycological state of the grain into account. The heating rate and the duration of electromagnetic exposure were chosen as variables; these values varied from 0.4 to 0.8 °C s-1 and from 30 to 90 s, respectively. It was found that germination of the treated barley seed was increased about 10.1–15.7% compared with that of the untreated seed. The microbial load decreased up to 80%. A heating rate of 0.4 °C s-1 and treatment exposure time of 30 s showed the strongest effect of decontamination while preserving the viability of the barley grain.

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1015–1022 T. Koppel, A. Shiskin, I. Hussainova, H. Haldre and P. Tint
Electromagnetic shielding properties of ceramic spheres coated with paramagnetic metal
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Electromagnetic shielding properties of ceramic spheres coated with paramagnetic metal

T. Koppel¹*, A. Shiskin², I. Hussainova¹, H. Haldre³ and P. Tint¹

¹Tallinn University of Technology, Ehitajate 5, EE 12616 Tallinn, Estonia
²Faculty of Material Science and Applied Chemistry, Riga Technical University, 3 Paula Valdena str, LV-1048 Riga, Latvia
³Institute of Environmental Health and Safety, Jaam 14, EE 11615 Tallinn, Estonia
*Correspondence: tarmo.koppel@ttu.ee

Abstract:

 This study utilized a setup of radiofrequency generating and metering instruments to measure the reflective and pass-through properties of the innovative material of paramagnetic metal coated ceramic hollow spheres (MCS). The dimensions of the spherical articles reside around 50–250 μm, the thickness of metal (Cu) coating is 0.5–1.3 μm. The radiofrequency field was of 2.4 GigaHertz (GHz) frequency and radiated towards the material via a waveguide-horn antenna at 100 mWt power output. Two additional waveguide-horn antennas connected to a radiofrequency analyzer measured the reflection and pass-through characteristics of the material. Reflection and pass-through coefficients (from 0 to 1) were calculated to each tested sample. The material was tested at different thicknesses: from single – to multi (up to 5) mono-layers and 5 mm layer in bulk condition of MCS.
The measurement results show insignificant shielding characteristics for 1 to 5 layer thickness samples: pass-through coefficient from 0.96 to 0.92. Noteworthy shielding characteristics were starting to show in case of MCS mixed with graphite emulsion: transmission coefficient dropped to 0.16.
The latter sample demonstrates the prospective shielding characteristics of the material, since most of the radiofrequency radiation was not allowed to pass through the material neither to be reflected, but absorbed within the structure of the material.

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