Уточнить поиск
Результаты 1-7 из 7
The efficiency of different wood coatings against water surface absorption
2021
Iejavs, J., Forest and Wood Products Research and Development Inst., Ltd., Jelgava (Latvia) | Ruluks, O., Forest and Wood Products Research and Development Inst., Ltd., Jelgava (Latvia) | Laiveniece, L., Forest and Wood Products Research and Development Inst., Ltd., Jelgava (Latvia) | Jakovlevs, V., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Pugovics, K., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Lise, S., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Spulle, U., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
In the market of the Latvia different wood surface coating materials suitable for use in outdoor conditions are offered, but available information on the efficiency of these against direct water exposure is insufficient. For structural timber building elements, such as glued laminated timber (GLT), the surface coating should be applied taking into account technological, visual or colour changes (ISO 7724:1984) and – last, but not least – economic aspects are considered. Wood surfaces coated with coating materials, such as varnishes, paints, etc. can stabilize some properties such as movement of moisture content, dimensional changes and attack by microorganisms and fungi. The changes in the moisture content of timber may influence such important parameters as mechanical properties and the total life time of the structural timber elements. A study has been conducted with the aim of assessing the efficiency of coating materials used for wood protection against water absorption. In this study, six different commercial coating products used for the treatment of spruce (Picea Abies L. Karst.) and pine (Pinus Sylvestris L.) samples were tested. The efficiency of different coating substances was assessed using two modified test methods according to the standards EN 382-2 (1994) and EN 927-5 (2006), determining the surface water absorption after immersion in water for 24 h and the dynamics of water absorption of the glued laminated timber for 696 h kept in water. As a result of the study, it has been ascertained that organic solvent-based commercial coating products are more efficient against short-term and long-term wood water absorption compared to oil-based coating materials.
Показать больше [+] Меньше [-]The influence of technological peculiarities on fermented sausages’ quality and sensory properties
2021
Gramatina, I., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Sauka, J., Ādažu desu darbnīca, SIA., Ādaži, Ādaži Parish, Ādaži Municipality (Latvia) | Semjonovs, A., Ādažu desu darbnīca, SIA., Ādaži, Ādaži Parish, Ādaži Municipality (Latvia) | Strode, S., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Straumite, E., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
Fermentation is one of the ancient technological processes used in food production which influences the shelf-life of meat and meat products, also significantly affects the sensory properties like aroma and flavour. The objective of the present study was to evaluate the elaborated technology for a new fermented sausage production on the product quality and sensory properties. Sausages were produced by the standard technology using glucono-delta-lactone or starter culture. The drying of samples differs from 3 to 4 weeks at the same conditions; samples were dried for 4 weeks which produced with the starter culture, and 3 weeks which produced with glucono-delta-lactone. The sausages were tested at the end of the production, analysing pH, water activity, moisture and salt content, as well as the presence of Listeria monocytogenes, colony forming units of Listeria monocytogenes and Enterobacteriaceae in the sausage samples were analysed. The sensory evaluation was organised after getting Listeria monocytogenes testing results. The moisture content, water activity and salt content significantly differed (p is less than 0.05) among samples, no differences were established in pH, taste and flavour liking. The presence of Listeria monocytogenes was not established in samples which indicates that the producer properly applies a hurdle technology in fermented sausage production. Sensory evaluation results showed higher scores for texture and appearance in fermented sausages with glucono-delta-lactone. The study results confirmed that fermented sausages with glucono-delta-lactone during 3 weeks of drying can achieve corresponding safety criteria and sensory properties which are set for semidry fermented sausages.
Показать больше [+] Меньше [-]Impact of high-pressure impregnation and fire protective coatings on the reaction to fire performance of birch plywood
2021
Rudzite, S., Latvijas Finieris, JSC, Riga (Latvia) | Buksans, E., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
Birch plywood has a wide range of applications for interior and exterior use. The demand for plywood with improved fire protection properties and good visual appearance is increasing year by year. The impregnation at high pressure of the whole plywood panels is one of the options to achieve it. The aim of this study was to develop good visual looking birch plywood product for interior design purposes as well evaluate different influencing factors to reaction to fire properties of fire-retardant treated birch plywood. This study consists of three parts. At the first stage, high pressure industrially impregnated plywood properties were studied by two influencing factors – distribution of fire retardant in plywood panel plane and sanding process influence on reaction to fire performance of product. At the second stage, seven different industrial finishing systems were selected for covering high-pressure impregnated birch plywood and their effect on fire reaction performance was studied. In addition, two surface coating systems were studied on standard birch plywood substrate. At the third stage, intumescent coating consumption effect on reaction to fire performance was studied. The reaction to fire performance of birch plywood was evaluated by performing a flammability test using the Single Burning Item test according to EN 13823:2010. It was found that high pressure impregnation of plywood cannot ensure even saturation of fire retardant throughout the sheet, which significantly affects the fire performance of product. The impact of different finishing materials to reaction to fire performance has been described by the results of this research.
