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The influence of biomass type on quantitative and qualitative indicators of biogas Texto completo
2010
Straume, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
The utilization of traditional fossil fuels (oil, gas) as primary energy resources causes a destabilization of the eco-environmental situation in the world. Latvia has to significantly decrease energy imports from its neighbouring countries. This can be achieved by using high-quality local primary renewable energy sources. One of the solutions is to utilize anaerobic fermentation for biogas production. This process can be ensured by utilizing manure, food waste as well as energy biomass - wood, grass and maize. Biogas is utilized as a primary energy source in a cogeneration plant which is a combined cycle plant for electricity and heat power production. Microcogeneration plant for farming household needs would ensure an independent power supply, in case the overall electrical network is in a state of emergency. In order to ensure optimal biogas yield, which, in turn, would ensure a stable operation of the microcogeneration plant, it is important to know the parameters and quality of the biomass that have been filled in bioreactor. This research deals with the influence of the linkage biomass type on the qualitative and quantitative indicators of biogas. As a result, it has been found that biomass type affected the methane percentage in biogas greatly. The methane content of biogas independent with biomass type was diminished from 65% (galega) to 44.5% (fresh sawdust), but biogas yield decreased from 0.627 m**3 kgVSd E-1 (galega) to 0.185 m**3 kgVSd E-1 (fresh sawdust).
Mostrar más [+] Menos [-]Diversity of Lactobacillus spp. in Krievijas cheese Texto completo
2010
Mikelsone, A., Latvia Univ. of Agriculture, Jelgava (Latvia) | Ciprovica, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
Dairy ecosystems have been developing in thousands of years giving us wonderful collection of different types of cheese varieties. On the other hand, modern technology provokes the loss of variability (Adamberg et al., 2007). The only way to keep biological processes under control is to study physiology of microorganisms, and relationships between them systematically, especially non-starter lactic acid bacteria (NSLAB). The number of non-starter lactic acid bacteria increases during cheese ripening and may constitute a dominant population in the mature cheese. The NSLAB diversity, their metabolism and interactions with starter bacteria have an effect on the ripening process of the cheese. The aim of the present study was to investigate the diversity of Lactobacillus spp. during ripening of Krievijas cheese. The diversity of different profiles varied among the cheese samples matured at different temperatures, and the results indicated a correlation between NSLAB species and aroma development (Miķelsone et al., 2009). A higher metabolism of Lactobacillus curvatus at 12 deg C leads to faster depletion of nutrients and approaching the last two phases of microorganism growth curve. However, in each of the cheeses, the microflora had a tendency to be dominated by one Lactobacillus profile at the end of maturation.
Mostrar más [+] Menos [-]Dynamics of sugars composition in berries Texto completo
2010
Boca, S., Latvia Univ. of Agriculture, Jelgava (Latvia) | Skrupskis, I.A., Latvia Univ. of Agriculture, Jelgava (Latvia) | Dimins, F., Latvia Univ. of Agriculture, Jelgava (Latvia) | Krasnova, I., Latvian State Inst. of Fruit-Growing, Dobele (Latvia)
The major sugars in six cultivars grown in Latvia are analysed. The content of glucose, fructose and sucrose in strawberry, blackcurrant and redcurrant berries was determined by applying the method of high performance liquid chromatography (HPLC). By using the obtained calibration curves, concentrations of diverse sugars were found in the analyzed samples. Fructose or fruit-sugar, the same as glucose, is mainly the source of energy in the human body though it is decomposed faster and easier than glucose. In all the researched berry cultivars, the amount of fructose was the largest, particularly in blackcurrants. Six strawberry, black- and redcurrant cultivars were evaluated as raw materials for industrial production. The investigation involved chemical and sensory analyses of fresh berries. The results indicate that pH and sugars of fresh berries influence their quality. Furthermore, high level of sugar adversely affects taste stability. Taste degradation in berries is parallel to flavour deterioration. It is concluded that the main emphasis should be given to the properties of fresh berries.
