خيارات البحث
النتائج 1141 - 1150 من 2,007
Shelf life extension of fresh sea buckthorn berries (Hippophae rhamnoides)
2006
Seglina, D. | Karklina, D. | Dukalska, L.
Sea buckthorn berries are one of the most important sources of vitamins, minerals, organic acids, polyphenols and other biologically active substances in human nutrition. The shelf life of fresh chilled berries does not exceed one week. The venues of research were Fruit and Berry Processing Centre of the Dobele Horticultural Plant Breeding Experimental Station and Packaging Material Testing Laboratory of the Faculty of Food Technology, Latvia University of Agriculture, from August until October 2005. Two most popular sea buckthorn cultivars in Latvia - 'Avgustinka' and 'Prozrachnaja' - were used for the study. Sea buckthorn samples were packed in ready-made PET/adhesive/PP containers supplied by 'Huhtamaki'. Gas mixture with initial composition of 10% of O2, 10% of CO2, 80% of N2 and ambient air as control were used. Containers were sealed on the packaging equipment 'TECNOVAC Pratica'. Packed sea buckthorn samples were stored at +4+-1 deg C temperature for 50 days. The aim of this study was to clarify the effect of the initial concentration of gas mixture in the package made from plastic of high barrier properties on the quality of fresh sea buckthorn berries during storage time. The results showed that shelf life of fresh sea buckthorn berries without any significant quality changes can be extended till 30 days by packaging in containers with high barrier properties and air ambiance.
اظهر المزيد [+] اقل [-]The chemical composition of ostrich meat
2006
Kivite, J. | Karklina, D.
Several farmers of Latvia have established ostrich substituting traditional animal growing farms. Ostrich meat is frequently described as a healthy alternative to other meat products. Ostrich, a red meat, is even lower in calories, cholesterol and fat than skinless chicken and turkey, while remaining high in the content of iron and protein. The aim of the investigation is to evaluate the chemical composition of frozen ostrich meat obtain in Latvia and compare it with other meats. The samples of meat for experiments were obtained from ostrich meat producers. Moisture content was determined by drying of the samples at 100 deg C to a constant weight (ISO 6406). Protein content was determined by Kjeldahl method (ISO 5983). Fat content was determined by Soxlet extraction method (ISO 6492). The calories in different meats were determined by an approved procedure which includes summing of the calories from fat and from protein. The investigations showed that there were no significant differences between the main components of ostrich meat produced in Latvia and those found in the data in literature. Chemical composition of ostrich meat does not significantly differ from that of other types of meat. The research suggests that ostrich meat can be substituted for beef or chicken in any recipe, including meat-processing products.
اظهر المزيد [+] اقل [-]Determination of tryptophan metabolites in porcine adipose tissue: a preliminary report
2006
Zamaratskaia, G. | Jastrebova, J.
Tryptophan is a precursor for the production of skatole and indole in the large intestine of pigs. Accumulation of these compounds in adipose tissue causes on objectionable odour in meat from entire male pigs. Potential market impact illustrates the importance in developing an accurate method of determining skatole and indole content in adipose tissue. In the present study, a method is described for determination of skatole and indole concentrations by liquid chromatography combined with mass spectrometry (LC-MS) using atmospheric pressure chemical ionization (APCI). The optimization of chromatographic and APCI conditions is reported. This method showed excellent linearity over the concentration range tested (from 10 to 1000 ng mlE-1 of liquefied fat for both skatole and indole).
اظهر المزيد [+] اقل [-]Changes of pH in beer during manufacture process
2006
Cinkmanis, I.
The possibility to use cranberry juice for acidification of water in the process of beer making instead of traditionally used acidifiers is researched in this work. The output of mail extract received from cranberry juice with acidity regulator is 21.84%. Physicochemical parameters of mash and beer have been defined. The developed method is recommendable for beer production at small enterprises and in home environment.
اظهر المزيد [+] اقل [-]Investigations of grey alder (Alnus incana (L.) moench) biomass
2006
Miezite, O. | Dreimanis, A.
In the time of the decrease of global fossil resources storage wood, pulp has an increasing importance as a heat energy source. In Latvia, grey alder stands occupy 189.9 thousand ha with a total growing stock of 31.1 mil. m**3. So far in most of cases grey alder is estimated as a low value tree species, because tree dimensions do not to allow obtain a significant proportion of timber quality wood. The increasing fuel shortage has caused the need for growing grey alder as a bio energy supply. Grey alder has not been analyzed intensive until now, therefore the aim of the investigation is to estimate the stand productivity and or above ground biomass; that could serve as a background for recommendations to establish grey alder stands for energy-wood production. The grey alder biomass is dependent on wood density, but density - on wood moisture. The average newly felled grey alder wood density in April is 0.76+-0.011 g cmE-3, but absolutely dry wood density for trees felled in October, the average value of absolutely dry wood is 0.46+-0.005 g cmE-3, which is 1% more than in the spring, but these relationships are not significant relative moisture demonstrates water content in newly felled wood. Its average value is 54.7+-0.5% in April and 53.5+-0.05% in October. Empirical formulae are worked out for absolutely dry stem and branch biomass
اظهر المزيد [+] اقل [-]The lichenoindicative evaluation of pine natural woodland habitats
2006
Straupe, I. | Donis, J.
