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Chemical composition of new type agar jellies with Jerusalem artichoke syrup
2012
Kronberga, M., Latvia Univ. of Agriculture, Jelgava (Latvia) | Karklina, D., Latvia Univ. of Agriculture, Jelgava (Latvia)
One of the causes of cardiovascular diseases and overweight problem is a high consumption of sweets. Sugar is traditional food sweet matter. A change of sugar may therefore both change the perception of texture of products. The aim of the research was to evaluate properties of agar-agar jellies prepared with Jerusalem artichoke (Helianthus tuberosus L.) syrup (JAS). Soluble dry matter of experimental samples was determined by Mettler Toledo Refracto, separated sugars - by liquid chromatography, and acidity of jellies - by titration with 0.1 M NaOH. The measurements of pH were made by pH-meter Jenway 3510. Determination of vitamins B1 and B2 was made by the AOAC Official Method 986.27 and 970.65. Texture of samples was determined by using a Texture Analyser (Model TA.XT Plus; Stable Micro Systems), by cylindrical probe (P/25). Colour of jellies was evaluated by using Colour Tec-PCM. The results showed that soluble dry matter decreased from 64.5˚ Brix to 57.5˚ Brix, sucrose decreased by 6%, the acidity increased from 7.2 to 17.8˚, and pH values ranged between 3.8 and 4.5. The hardness of the samples decreased from 50.66N to 40.05N by increasing of added JAS concentration. Adding JAS in jelly, the content of vitamins B1 and B2 increased. Lightness “L” fluctuated between 24.26 and 14.60 with increase JAS concentration. The research suggests that different percents of Jerusalem artichoke syrup could be used as sugar substitute. The product becomes healthier, but the gels obtain a darker colour. Therefore it is recommended to look for other version to improve the colour of experimental jellies.
Afficher plus [+] Moins [-]Investigations into the enhancement of cow's milk oxidative stability
2012
Antone, U., Latvia Univ. of Agriculture, Jelgava (Latvia) | Sterna, V., Latvia Univ. of Agriculture, Jelgava (Latvia) | Zagorska, J., Latvia Univ. of Agriculture, Jelgava (Latvia)
The quality and nutritional value of milk and dairy products are considerably influenced by the stability of its constituents. The aim of the present study was to evaluate the possibility of enhancing oxidative stability of cow’s milk fat and vitamin B2 using carrots and palm oil feed supplement CAF 100 as sources of natural antioxidants in cow feed. Milk samples were collected after 25-day period of feed supplementation. The intensity of riboflavin losses during its photo oxidative degradation in sunlight was measured by the fluorometric method. A slight and significant (p is less than 0.05) difference in higher vitamin B2 stability was seen in carrot-supplemented group (TG1) milk, where the losses of vitamin B2 were by 3.01% less compared to CG (CG). The oxidative stability of butter oil samples stored in 60 °C temperature was analyzed by peroxide value (PV) method. The oxidative stability of samples initially affected by light from both trial groups was significantly (p is less than 0.05) higher compared to CG showing the good potential of the cow diet enrichment with carotenoid additives. The longest induction period (larger than 14 days) was observed in CAF-100- supplemented (TG2) cow milk fats, which can be explained by carotenoids and tocopherol presence and its possible synergism in fat protection. The induction periods of the TG1 and CG were 12.03 and 10.97 days, respectively.
Afficher plus [+] Moins [-]Porcine circovirus-2 impact on the morphological sight of pig lymph nodes
2012
Piginka, I., Institute of Food Safety, Animal Health and Environment BIOR, Riga (Latvia) | Birgele, E., Latvia Univ. of Agriculture, Jelgava (Latvia)
The aim of study was to investigate porcine circovirus-2 (PCV2) impact on the morphological sight of pig lymph nodes. The research was carried out in 2010. Three Latvian farms were investigated (from Latgale and Kurzeme) and thirty 5-15 weeks old pigs with clinical signs of Postweanig Multisystemic Wasting Syndrome were selected and observed. Four lymph nodes from each animal for histological and immunohistochemical investigations were taken. Thirty structural parameters of a lymph node were detected on histological slides: visualization of follicle structure, lymphocyte depletion and amount of histiocytic cell infiltration. As a result, changes in lymph nodes with PCV2 antigen were detected in all these structural parameters: increasing amount of PCV2 antigen in pig lymph nodes, but the greatest changes were in the follicles structure in lymph node. The increased amount of PCV2 antigen in lymph node; significantly decreases the amount of lymphocytes and increases the amount of histiocytes in them. Porcine circoviruss-2 in lymph node basically distributes from the lymph node cortex into the medulla, as well the amount of PCV2 antigen in lymph node also increased.
