The growing economy with following industrialization and urbanization has led to environmental contamination with trace elements worldwide. In urban environment, the large inputs of anthropogenic contaminants in atmosphere are arising from mobile and stationary sources. The snow sample analysis is one of methods to monitor air contamination with heavy metals in urban areas. The aim of this research is to analyse heavy metal contamination and distribution in urban environment of Jelgava city. The samples were collected twice in January and February. Snow samples were collected in 20 urban area sampling plots and one natural area sampling plot with three repetitions taken from 1.0 to 1.5 kg of snow. The concentration of trace elements was estimated in 126 melted and filtrated snow water using inductively coupled plasma spectrometer (ICP-OES). The average heavy metals and nutrients concentrations were calculated for each sample. The concentrations data of trace elements were analysed using agglomerative hierarchical clustering method. The results show differences between results in January and February. The differences are related to anthropogenic impact intensity differences during the exposition periods of snow. The clustering results of snow samples taken in January show three clusters, but snow samples taken in February show four clusters.

As European Union member states – Latvia and Lithuania have changed their national height systems from Baltic Normal Height System 1977 to European Vertical Reference System realizations. Performing practical Global Navigation Satellite System (GNSS) measurements and obtained data mathematical processing, there is a possibility to calculate point height difference between GNSS data and data of 1st order levelling networks. The aim of the research is to gain insight for methodology development of geodetic point height testing using GNSS measurements. To achieve the goal following tasks are set: 1) perform GNSS measurements of first order levelling network in Latvia and Lithuania; 2) do data processing to get point ellipsoidal height and compare with the point normal height; 3) detect technically feasible accuracy of geoid model for precise height measurements with GNSS method within research area. Performing GNSS measurements at the same time in the territory of Latvia and Lithuania, the experience of mutual cross-border cooperation was accumulated. The results were adjusted with academic software package Bernese and were obtained point ellipsoidal and normal heights. The height measurement accuracy using GNSS method depends on geoid model accuracy and more precise results can be obtained increasing used geoid model accuracy to 1.5 to 2 cm.

Enteral feeding also known as enteral nutrition is nutrient delivery into the stomach. Products for enteral nutrition are a specific group of products designed to provide nutrients to the human body in case of various diseases and after surgery, when the daily intake of the product is affected. Today market offers special dietetic products, which are supplemented with synthetic vitamins and minerals, which bioavailability in the body is lower than that of natural organic complexes. Therefore it is important to develop special dietetic products from natural raw materials. The aim of this study was to evaluate the effect of vacuum cooking on the content of bioactive compounds, soluble solids, pH and shelf life of enteral food made from fresh and semi-finished (heated) fruit and vegetable juices. For this research enteral food was made using fresh or semi-finished fruit and vegetable juices. Products were vacuum cooked in 0.02 MPa pressure, with boiling point 67 °C, and 0.06 MPa pressure at 79 °C, withstander for 15 min. All samples were stored at room temperature and tested for their content of vitamin C, total carotenoids, anthocyanins, total phenols and antioxidant activity and microbiological safety, as control untreated enteral food samples were used. The obtained data showed that samples made from semi-finished juices have higher contents of vitamin C and total carotenoids and anthocyanins than samples prepared from fresh juices, but this wasn’t observed with content of total phenols and antiradical scavenging activity (DPPH), where the type of ingredients used for sample preparation had no significant effect.

β-galactosidase (EC 3.2.1.23) is one of the widely used enzymes for lactose-free milk production and whey permeate treatment. Enzymes can be obtained from microorganisms, plants and animals. Nowadays, microorganisms are becoming an important source for production of commercially available enzymes, which are of great interest and offer several advantages such as easy handling and high production yield. The aim of this review was to summarize findings of research articles on the application of commercially available β-galactosidase preparates in dairy industry, to analyse and compare the most suitable β-galactosidase commercial preparates for lactose hydrolysis. The results showed that the main factor to choose an appropriate β-galactosidase for lactose hydrolysis was reaction condition. Enzymes from microorganisms contain a wide range of optimal pH from 4.0 (Penicillium simplicissimum and Aspergillus niger) to 8.5 (Bacillus subtilis). The greatest commercial potential has enzymes obtained from fungi (Aspergillus oryzae and Aspergillus niger) and yeasts (Kluyveromyces lactis and Kluyveromyces fragilis). Fungal origin enzymes are more suitable for the hydrolysis of lactose in acid whey due to its acidic pH but yeasts origin enzymes for milk and sweet whey. In the study, commercial preparates from different suppliers with the purpose to analyse their lactose hydrolysis potential and give more detailed characteristics of each preparate advantages and drawbacks were also summarized.