Mostrar más [+] Menos [-]Changes in physically-chemical and microbiological parameters of Latvian wild cranberries during convective drying Texto completo
2010
Dorofejeva, K., Latvia Univ. of Agriculture, Jelgava (Latvia) | Rakcejeva, T., Latvia Univ. of Agriculture, Jelgava (Latvia) | Skudra, L., Latvia Univ. of Agriculture, Jelgava (Latvia) | Dimins, F., Latvia Univ. of Agriculture, Jelgava (Latvia | Kviesis, J., Latvian State Inst. of Fruit-Growing, Dobele (Latvia)
The research focuses on the study of physically-chemical and microbiological parameter changes in Latvian wild cranberries during convective drying. The research was accomplished on fresh Latvian wild cranberries. The following quality parameters were controlled during the experiments: moisture content (oven-dry method), content of vitamin C (LVS EN 14130:2003), content of polyphenol (HPLC), preparation of samples for microbiological testing (LVS EN ISO 7218:2007), enumeration of yeasts and moulds (ISO 21527-2:2008(E)), counting of lactic acid bacteria (LVS ISO 13721:1995), and total plate count (LVS EN ISO 4833:2003A). The research detected the following optimal convective drying parameters of wild cranberries: temperature – +50±1 deg C and drying time – 20.3 hours. The moisture content of dried berries equalled to 9.0±0.1%. The content of vitamin C decreased 1.9 times in wild cranberries dried at the temperature of +50±1 deg C compared with the content of vitamin C in non-dried cranberries and was 13.05 mg 100 gE-1 in dry matter. The results of current experiments show, that the content of such polyphenols as gallic, caffeic, and epicatechin acids decreased 9.70, 9.90, and 11.68 times, respectively, during the treatment at temperatures up to +50±1 deg C compared with the initial content of these compounds in non-dried berries. The drying temperature substantially influences the microflora development in cranberries. It is possible to decrease significantly the content of LAB, mould, and fungi in berries provided the drying temperature of the wild cranberries does not exceed +50±1 deg C, thus prolonging the ready product shelf-life.
Mostrar más [+] Menos [-]Physical-chemical evaluation of sous vide cooked parent stock hen breast meat during refrigerated storage Texto completo
2010
Ramane, K., Latvia Univ. of Agriculture, Jelgava (Latvia) | Galoburda, R., Latvia Univ. of Agriculture, Jelgava (Latvia) | Murniece, I., Latvia Univ. of Agriculture, Jelgava (Latvia) | Dukalska, L., Latvia Univ. of Agriculture, Jelgava (Latvia)
The aim of this study was to evaluate physical and chemical changes in sous vide cooked marinated parent stock hen breast meat during refrigerated storage. Sous vide method is suitable for preparation of ready-to-eat meat products satisfying consumer demand for convenience and safety. Meat tenderness is recognized as important quality attribute of meats. The study involved preparation of the raw material, vacuum packaging of the products in polyamide/polyethylene (PA/PE) film pouches, marinating for 20 hours, sous vide cooking and chilling in ice water, followed by storage at 3.0±0.5 deg C. Each sample containing a chicken portion or chicken mix with shredded carrots, sea buckthorn sauce and spices was analysed during storage. Water activity, pH, and moisture were assessed during storage. Hardness (shear force) measurement was used as an instrumental method for meat tenderness evaluation. The differences between two studied products were noted regarding all studied parameters – water activity, pH, moisture content, and hardness. The differences mainly were determined by the properties of carrot and sea buckthorn additive, which generally have higher moisture content and lower pH. The researched parameters were well preserved during refrigerated storage for 28 days.
Mostrar más [+] Menos [-]Grey alder fibreboard processed by modified steam explosion unit Texto completo
2010
Tupciauskas, R., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Gravitis, J., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Belkova, L., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Tuherm, H., Latvia Univ. of Agriculture, Jelgava (Latvia)
Experimental self-binding high-density fibreboard is produced of the grey alder (Alnus incana L. Moench) steam-exploded fibres without addition of synthetic adhesives. Milled grey alder chips are processed in steam-explosion unit by saturated steam under pressure of 3.2 MPa at temperature of 235 deg C for 1 min in a 0.5 l batch reactor. The steam-exploded fibres are pressed at 160 deg C temperature under 8 MPa pressure for 10 min in three steps. Properties, such as density, swelling in thickness, water absorption, bending strength, modulus of elasticity at bending, and internal bonding strength of the studied fibreboard samples are reported. Differences between the raw milled chippings and the exploded fibres are observed by scanning electron microscope. The study is focused on modified technical options of the steam-explosion unit supplied with two containers receiving different kinds of the exploded biomass farther used to obtain the hot-pressed boards. The cascade of the receivers is explained in a presently pending patent. The self-binding high-density fibreboard samples show the following properties comparable to commercial products: density of at least 1.35 g cmE-3, moisture content of 7.2%, swelling in thickness of 8.1%, water absorption of 3.2%, bending strength of 27 N mmE-2, modulus of elasticity of 6,259 N mmE-2, and internal bonding of 0.92 N mmE-2.
