Tag Archives: cooling

705-716 D. Baranenko, V. Kolodyaznaya and Y. Broyko
Effect of cold treatment on the amino acid composition of veal
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Effect of cold treatment on the amino acid composition of veal

D. Baranenko*, V. Kolodyaznaya and Y. Broyko

Institute of refrigeration and biotechnologies, ITMO University, 191002, Lomonosova Street 9, Saint-Petersburg, Russia; *Correspondence: denis.baranenko@gmail.com

Abstract:

Veal is a promising raw material for use in the daily diet, as well as for production of functional and dietary foods. However the effect of cold treatment on the amino acid composition of veal has not been sufficiently studied. The aim of this study was the amino acid composition analysis of veal subjected to various variants of cold treatment. The selected material under research was muscle tissue of hip parts from calves, grown in the Leningrad Region, Russia and aged no more than 3 months. Cooling to 4 ± 1°C and rapid freezing to the temperature of minus 18°C at the cooling air temperatures of minus 24°C and minus 35°C were used as variants of cold treatment. Amino acid composition analyses were carried out using precolumn derivatization with phenylisothiocyanate and reversed-phase gradient HPLC on the Shimadzu 20-AD chromatograph with spectrophotometric detection at 254 nm. The results show the effect of cold treatment on the content of free amino acids and total amino acid composition of veal. In many respects changes in amino acid composition are concerned with moisture losses during the refrigerating treatment. The dependence between the change in amino acid content and the structure of its side chain group type is shown. Amino acid score for essential amino acids was calculated and conclusions about changes in biological value of veal protein were made. The obtained data can be used in biological value calculation of the multi-component products and food rations with veal subjected to refrigerating treatment.

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563-574 P. Pikk and A. Annuk
Case study of increasing photovoltaic energy solar fraction in a conventional office building in northern latitudes
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Case study of increasing photovoltaic energy solar fraction in a conventional office building in northern latitudes

P. Pikk* and A. Annuk

Department of Energy Engineering, Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56, EE51014, Tartu, Estonia; *Correspondence: priit.pikk@emu.ee

Abstract:

Current trends in planning office buildings are moving towards reducing primary energy consumption for heating, hot water heating and cooling. Availability of the solar energy resource and the low temperatures in northern latitudes from early spring until autumn provide the possibility to use photovoltaic (PV) energy for heating, cooling and other energy needs. This article calculates the heating, cooling, hot water and electricity demand of an office building with a glass facade of 65% of the total wall area. The calculated annual total energy consumption is 120 kWh m-2. To reduce the heat and electricity consumption from district heating and the power network, PV modules are integrated into the roof and facade and the solar fractions of the PV energy of the four energy loads (heating, cooling, hot water, and electricity) are found. Optimization of the PV module tilt angles on the facade and roof results in the maximum solar fraction for cooling, heating, preparing hot water, and electricity consumption, 98.4%, 32.1%, 71.7%, and 51.6% respectively. For total load, the calculated maximum solar fraction is 49.8%.

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99–106 A. Ploomi, A. Must, E. Merivee, A. Luik and M. Mänd
Electrophysiological characterization of the cold receptors in the ground beetle Pterostichus oblongopunctatus
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Electrophysiological characterization of the cold receptors in the ground beetle Pterostichus oblongopunctatus

A. Ploomi, A. Must, E. Merivee, A. Luik and M. Mänd

Institute of Plant Protection, Estonian Agricultural University, Kreutzwaldi 64, 51014 Tartu, Estonia; e-mail: angela@eau.ee

Abstract:

Several insects possess thermoreceptors, which aid them in feeding and survival. Campaniform sensilla at the tip of antennae of ground beetlePterostichus oblongopunctatus (Fab., 1787) (Coleoptera, Carabidae) show action potentials of the three sensory cells, A-, B- and C-cells, different in their spike amplitudes. Only the A-cell, with the largest spike amplitude, is highly sensitive to temperature fluctuations, showing remarkable changes in its firing rate induced already by changes in temperature of 0.1°C. A-cells respond to a rapid temperature drop with a strong phasic-tonic reaction; larger decreases in temperature evoke higher peak frequency values. Maximum peak frequencies in A-cells, varying from 344–588 Hz in different specimens, are induced by temperature drop of 7.9–15.7°C, whereas temperature rise strongly inhibits impulse activity of the A-cell. Number of action potentials per first second of response of eight beetles’ was very various, from 7 to 210 impulses, induced by temperature drop from 0.1 to 14.6°C, higher temperature decreased the number of impulses. This knowledge serves as prerequisite information for future electrophysiological studies related to different habitat selection of ground beetles’.

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