Three spectrophotometric methods were compared for the assessment of milk fat oxidation: the AOCS (American Oil Chemists' Society) 2-thiobarbituric acid (TBA) value direct method, the TBA method of Aristova, and the modified method for the estimation of total carbonyl compounds in oils of Endo et al. Two cow milk fat samples – a fresh fat, obtained from fresh milk, and a rancid fat, obtained from a rancid commercial butter by means of high-speed centrifugation (15.871 × g, 30 minutes at 40 deg C) – were analyzed several times in a 22-day period after sample preparation. A positive linear correlation between absorbance and storage time was established in all used methods. The method of Aristova is appropriate for exact determination of oxidation products. This method had rather good R2 value (0.85) of the fresh fat sample results; however, the coefficient of variation (45.78%) showed rather large deviations between parallel analyses. The methods of AOCS and Endo et al. can be used for the assessment of the dynamics of fat oxidation by reporting absorbance values from the assay directly. By these methods rather high R2 values (0.86, 0.93) of the fresh fat sample results were obtained; the coefficients of variation also were satisfactory (10.13%, 11.12%). The last two methods are cheaper and require smaller sample amounts (less than 0.2 g), while the method of AOCS is the most time-consuming method.

Cereal grains have long been thought to be less important sources of antioxidants than fruits and vegetables although they contain many antioxidants and are major dietary components worldwide. The aim of the current research was to study and compare an antioxidant activity (AOA) and total phenolic content (TPC) of different barley varieties and malt types as well as to evaluate possible interconnection between TPC and AOA of barley and malt samples. The research was carried out on four lines of hull-less barley ‘3528’; ’L-400’; ’3475’; ‘3537’ and one variety of flaky barley ‘Klass’ grains, which were cultivated in Latvia in 2010, and their corresponding malt. Commercial sorts of malt - Pilsener, Munich, Caramel and Dark were used in the research to compare with the malt produced in the laboratory scale. The antioxidant potential of barley and their products is analyzed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Total phenolic content of barley and malt samples was determined according to the Folin-Ciocalteu spectrophotometric methods. The values of DPPH radical scavenging activity for 5 barley samples ranged from 4.57 to 5.89 μmol TE gE-1 DW. The total amount of phenols ranged from 1.96 to 2.43 mg GAE gE-1 DW for unprocessed barley samples and from 2.5 to 3.4 mg GAE gE-1 DW for their corresponding malt. TPC of malt commercial sort ranged from 3.5 to 6.7 GAE gE-1 DW. The increase of TPC for commercial malts is strongly related with Maillard reaction products.

Thermal wood modification has been intensively studied in the recent decades because of the possibility to produce wood with improved biodurability and dimensional stability without use of harmful chemicals. Beside altered physical characteristics, wood colour is changed to lighter or darker brown as a result of thermal treatment. Growth of interest in thermal wood treatment has stimulated numerous researches concerned with discoloration of thermally modified wood which is subjected to light exposure. The objective of this study was to evaluate the colour stability of thermally modified hardwood during storage in the dark where wood discolouration is not photoinduced but rather a result of oxidative ageing. Three thermally modified hardwood species – aspen (Populus tremula L.), alder (Alnus incana Moench), birch (Betula pendula Roth.), where investigated. Wood discoloration was monitored by spectrophotometrical measurements of reflectance spectra and chromaticity parameter calculations using CIELAB colour system where L* is the lightness, and a* and b* are the chromatic coordinates. The colour stability of thermally modified wood as well as of untreated wood of the same species was examined by means of assessment of the colour parameter changes (ΔL*, Δa*, Δb*, ΔEab). All wood specimens under study discoloured during the experiment, but the colour change did not exceed two units that are common and accepted for wood products. Untreated and thermally modified wood showed different trends of discoloration during storage in the dark. The final colour changes that were fixed at the end of the experiment were greater for the thermally treated wood.

The main purpose of the present experiments was to investigate the effect of various hydrogen peroxide (H2O2) concentrations and for various lengths of treatment on the total carotenoid, β–carotene content, colour intensity and microbiological safety on the fresh shredded carrots. Shredded carrots were dipped in 0.5, 1.0 and 1.5% H2 O2 water solution for 30 ± 1s, 60 ± 1s and 90 ± 1s. Negative effect of H2 O2 on β–carotene content and colour parameters of analyzed shredded carrots samples was not detected. In carrots treated with H2 O2 (p = 0.008) for 60 – 90s the total content of carotenoids significantly decreased during treatment compared to untreated carrot samples. There was significant difference (p is less than 0.05) observed between treated and non–treated shredded carrot samples on the total bacteria count. It was possible to reduce significantly (p is less than 0.05) the content of yeasts and mould up to 99.99% by shredded carrots treatment with 1.5% hydrogen peroxide water solution for 30 ± 1s. In the non–processed carrots E.coli was detected; however, it was possible to destroy E.coli by treating carrots with 0.5% H2 O2 water solution for 30 ± 1s. Considering all experimentally obtained results, we have concluded that fresh shredded carrots could be treated in water with the addition of hydrogen peroxide 1.5% for 30 ± 1s to maintain quality.