Mostrar más [+] Menos [-]Results of black alder (Alnus glutinosa (L.) Gaertn.) improvement in Latvia Texto completo
2010
Gailis, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Jansons, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Black alder wood is suitable for production of high quality veneer and other uses, but doe to its small share in total forest area (3%) in Latvia its genetic improvement have not been a priority. Set of progeny tests, together 22.8 ha, have been established only in the last decade. First of them have reached the age of 8 to 10 years and are suitable for first assessment. Aim of our study was to evaluate potential of improvement of black alder using selection, based on progeny testing. Data from 4 open pollinated progeny tests of phenotypically selected black alder plus trees, located in central part of Latvia, each containing from 15 to 21 families, are evaluated, using breeding value as a criterion. Results reveal that selection of parent trees with the practically possible intensity (10%) yields notable improvement in height at the age of 8 to 10 years: from 10 to 32%. Parent trees of open-pollinated families S9, S14, S16 and 84115 that have superior productivity and above-average quality can be recommended for establishment of second-round seed orchard. Estimates of genetic parameter suggest that selection in black alder trials could be carried out with high accuracy and improvements are possible both in productivity and quality (branch thickness, stem straightness, occurrence of spike knots).
Mostrar más [+] Menos [-]Financing mechanisms for research institutes in the field of agriculture in Latvia Texto completo
2010
Mezeniece, M., Latvia Univ. of Agriculture, Jelgava (Latvia) | Feifere, S., University of Latvia, Riga (Latvia) | Rivza, B., Latvia Univ. of Agriculture, Jelgava (Latvia)
Latvia is a territorially small country with small open economy, and its main and the most competitive recourses are highly educated society and well developed science which is based on research, innovation and modern technologies. To create a well functioning innovation system as a part of knowledge-based economy, several conditions has to be met to insure that all parts of national innovation system effectively work together. This article is dedicated to analysis of financing mechanisms that can be used by research institutes in the field of agriculture in Latvia to ensure sustainable rural development. The research in the field of agriculture in Latvia is mainly performed by the state research institutes and research agencies of Latvia University of Agriculture. To provide favourable environment for development of research and science, there is set legislation framework and financing mechanisms such as base financing from the state budget, state research programmes, European Commission Framework Programmes, and the European Union (EU) Structural Funds assistance. The analysis has shown that support of EU Structural funds has positive impact on number of applied research carried out in research institutes in the field of agriculture in Latvia. EU Structural funds assistance helps to develop fundamental research activities and innovative approach to the science that is one of the preconditions for the development of states' competitiveness. In conclusion, the authors resume that it is necessary to establish a strong link between higher education institutions, research institutes, and entrepreneurs in the process of building effectively working national innovation system.
Mostrar más [+] Menos [-]Innovation capacity - problems and solutions for successful development Texto completo
2010
Lukjanska, R., Riga Technical Univ. (Latvia)
Innovation capacity has to be viewed as a consequence of properly operating innovation system. Well established and functioning innovation system is a result of enhanced by government innovation policy. In comparison with other European Union (EU 27) countries, innovation capacity indicators in Latvia remain low and considerably underperform, reflected in the 'European Innovation Scoreboard 2008', where Latvia took the 30th place among 32 countries. Problems and solutions are illustrated to represent innovation capacity in Latvia. This article consists of the following parts: first - theoretical aspects are selected to describe the essential definition of the analyzed subject. In the second part, experience from abroad is described, at the end – Latvian innovation policy and situation is analyzed and suggestions for further needs are formulated. The main results of analysis show that only a few elements of innovation capacity building are functioning at Latvian enterprises, whose aim is to build a base for the innovation capacity of the country.
Mostrar más [+] Menos [-]Rural-urban and regional approach comparing human values in Latvia Texto completo
2010
Bolinskis, G., Data Serviss, Riga (Latvia) | Butkevics, E., Riga Technical Univ. (Latvia)
Regional development should not be a unified process even for a small country such as Latvia. There is a stereotype that people living in big cities and rural areas differ in their values and behaviour. This study compares the human values of Riga, the Riga district urban area and different rural regions in Latvia. During the last three years - 2007, 2008 and 2009 the survey of 1450 inhabitants showed no substantial difference in peoples' social values; comparing rural and urban locations. Rather, a noticeable difference in human values between people living in different regions of Latvia was observed. It was also observed that the set of values expands in different directions over time, forcing a future increase in fragmentation and segmentation of the population in the country.
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