Products of organic origin used in agriculture to reduce the application of artificial pesticides and fertilizers are investigated world-wide now. Composting organic fertilizers, plant residue and household waste, results in new products of organic origin. In several countries (USA, Russia, Belorussia, and some others), the role of earthworms in organic waste processing and the possible further use of this processed product have been investigated. In Latvia, similar investigations are few but they are needed. A goal of our investigation was to investigate the impact of extracts made from the products of organic origin on potato (Solanum tuberosum) tuber yield in biological crop production system. A field experiment was established at the State Stende Cereals Breeding Institute in 2011, using an early-maturing potato variety ‘Borodjanskij Rozovij’ suitable for growing both in conventional and organic production systems. Tubers or plants were treated with peat elixir and earthworm bio-humus extract obtained at different temperatures: +45 °C and +95 °C, and their mixtures. In total, 18 treatments and untreated control variant were included in the experiment. Tubers were treated just prior to planting, but potato plants were treated three times in season. In the first production year, the obtained potato tuber yield ranged 26.16-45.38 t haE-1 in treated plots, and 35.27 t haE-1 in untreated control plot. Data were subjected to analysis of variance. In 2011, tuber yield was significantly dependent on organic extracts applied, which increased the yield significantly (p is lee than 0.05) in four treatments, but in the rest of them significantly decreased if compared to control.

Oregano (Origanum vulgare L.) is one of the most popular spice and medicinal plants of untraditional horticulture in Latvia. Wild populations of this plant are too few. That is why it is necessary to cultivate oregano for keeping the biodiversity of Latvian nature. It is important to use local oregano genetic resources in agrocenosis as well as to get as rich and qualitative yield as possible. The aim of this research was to explore the parameters of oregano inflorescence in Latvia and to recommend the most productive clones for cultivation. In summer 2011, a total of 45 oregano clones from an ex situ collection of spice and medicinal plants of the Laboratory of Cultivated Plants and Apilogy (Jelgava, Strazdu Street 1) were analysed. Such inflorescence parameters as length and width were explored. The average length of inflorescence of all clones was 17.99 cm, and the average width was 5.74 cm. The results showed that the clone No 26 had the largest width of inflorescence (9.6 cm), but the clone No. 2 had the largest length of inflorescence (31.1 cm). Using oregano Draft Descriptor List, the inflorescence was characterized as short, medium or long. The variability between clones was significant (p is less than 0.05), but between samples of each clone - non-significant (p is greater than 0.05). It is recommended to grow oregano clones No. 2, 5 and 26 in agrocenosis as the most productive.

Blueberry cultivation is becoming more and more popular in Latvia, and several commercial plantations have been established recently. Highbush blueberries (Vaccinium corymbosum L.) are perennial and can grow without replanting for 50 years; therefore a choice of soil and its preparation have a great role. This article summarizes results of research carried out in commercial blueberry plantation established in 2004 on loamy Haplic Cambisol. Soil properties, especially reaction and organic matter content, initially were not suitable for blueberry cultivation, therefore deep tillage and application of soil conditioner (acid sphagnum peat) were done before planting and similar peat mulch was applied every second year. Berry yield of 4 blueberry cultivars, soil properties and the nitrogen, phosphorous and potassium content in growing plant leaves were determined. The obtained results showed that sphagnum peat is an effective material for lowering of soil pH in plant root layer (0 – 40 cm). Data about plant nutrient content in topsoil and subsoil as well as in growing plant leaves will help to develop criteria for soil fertility assessment and diagnosis of plant nutrition.

The American cranberry (Vaccinium macrocarpon Ait.) is a perspective and marketable crop both in Latvia and foreign markets, but berries are affected by rot in storage. The aim of the study was to detect the incidence level of cranberry fruit rot at the beginning of storage period in different places in Latvia. In 2007 - 2011, two hundred sound berries (out of 1000) were randomly collected by hand along a diagonal from five different cranberry plantations from locations all over Latvia. Berries were kept in plastic bags for a month and refrigerated at +7 °C. At the end of November, berries were sorted and rotten berries were separated from the sound ones. Over the period of 2007 - 2011, the incidence of storage rot reached 12 - 15% at the end of November, with an upwards trend observed every year, but the hot and rainy summer of 2010 significantly reduced the quality of fruit in storage, peaking on the average 33% of decayed berries. The incidence of fruit rot varied among the inspected cranberry plantations, but a tendency was observed that older plantations produced more rotting fruit and incidence of the disease was 12 - 50% after a month’s storage in the oldest plantation. The application of fungicides during the vegetation season did not affect development of post-harvest rot. Storage rot was a problem in the cranberry samples from all inspected plantations in Latvia, and in future the incidence of fruit rot is expected to increase.

This paper discusses some aspects of introducing a new agricultural crop in Latvia – truffles Tuber spp. Truffles are mycorrhiza–forming mushrooms with edible fruit bodies developing in the upper layer of soil. In Latvia, there is a growing interest among farmers to start cultivate truffles. From several cultivated truffle species, the Burgundy truffle Tuber aestivum syn. T. uncinatum is the most suitable to cultivate in Latvia. There are both autochthonous and introduced tree species in Latvia, which are suitable for the Burgundy truffle cultivation and it is suggested to use Quercus robur, Corylus avellana, Tilia cordata and Fagus sylvatica. In order to find the regions in Latvia with the highest potential for successful Burgundy truffle cultivation, climate and soil characteristics had been co-analysed. By superimposing soil and climate maps of Latvia, the most suitable regions for truffle cultivation are situated in the central and southern part of the country. Considering the variability in soil composition even within regions in Latvia, it is thereafter also of great importance to investigate site-specific soil characteristics in order to find the most favourable grounds for truffle cultivation. Other truffle species which might be suitable for cultivation in the future are also discussed, as well as some general recommendations in establishing truffle orchards.