Показать больше [+] Меньше [-]Purification of crude glycerol derived from hydrogenated cottonseed and its use in confectionary products
2024
Ruzibayev, Akbarali | Abdurakhimov, Ahror | Calvo-Gomez, Octavio | Akhmedova, Shahlo | Kurambayev, Sherzod
Glycerol is a versatile substance used in food, beverages, cosmetics, and technical applications. It can be derived from fats and oils through 4 different reactions, including: transesterification, directed hydrogenation, hydrolysis, and saponification. Glycerol derived from fat hydrolysis yields superior quality and quantity when compared to saponification. The resulting glycerol water is purified and concentrated through evaporation to yield crude glycerol with a concentration of 86–88%. Two distinct methods are recognized for further improving quality of glycerol: distillation, and the purification of glycerol water through the ion exchange process followed by evaporation. The goal of this research was to improve the purification process of glycerol, for obtaining premium-quality glycerol without the need for distillation, through the utilization of cations. Several combinations of activated carbon and clay were tested, and it was determined that a combination of 70:30 yielded the optimal results, considering the amount of glycerol and ash content. Technological parameters such as reaction durations, pH, and process temperatures were investigated, and it was discovered that the appropriate combination was a process duration of more than 40 minutes, a pH value of 2, and a temperature of 70 °C. Besides, it was also determined that the concentration and quality of glycerol derived from cottonseed oil can be enhanced through distillation or purification with cationite. Moreover, different concentrations of glycerol on the elaboration of gingerbread were tested, and the conclusion is that adding 5% of the resulting glycerol to the gingerbread recipe could ensure better preservation of its quality during its shelf life.
Показать больше [+] Меньше [-]Fatty acid composition of different breed goat milk
2023
Marcinkoniene, Liga | Ciprovica, Inga
The chemical composition of goat milk, especially fatty acid profile is recently renewed due to the role of monosaturated and polyunsaturated fatty acids in human nutrition. These nutrients are important to analyse in connection with the different breeds receiving the same breeding and feed. The aim of this study was to analyse goat milk fatty acid profile in relation to different breeds. Specimens for fatty acid analyses were collected from individual animals of breeds like Latvian Native (n=5), Saanen (n=5), and crossbreeds (n=5). Bulk milk samples (n=5) were also taken for milk quality testing and fatty acid range determination. Fat content was analysed according to ISO 1211:2011 and fatty acids were measured with the chromatographic method. Protein, lactose, casein and urea concentration was analysed according to ISO 13366-2:2007 and somatic cell count to ISO 9622/IDF141:2013.The highest fat concentration was determined in crossbreed milk samples (3.81 g 100 gE−1) and the lowest (2.96g 100 gE−1) in the Latvian Native breed goat milk samples. The highest butyric acid (0.12 g 100 gE−1) and caproic acid (0.12 g 100 gE−1) concentration was established in Saanen goat milk samples. Compared to other breeds, the milk of the Latvian Native breed goats is characterised by a higher capric acid (0.20 g 100 gE−1) concentration, while a higher concentration of total unsaturated and monounsaturated fatty acids was detected in the samples of crossbreed goat milk. The average fatty acid composition of bulk milk samples was 68% for saturated fatty acids, 23% for monosaturated fatty acids and 4.3% for polyunsaturated fatty acids. In analysed goat milk samples, fatty acids showed the characteristic fatty acid profile of goat milk.
Показать больше [+] Меньше [-]Sound absorption properties of the patented wood, lightweight stabilised blockboard
2023
Roziņš, Rihards | Brencis, Raitis | Spulle, Uldis | Spulle-Meiere, Ivanda
It is well known that wood tends to shrink and swell as the relative humidity of the air changes. There have been, and still are, attempts to make dimensionally stable wood panels such as Dendrolight®. The physical-mechanical, operational, including acoustic, properties of this material have been significantly improved compared to traditional wood-based panels. However, the production of this material requires very specific processing equipment and a large energy investment. The developers of this material in Latvia invented and patented wood, Lightweight Stabilised Blockboard (LSB). In order for this material to be used in the production of various products, it is necessary to clarify its characteristic, technological, as well as operational properties. The study gathers information about the sound absorption properties of various natural and wood materials, characteristics, and the sound absorption of the studied material at different sound frequencies. The reviewed sources of information indicate that nowadays there are still problems in sound conduction and absorption and isolation issues are being addressed in building acoustics. The production of samples and the determination of sound absorption were carried out using a developed methodology developed in accordance with regulatory requirements. The data obtained in the practical study were compared with the relevant indicators of the Dendrolight® and wood-based panels used for building structures and to determine their compliance with the requirements set forth in the standards ISO 10534-2 and ISO 11654. Research data show that LSB corresponds to E sound absorption class in some of the investigated frequencies.
Показать больше [+] Меньше [-]In vitro testing of lactic acid bacteria from commercial yoghurts
Lakstina, Jana | Ciprovica, Inga | Majore, Kristine
Yoghurt has been known as an excellent source for delivering viable lactic acid bacteria (LAB) in concentrations providing benefits to the human host and microbiome. Different gastrointestinal tract (GIT) simulators have been developed and are successfully used to determine the viability of LAB from fermented dairy products in vitro studies. Commercial yoghurts were tested for digestibility using the GIT IT system Labfors 5 (INFORS HT, Switzerland). The length for both the gastric phase and the small intestinal phase was 120 min each. Yoghurt LAB colony-forming units were analysed prior to the GIT simulation test, as well as after the simulation test. The survival rate of LAB was evaluated based on the differences in the viable LAB count at the beginning and at the end of the experiment. Tested yoghurts’ LAB were tolerated in the simulated gastric and small intestinal phases. Samples collected prior to and after the intestinal phase revealed that LAB had adapted and started to grow within 120 min. Our results showed the ability of LAB to recover in the intestinal phase which has been explained by the food matrix, which protects the bacteria from the elimination effect of intestinal secretions. In addition, differences in survival rates of LAB significantly influenced the overall LAB colony-forming units in the gastrointestial tract. The chemical composition of the product has an influence on the survival rate of LAB, and it should be studied more thoroughly. In vitro studies are quite different from the assay in vivo studies; however, this information provides significant data about the viability of LAB from regularly consumed products and helps to modulate the influence of LAB on human microbiota.
Показать больше [+] Меньше [-]