The main pine natural woodland habitats (woodland key habitats -WKH) and the importance of their management and monitoring have been described in this paper. The ecological importance of lichen epiphytes in forest ecosystem has been analysed. The lichenoflora and its percental cover features have been described. The exposition of lichen species depending on the cardinal points has been analysed. The paper presents the characteristics of ecological indicators of lichen in the landscape features. The lichenoindicative evaluation and comparison of pine WKH have been carried out.
اظهر المزيد [+] اقل [-]Variability and genetic determination of Scots pine quantitative traits at the age of 32 years
2006
Jansons, A. | Baumanis, I. | Dreimanis, A. | Gailis, A.
Survival, growth (height, diameter at breast height, stem volume, yield) and quality (thickest branch up to 2 meters of tree height, branchiness, and stem straightness in grades) of phenotypically selected Scots pine plus-tree progenies from different regions in Latvia at the age of 32 years have been analyzed. The material was planted in 4 tests in different forest types (Cladinoso-callunosa, Vacciniosa, Hylocomyosa, and Oxalidosa) in Kalsnava, Eastern part of Latvia. Average number of trees per family varied from 11 to 21 (survival 18-35%). Mean height for Scots pine at the age of 32 years was 14.2 -16.3 m, coefficient of variation -10-17%, diameter at breast height - 13.1-17.7 cm, 24-32%, stem volume 0.1-0.2 m**3, 49-64%, diameter of thickest branch at up to 2 meters of tree height - 1.3-1.7 cm, 23%. To secure ability for detection of significant (alpha=0.05) family differences, average number of trees number per family at evaluation age should be at least 24. Narrow sense individual tree heritability (h**2) was 0.11 for stem volume, 0.09 for diameter at breast height, and 0.07-0.11 for diameter of thickest branch up to two meters of tree height.
اظهر المزيد [+] اقل [-]Indications of pupils' competitiveness
2006
Kalnina, I. | Katane, I.
The ongoing globalisation and integration processes increasingly influencing the different social processes, including the situation in labour market have raised up the topicality of the necessity in education to develop competitiveness of the society in general as well as in every individual. Several documents of international and national importance provide evidence for such an assumption. Education is to become preconditions, process, result, and tool for the development of competitiveness of an individual. This promotional process should be based on scientific research as well as become a part of the duties of every educator. Therefore it is important to scientifically substantiate the conceptual notion 'competitiveness', differentiating between its structure, components, and features. The authors of the present paper have found the theoretical background: 1) theoretical substantiation of the concept of competitiveness in the researches by scientists from Western countries and Russia; 2) appropriate definitions of the concept 'competence' for research of pupils' competitiveness.
اظهر المزيد [+] اقل [-]Training academic writing in university students
2006
Luse, N.
Training academic writing is proposed as a topical subject within the teachers' education study programme on graduate level at Latvia University of Agriculture. In order to promote the development of students personality self-actualization, we are called for introducing new digital technology as teaching-learning method contributing to opening up opportunities in training academic writing at University. How can we use the digital environment for developing formal academic writing technique in our students? The main argument is that digital environment is a key factor for changes in the teaching-learning process and organization of Teachers' Education study programme curricula as the traditional academic print world is changed. Students involved in the Teachers' Education study programme at University are using Web conducting their learning process. Academic writing as a part of learning process at University is based on cognition and activity. We propose to define the training of students' academic writing as a learning process transforming the student's knowledge in unity of two positions: curricular academic writing and informal academic writing. We propose three criteria towards the students' academic writing as heuristics, self-dependence and collaboration. How can we help our students to promote academic writing by using the digital environment? How can we help them differentiate between the appropriate and inappropriate use of information found on the Web and understand what plagiarism is and how is to be avoided?
اظهر المزيد [+] اقل [-]Acquisition of some meteorological parameters for the development of solar collectors
2006
Kancevica, L.
In order to get maximum economic effect, when setting a solar collector in a peasant yard, it is important to choose the correct place. The yield of obtained heat energy will be at its maximum, if the temperature of surrounding air and solar radiation are higher by the relative humidity of the air - lower. To define these parameters, a special device 'Meteorological Device' (MD-4) was developed. The device was supplied with a mechanism which tracks the sun all day round. So the direct solar radiation on the surface perpendicular to the sun beams was measured. The second measuring of the solar radiation was made in relation to the surface, which was perpendicular to the sun beams only at the middle of a day time. For the measuring of the air temperature and relative humidity, corresponding sensors were used. In every 15 minutes the data of these four meteorological parameters were automatically measured and the results were saved into a logger - the device for data accumulation. After a certain period of time the information was brought into the memory of a computer and analysed.
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