Afficher plus [+] Moins [-]Physical model of tractor implement
2012
Laceklis-Bertmanis, J., Latvia Univ. of Agriculture, Jelgava (Latvia) | Pirs, V., Latvia Univ. of Agriculture, Jelgava (Latvia) | Kronbergs, E., Latvia Univ. of Agriculture, Jelgava (Latvia) | Metla-Rozentals, M., Konekesko Latvija, SIA, Riga (Latvia) | Metla, M., Konekesko Latvija, SIA, Riga (Latvia)
In order to perceive the pressure oscillation in the hydraulic hitch-system of the tractor and oscillation of the whole tractor aggregate at different loads on the hitch-system, a physical model is used. Changing the position of weight on physical implement boom, different moments of inertia were obtained and the appropriate load on the hydraulic hitch-system hydro cylinder. Results of driving experiments on the artificial roughness road present the maximum pressure peak of 220 bar in the tractor hydraulic system when weight was placed on further position, and the driving speed was 8 km hE-1 and tyre pressure was 1.2 bar. At the driving speed of 11.2 km hE-1 and with the same tyre pressure, the hydraulic system pressures reached up to 212 bar. On the weight on the middle position of boom, pressure in the hydraulic hitch-system reached 172 bar at the driving speed of 7.8 km hE-1 and tyre pressure of 1.2 bar, but at the driving speed of 11.2 km hE-1 and at the same tyre pressure, the hydraulic system pressures reached 165 bar. If the weight was placed on nearest position, pressure in the hydraulic hitch-system reached only 85 bar at the driving speed of 7.8 km hE-1 and tyre pressure - 1.2 bar, but at the driving speed of 11.2 km hE-1 and at the same tyre pressure, it was 98 bar. The investigation of the physical tractor-implement model allows the determination of the conformity of the physical model with real harrow implement.
Afficher plus [+] Moins [-]Heterobasidion spp. in Picea abies understory: incidence and impact on radial growth of trees
2012
Gruduls, K., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Gaitnieks, T., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Donis, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Liepa, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
Heterobasidion spp. is an important pathogen in the Northern Hemisphere, causing root and butt rot mainly in conifers. Norway spruce (Picea abies (L.) Karst.) is one of the most common tree species infected by Heterobasidion spp. In Latvia, 22.9% of Norway spruce stumps are infected. Heterobasidion spp. decreases timber quality, but what impact it has on Norway spruce growing in understory of dominant stand is not known. The aim of the study was to evaluate incidence of Heterobasidion spp. on understory Norway spruce in Myrtillosa forest type and impact on radial growth of trees. In autumn of the year 2011 in a sample plot located in forests of Kalsnava district a total number of 258 trees were examined for presence of Heterobasidion spp. Results showed that 54% of examined trees were rotted. In 30% of trees Heterobasidion spp. was detected. It is concluded that Heterobasidion spp. does not impact radial growth on understory Norway spruce trees.
Afficher plus [+] Moins [-]System analysis of productivity and cost of stump extraction for biofuel using MCR 500 excavator head
2012
Lazdins, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Zimelis, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
In the 30ies of the 20th century stump extraction was identified as one of the most prospective technologies of forest sector to secure deliveries of solid biofuel. Now we are returning to the same challenges having the same targets – to secure energy independence and competitiveness of forest sector. MCR 500 is the prototype of combined stump extraction and mounding bucket for caterpillar excavator produced in Latvia by the LSFRI Silava and engineering company Orvi SIA. The device is made for extraction of stumps with diameter up to 50 cm. Additional benefit of the device is its ability to prepare soil for the forest regeneration by making mounds. The article summarizes results of productivity trials of stump extraction using the MCR 500 head and following forwarding of the material. Data from earlier studies are used to characterize comminution and road transport of stumps and chips. In total 3.5 ha were extracted during the studies. A harvested amount of stumps was estimated using biomass equations. It will be updated in further comminution studies. Average stock of extractable biomass (stumps and coarse roots) on the experimental sites was 28 tons ha-1. Productivity of stump extraction was 2.4...3.4 tons per efficient hour. Consumption of efficient time for scarification of soil was 3.4...4.3 hours per ha. Forwarding took 30 min per load (2.6 tons per efficient working hour). Prime cost of chips according to biomass equations is 9.78 Ls LV mE-3, according to expert judgement based harvested stock is 6.38 Ls LV mE-3.