Advances in milk production and the expansion of dairy herds have increased the need for improved manure management and whole farm nutrient balance. It is well known in dairy management that the balanced feeding and holding technology is an important level by which milk production and milk composition can be modified. The objective of this study was to evaluate urea content and urea yield in different farms with different holding technologies. Four farms represent three cow breeds (Holstein Black and White, Latvian Brown, and cross breed XP). Individual cow milk samples (n=2740) were collected monthly from September 2009 to November 2010. Milk samples were analyzed for total protein, casein, fat, lactose, and urea content with instrumental infrared spectroscopy method. The average milk yield per cows in farms was significantly different (from 27.9 to 17.0 kg per control day). The urea content in cow milk was between 20.3 to 46.6 mg dLE-1. The average urea content in farms A, B and D was up to standard (from 15.0 to 30.0 mg dLE-1). In the farm C, average urea content ranged between 17.4 and 79.9 mg dLE-1, which indicated problems in feeding or management in the farm. It was established that milk urea content and yield significantly (p is less than 0.05) varied in farms with different dairy cow holding and feeding technologies. Urea content can be used to evaluate feed protein utilization in farms and predict environmental pollution.

Apples are the most popular and common fruits in Latvia. Storage technology is crucial to preserve fruit quality as long as possible. Choosing the appropriate gas content of the storage environment can prolong storage life two to three times for apples. The aim of the research was to compare six different type of apple grown in Latvia, which was stored in diverse conditions. All experiments were performed at Latvia State Institute of Fruit-Growing through 2011 – 2012. For fruits before storage, 1-methylcyclopropene (1-MCP), which blocks the emission of ethylene, was used. Apples were stored in a cooler and in ULO type plastic bags in a modified environment with two different gas contents. The temperature of the environment was +2 ±1 °C with 90% relative humidity. Changes in physicochemical (soluble solids, total acids and flesh density) indexes were examined before and during the storage. The results showed 1-MCP has a positive effect on quality preservation of fruit. Fruits stored in ULO type plastic bags (gas content: 1.5% O2 and 2.5% CO2) had the best results in preservation of physico-chemical indexes. Examination of results revealed that physico-chemical indexes changed the most in samples stored in the cooler.

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.

Cereal and whole grain products are an important source of dietary fiber in the human diet. Since the milling process highly influences the proportions of the different cell types in the bran, it is expected that brans originating from different genetic/agricultural backgrounds and produced by different processes have different chemical composition. Wheat (Triticum aestivum) bran has not been studied in Latvia, therefore the aim of the present study was to analyze physical – chemical characteristics of wheat bran from Latvia’s industrial mills. Four bran samples were collected from two industrial mills: Stock Company ‘Dobeles dzirnavnieks’ and SC ‘Rigas dzirnavnieks’. All experiments were performed at the Food Technology of Latvia University of Agriculture in May 2011-February 2012. The particle size distribution of the bran samples was determined by sieving. The content of titratable acidity (TA) was detected by titration with 0.1 M NaOH till pH 8.5 was stable for 1 minute. Wheat bran colour was analysed by Hunter Lab colour measurement instrument using ColorTec colorimeter PCM/PSM in CIE L * a * b* system. Moisture content was analyzed using standard ICC 110/1 method by sample drying for 2 h at 150 °C. Results showed that there were significant differences between varieties (p0.05) for titratable acidity and for particle size, but no significant differences (p0.05) were found between the varieties in moisture, pH and colour. TA varied from 6.40±0.71 to 12.05±0.21°, moisture content- from 10.01±0.51% to 11.61±0.47%, pH–from 6.31±0.61 to 6.80±0.05, but colour of bran between the samples did not significantly differ.

The survival of inoculated in a cold-smoked sausages Listeria monocytogenes wild strains was studied. The sausages were prepared with and without starter cultures. The survival limits of L. monocytogenes and lactic acid bacteria (LAB) were determined as colony forming units per gram (cfu gE-1) depending on water activity (aw) and pH on 0, 1st, 3rd, 5th, 7th, 14th and 21st days of maturation. The decreasing water activity conditioned by moisture (weight) loss during ripening and pH decrease ensured negative polynomial growth rate of inoculated L. monocytogenes - 0.27 lg (cfu gE-1) each day of ripening time, and - 0.65 lg (cfu gE-1) on the first 7 days of maturation. A significant Pearson’s correlation (p is less than 0.01) was established between decreased values of L. monocytogenes count, aw, salt concentration and LAB growth in sausages during the ripening period of 21 days. The main parameters, maintained negative exponential growth rate of L. monocytogenes in cold smoked sausages, are aw value decrease and LAB (starter culture), which stopped L. monocytogenes growth at the beginning of cold-smoked sausage maturation. If fermentation process went technically and hygienically correctly, the fermented (cold-smoked) sausages could be one of the safest meat products, because in real practice a low level contamination has been seen. The remaining count of L. monocytogenes in cold-smoked sausage depends on the possible initial contamination level and could exceed the European Union regulation value 2.0 lg (cfu gE-1) for ready-to-eat products when contamination at first is more than lg 5.0.