Raw milk cheeses are known to have more intense and strong flavour and different texture due to natural microbiota and enzymes. Nevertheless, there are concerns about safety of these products. For microbial inactivation heat treatment of milk is used, but it can adversely affect the flavour, taste and texture of the product. Therefore, applying non-thermal technology such as high pressure processing is attracting alternative. The aim of this study was to examine the effects of high pressure treatment of cow`s milk at a wide range of pressures (400–600 MPa) on milk rennet coagulation time, curd firmness and curd yield. Processed milk samples were subjected to enzymatic coagulation using commercial rennet to determine rennet coagulation time, yield of coagulum and curd firmness. High pressure processing insignificantly influences coagulation properties of whole milk. However, the magnitude of changes depended on applied pressure. Rennet coagulation time and curd yield were significantly different (p is less than 0.05) among the pressure treated milk samples. The higher firmness of the curd form pressurized milk than that of raw or pasteurized milk, evaluated positively. The main effects of high pressure treatment in milk appeared to involve dissociation of casein micelles from the colloidal to the soluble phase. This study suggests that high pressure treatments of milk at 500 MPa or 550 MPa for 15 min may be beneficial for improving the coagulation properties of milk. These positive effects indicated that high pressure processing may have potential for new cheese varieties development.

Fresh meat is a highly perishable product due to its biological composition as it serves as an ideal environment for the growth and propagation of microorganisms and common food-borne pathogens. High pressure processing (HPP) is a cold pasteurization treatment to extend shelf-life while preserving the sensory and nutritional characteristics of the product. The aim of this research was to evaluate the effects of HPP on the fresh porcine Musculus longissimus lumborum microbial load and related physical properties (pH, water activity aw, and moisture content). Vacuum packed meat samples were treated at 50, 100, 200, 300, 400, and 500 MPa for 1, 5, and 15 min in a high-pressure processor ISO-Lab S-FL-100-250-09-W (Stansted Fluid Power Ltd., UK). Pressure treatment above 300 MPa resulted in a significant (p is less than 0.05) decrease of total plate count. However, the studied pressurizing time had no significant effect on microbial lethality at the same pressure applied. Other important parameters such as water activity, moisture, and pH were determined as they directly affect microorganism growth and resistance to pressure. A slight increase in pork pH was observed with increased pressure. No significant changes in water activity and moisture content were observed as a result of high pressure treatment. For future researches it would be important to evaluate the dynamics of microbial growth during storing as part of cells after pressure treatment are injured and not eliminated immediately; therefore, microbial count may further decrease during cold storage.

Lake sediments have a broad range of elementary and organic substance content. Bottom sediments collect decaying organic debris of aquatic plants and animals mixed by water drift with mineral constituents - deposited in the bottom of the lake in anoxic conditions. Lake Alūksne is situated in Northeast Latvia and is of glacial origin. Its water and bottom sediments chemical content depends on formation conditions – influenced also by anthropogenic activities. In order to determine environmental quality for restoration purposes and sediment recovery, geochemical research is needed. This paper aims to study bottom sediments – texture, ash part, organic compounds and metals to pinpoint necessary steps that are crucial for distinguishing environmental quality of the lake through geochemistry research. Bottom sediments contain sapropel with large admixture of organic compounds and microelements that may significantly influence biota and human health if concentration exceeds natural background levels. When bottom sediments are recovered, it may improve oxygene conditions in the lake, extracted sapropel can be used as a fertilizer, therapeutic agents, supplements for farm foods. Generally, sapropel is improving the structure of agricultural soils, increasing the cation exchange capacity and serving as binding material for complexes formation; thus diminishing ecotoxicological exposure threats of heavy metals, increasing yields and albumen and protein quantity in plants cultivation products. As these sediments can be used for soil fertilizing and crop production improvement in agriculture, mechanisms of ecotoxicological impact to various soil types and agricultural plant ecology should be researched.

