Authors:M. Szalai, J. Szigeti, L. Farkas, L. Varga, A. Réti, and E. Zukál
The shelf-lives of major commercial cooked meat products (i.e., Bologna sausage, Italian-type cooked sausage, and cooked ham) packaged under vacuum or modified atmospheres were tested in this study. Samples were taken from commercial meat processing lines, sliced to 1.2 mm thickness and placed overlapped into polypropylene trays sealed with plastic films. The headspace of modified atmosphere packaged formulations consisted of 30% CO2 and 70% N2 or 60% CO2 and 40% N2. The samples thus produced were stored under refrigerated conditions. The values of microbiological, chemical, physical or sensory properties were plotted against storage time, and Gompertz curves were fitted to all time series that changed from an initial to a final value during any period of storage. The influence of headspace CO2 concentration on the properties of sliced cooked meat products varied considerably and, therefore, it was not possible to specify general rules. However, the presence of CO2 in the packaging atmosphere slowed down the rate of microbial growth, thereby delaying the spoilage of meat products. A CO2 level of 60% had beneficial effects on both the microbiological and sensory properties of sliced sausages and cooked ham. It was concluded that cooked meat products packaged under modified atmospheres had a shelf-life of 20 days.
Authors:Peter Kapalo, Florin Domnita, and Jan Lojkovics
The aim of the paper is to determine a methodology for calculating the needed airflow rate (including fresh air) in an occupied room, based on carbon dioxide measurement and calculation, in order to maintain the comfort indoor air quality. The calculated airflow rate should optimize the investment and the operating costs of HVAC equipment. In the work there are analyzed the calculation methods used to determine the ventilation airflow rate. It is presented the methodology for calculating the ventilation airflow rate for a room with people inside by using the measured values of carbon dioxide concentration. The connection between carbon dioxide concentration and ventilation airflow rate is verified by experimental measurements. This methodology is applicable in Slovakia because it complies with all current standards. The result obtained by using this calculation method is almost the same with that achieved from experimental measurements. To confirm the results, it is presented a case study of an office with occupants, in which the ventilation airflow rate calculation method is applied.In the article only a part from the total work is presented. The experimental measurements were carried out from 2011 to 2014. Approximately 54 measurements were covering total days or weeks. The following factors have been measured: indoor air temperature, outdoor air temperature, relative humidity of indoor air, relative humidity of outdoor air, concentration of CO2 in indoor air, concentration of CO2 in outdoor air, pressure difference and wind velocity. Ventilation by infiltration was calculated based on these factors using several methodologies. The methodology of measurement is not subject to the article. In this article only one aspect is investigated: CO2 concentration.
Indoor air quality is a major part of indoor environmental quality and plays an important role in creating sustainable and healthy indoor environments. Well-being, health and comfort are affected by indoor air quality. The measurements that are introduced in this research paper were used to record the results of three different residential interiors. These data are a part of a larger scale research project that included the evaluation of residential buildings, offices, university interiors and for instance nurseries. The reason behind conducting the measurements in these interiors was that in all of the examples inadequate indoor air quality and therefore human discomfort, illness and also building failure occurred.
In this paper the theoretical background of the research and the measurement of indoor air quality (indoor air temperature, relative humidity level and carbon dioxide level) will be introduced. The poor indoor air quality in these buildings is a result of a complex system. The thermal bridges of the facade cause cold interior surfaces, the airtight solutions cause high relative humidity levels. These two combined result in mould appearance. Besides, the lack of appropriate ventilation rate can be the third part of the reason behind poor indoor air quality.
Based on the results of the measurement data, different solutions are suggested in each case to improve indoor environmental and air quality, in accordance with creating healthier indoor environments.
Retrofit of the old building stock presents a good possibility to reduce the energy consumption. However, as the envelopes of old buildings become tighter, a risk increases that the fresh outside air supplied to the indoor environment by natural infiltration can decrease below the amounts required for a comfortable indoor environment, especially in buildings where mechanical ventilation has not been installed. This study presents an efficient method to measure the ventilation intensity, demonstrated on a 40-years old high-rise office building after a complete envelope retrofit. The well-established tracer gas decay and tracer gas step-up method were employed to obtain the ventilation intensity, using the natural CO2 produced by the occupants as the tracer gas. The measured values of the air change rate were between 0.1 and 0.7 1/h for the simple façade, whereas it ranged from 0.2 to 0.5 1/h for the double skin façade, with the windows closed. The level of compliance with ventilation requirements varied, depending on the standard and the philosophy adopted.
Authors:D. Vodnik, I. Maček, E. Péli, U. Videmšek, and Z. Tuba
. Kovács, J. Balogh and Z. Tuba. 2003. Anatomical and eco-physiological changes in leaves of couch-grass (
L.), a temperate loess grassland species, after 7 years growth under elevated CO2concentration.