Afficher plus [+] Moins [-]Quality control management problems of wooden product surfaces
2012
Stekelis, K., Latvia Univ. of Agriculture, Jelgava (Latvia)
The added value of woodworks is determined by the surface quality because it is the first one seen and evaluated by the client. In the production process it is quite problematic to evaluate woodworks surface quality because of large production capacity, and the processed material can be instrumentally tested with a definite time shift. In production most frequently the surface quality is evaluated visually, which is not quite precise. At the same time during the mechanical processing of wood noise is caused by cutting tools as they gradually wear out. The same reasons influence the increase of noise and the quality of woodwork surface. The essence of the problem is to analyze the registered increase of the noise level at a definite workplace and simultaneously follow the surface quality of the processed material – roughness and wear-out of the cutting instrument. The objective of the paper is to research the method of the noise level data collecting and application in order to evaluate wooden product surface quality during wood processing by milling machines. It would provide an opportunity to update the management processes of massive woodworks, supervise the surface quality of woodworks, reduce costs and increase the added value.
Afficher plus [+] Moins [-]Research of 'duration of load' effects in timber elements in bending
2012
Brokans, A., Latvia Univ. of Agriculture, Jelgava (Latvia)
The Duration of Load (DOL) effect is the combined influence of the mechanical loading history and climatic history on the strength of materials. DOL effect is one of the most important characteristics of wood and wood-based materials. The material degradation or damage induces strength reductions. Creep is one of the most important effects of DOL. Creep is a phenomenon that negatively affects functional compliance, behaviour and strength of timber structures in extended years of exploitation. The creep phenomenon is affected by surrounding temperature, relative humidity, timber moisture content and other factors. The study aimed to establish a correct factor system for accurate prediction of long-term deformations of timber structures that is corresponding to environmental conditions and timber properties in the region of Latvia. The experimental research was made in Jelgava, Latvia, and represents timber beam four-point long-term loading in bending with variable cross section height-span length ratio under uncontrolled climatic conditions. There were 12 timber beams with two different span lengths – 1.32 m and 1.50 m used. The timber beam cross section dimensions: height – 60 mm, width – 30 mm. The timber beams were not dried and the moisture content at the start of the experiment varied from 19% to 33%. The applied load values – 0.40 kN and 0.31 kN. Moisture content fluctuations and negative air temperature accelerated creep development and intensity. Prediction of final long-term deformations should rate not only the type of timber material and service class but the strength class, too.
Afficher plus [+] Moins [-]Regulated streams rehabilitation using bioengineering methods
2012
Maziliauskas, A., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Baublys, R., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Geguzis, R., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania)
Within several decades many natural Lithuanian rivers were straightened and adapted for needs of soil drainage. By 1998, 63.4 thousands kilometres of trenches of which approximately 46 thousands kilometres were regulated rivers and streams were excavated. It is calculated that trenches of regulated rivers and streams currently cover 82.6, and natural – only 17.4% of total rivers network. While straightening rivers, their channels were extended, their slopes were changed, and bends were removed. Thus, it ensured a fast removal of excess water from drained areas of ground. However, as in the straightened rivers an equal stream was present, unfavourable conditions arouse for ichthyofauna, as well as for settlement and evolution of the invertebrates. Furthermore, possibilities for selfpurification of water running through the channel were reduced. In order to restore morphological, hydraulic, and especially ecological conditions, close to natural ones, of the straightened rivers, it is necessary to renaturalize them. The analysis of river naturalization and renaturalization ways and means was performed on the basis of the reviewed projects carried out in foreign countries. Four renaturalization methods were identified: self-naturalization, soft naturalization, partial and full renaturalisation. The possibility to use these naturalization methods were evaluated taking into account environmental conditions of Lithuania. The analysis of naturalization projects implementation showed that the best way to rehabilitate Lithuania‘s straightened rivers is to use partial renaturalization method that lets form more favourable ecological environment of rivers. The object of the research was - to evaluate the most suitable naturalization methods for Lithuanian conditions.
Afficher plus [+] Moins [-]Churchyard elements in Latgale Upland [Latvia]
2012
Markova, M., Latvia Univ. of Agriculture, Jelgava (Latvia)
Churchyard of Latgale Upland is one of the most important parts of cultural historic space of Latvia. The study is based on the materials from expedition made in summer and autumn 2011, as well as on literary studies. Architecturally compositional form of the church is a key part of the landscape, supplemented by other landscape elements. Research and evaluation of the individual elements give specific cultural space characteristics of each investigated area. Visibility in the main view points and links with residential buildings for the churchyard is vital. Each study of landscape area schemes formation is based not only on the church as a domination point expression. Separate churchyard elements - crucifixes, procession paths, burial area, meditation area and a planting in church gardens - are important in describing churchyards. The aim of the research was to find most common elements in churchyards to establish general guidelines for recording and evaluation of the churchyard in Latgale Upland in future. In perspective that could be used as basis for making the landscape typology. Results showed typical landscape elements in the churchyard. In describing churchyards is important to divide typical and unique elements. The research provides information that is important for the further local territorial development plans, focusing attention on the region’s cultural values and identity preservation.
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