Eutrophication caused by water pollution with nutrients (nitrogen (N) and phosphorus (P)) is one of the main environmental problems nowadays. Poor water quality might be caused by many natural and anthropogenic factors. The most common anthropogenic factors are water pollution caused by intensive agriculture (e. g. intensive fertilizer use, high density of livestock) and discharges from municipal waste water treatment plants (WWTP). In this study, nutrient load from WWTP to the River Berze basin in time period from the year 2005 to the year 2015 was described. In total, 23 WWTPs of the study area were analysed using descriptive statistics to calculate average values of nutrient amount and concentrations discharged to River Berze basin. From 2005 to 2015 average N and P load from WWTP to the River Berze basin have been reduced, but concentration of N and P in treated wastewater (WW) have increased. The largest WWTP of the study area – Krigeri (WWTP of city Dobele) is subject to the regulations of treated WW quality set by Republic of Latvia Cabinet Regulation No. 34. The WWTP Krigeri meets the regulations, but overall situation in the study area suggests that strict control of smaller WWTP should be made.

Our previous research was focussed on evaluating spaces in the Soviet period housing estates in Riga according to theoretical model of spatial measurements. This model was based on assumption established ex situ that liking and perception of urban space is closely related to buildings. Namely, to the way walls of the buildings shape a setting in terms of its height, width, length. This current paper sets the goal to analyse the impact of landscape elements such as trees, benches, elevations of earth surface, playgrounds on the perception and preference of open spaces in situ. This is done to verify the hypothesis that landscape elements as well as the method of research play a role in our knowledge on how urban spaces are regarded. Semi-structured interviews in walk-along modus are used to talk to inhabitants about the ways they see and like yards and streets in three residential areas: ‘Agenskalna priedes’, ‘Kengarags’, ‘Zolitude’. The interview materials are analysed discursively. The extracted information is compared to the data previously acquired by using the model of spatial measurements. The results of interviews show that trees are the landscape elements that have the largest impact on how residents perceive the size of a space and how they like a setting. There are also other elements such as benches, playgrounds, elevations that play a role. The interview material displays deviations in preference and perception of the size of space compared to the model of spatial measurements. Yet these deviations can be adapted to the model.

Human milk provides infant with the required nutrients for growth and development. The aim of preliminary study was to determine macro- and micronutrients content in mature human milk among lactating women residing in Latvia and dietary habits affecting it. The study was carried out from November 2016 to February 2017. In total, 24 pooled diurnal milk samples were collected from mothers whose infants had reached the age of at least two months. Personal information of each participant was recorded, including mother’s age, weight and height parameters, sex and age of an infant, parity, breastfeeding pattern, milk expression method used for sampling. Eating habits were obtained using Monthly Food Frequency Questionnaire. Analysed elements were determined using inductively coupled plasma mass spectrometry (ICP‑MS Agilent 7700x, Japan). Concentrations ranged from 227.52 to 398.34 mg LE-1 for calcium, 58.56 – 256.38 mg LE-1 for sodium, 445.33 – 736.71 mg LE-1 for potassium, 25.73 – 49.52 mg LE-1 for magnesium, till 3.17 mg LE-1 for iron, 0.28 – 2.77 mg LE-1 for zinc, 0.06 – 0.43 mg LE-1 for copper, 2.00 – 44.00 µg LE-1 for manganese, 1.00 –10.00 µg LE-1 for chrome which is comparable to data obtained from other studies although chrome and manganese concentration was even higher than observed in literature. Cobalt and selenium content was below detection limit. Zinc content in human milk negatively correlated with baby’s age (p is less than 0.05). The content of majority of essential minerals in human milk was affected by mother’s dietary habits; however, more samples need to be analysed for representative conclusions.