Horseradish (Armoracia rusticana L.) is a perennial herb belonging to the Brassicaceae family and contains biologically active substances. The aim of the current research was to determine the most suitable extraction method and solvent for obtaining horseradish leaf extracts with high antiradical activity. For experiments fresh leaves of horseradish were extracted with seven different solvents: n-hexane, diethyl ether, 2-propanol, acetone, ethanol (95%), ethanolwater/acetic acid (80/20/1 v/v/v) and ethanol / water (80/20 by volume) using two extraction methods (conventional and Soxhlet). For all extracts, total phenolic, flavonoid content and DPPH˙, ABTS radical scavenging activity, and reducing power were determined using a spectrophotometric method. As the best solvent can be used ethanol. Total phenolic content and total flavonoid content was higher in Soxhlet extracts. Comparing to other plants, the proportion of flavonoids in the amount of total phenolics is average, and it increases by increasing the polarity of used solvent. It can be concluded that by using Soxhlet extraction method it is possible to obtain extracts that are effective antioxidants. A very strong and a strong correlation has been identified between levels of phenolic compounds and antioxidant capacities of the extracts.

Surface water runoff, formed in the company areas due to changing wastewater discharge and pollution fluctuations can be treated in retention ponds. Pollutants, released into the ponds, mineralize during complex natural biochemical processes in the aquatic environment. The paper presents the long-term observation data (2004 – 2016 m.) on the purification of surface wastewater, formed in the company’s production territory, in retention ponds. The aim of this work is to identify surface wastewater purification efficiency in retention ponds. Wastewater samples were taken before and after biological treatment. The samples were investigated in the Chemical Analysis Laboratory of the Water Research Institute of Lithuania University of Agriculture. Biochemical oxygen demand (BOD7 ) was determined with titrometric method, suspended solids (SS) – with gravimetric method, having filtered the substance through a mid-thickness filter. Concentrations of oil pollutants were determined with the help of a spectrophotometric device of infrared rays IKAN-1 in the Analytical Department of Agrochemical Study Center of Lithuanian Agricultural Institute. Although the suspended solids, BOD7, and oil hydrocarbon concentrations, released into the natural environment, were below the MAC when they are collected from the company’s production areas, they are often contaminated; therefore, it is necessary to treat them. The purification efficiency of researched materials was satisfactory and reached 61, 64 and 91%.

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.

Legumes are becoming more popular in food and feed consumption. They are promoted by EU policy related to healthy lifestyle and environmental policy. Legumes can be grown in crop rotation as monocrop or in different kind of intercropping systems. It is a well-known fact that legumes play an important role in fixation of the atmospheric N, whereas their influence on other biological and chemical aspects of the soil ecosystem is only explored partially. The experimental trial was established at the Pūre Horticultural Research Centre with the aim of studying the influence of legumes on the soil properties in the intercrop with strawberries (Fragaria × ananassa Duch.). Different genotypes were included in the trial as intercrops: two local broad beans (Vicia faba var. major L.) genotypes, two pea (Pisum sativum L.) cultivars and clover (Trifolium hybridum L.). Two control treatments were included in the trial: with and without nitrogen fertilizer usage. Strawberries were planted in May of 2014 and maintained in the field for three years. Results showed that there were significant differences between treatments in soil respiration rate (SRR) and SRR dynamic throughout the experiment time. Dehydrogenase activity had similar results, though no significant differences between treatments were observed in the third year. No significant difference between treatments was found in the soil organic matter. Obtained data shows that legumes have a significant influence on the soil biological properties but not on biochemical properties. Further research needs to be carried out to determine legume influence on soil environment in more detail.

Vegetable processing in food industry results in significant number of by-products – peel, mark, bark, seeds still rich in bioactive compounds. The objective of this study was to investigate the stability of total phenolic content (TPC) and antioxidant activity after high temperature short time (HTST) extrusion cooking of a rye and oat- based matrix with addition of apple, carrot and pumpkin by-product flour (BPF) in various amounts (5%, 10%, 15% and 20%). Extrusion was performed with co-rotating twin-screw extruder (compression ratio 8:1) at Ltd MILZU. The main drive of extruder was provided with a 7.5 HP motor (400 V, 3 HP, 50 cycles). Temperatures for extrusion zones were 125 °C /135 °C /145 °C. TPC was determined using the Folin Ciocalteu method. Antioxidant activity was evaluated by free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant scavenging activity. TPC in cereal-based crispbread was 62.03 ± 0.15 mg GAE gE-1 DW before extrusion and 37.73 ± 1.96 mg GAE gE-1 DW after extrusion. Addition 20% of apple BPF increased TPC in crispbread to 193.92 ± 1.37, carrot BPF 171.36 ± 6.97 and pumpkin BPF to 195.09 ± 4.68 mg GAE gE-1 DW after extrusion. Antioxidant activity of control (20% oats, 80% rye flour blends) sample was 0.516 ± 0.192 mg TE gE-1 DW but in samples with addition of 20% by-products, it was significantly higher reaching 0.926 ± 0.05 TE gE-1 DW in samples with pumpkin by-products after extrusion.

Honey is a naturally supersaturated sugar solution, which tends to crystallize. The crystallization of honey can lead to unwanted fermentation that can have a negative impact to honey quality. The production of honey powder could be an alternative method to prevent honey from fermentation. Honey powder could be used as alternative substitute to liquid honey that would allow to use this product more widely in the food industry. α-amylase activity is one of the most important parameters to evaluate the quality of honey. The aim of this study was to investigate the effect of freeze-drying and spray-drying on honey α-amylase activity. Detection of α-amylase activity was carried out by spectrophotometric method. High-performance liquid chromatography was used to determine the content of hydroxymethylfurfural in the powders. The obtained results showed that both drying methods had a negative impact to the enzyme activity in the samples. The lowest activity of α-amylase (8.3 DN) was measured in the spray-dried honey powder. Concentration of hydroxymethylfurfural (HMF) in the powders did not exceed required concentration 40 mg kgE−1.