The objective of the study was to investigate the microbiological content of cow (Bos primigenius) milk in Latvian organic farms according to season and herd size with a purpose to detect their impact on the distribution of mastitis causing pathogens in milk. Samples were collected in 14 organic dairy farms of Latvia, 4 times through 2012: in winter, autumn, spring and summer period. Raw milk samples (n=564) obtained from cow composite milk were studied. The samples were divided into three groups in accordance with the number of cows in the cow-shed: A (3-30), B (31-60) and C (61-124). The total colony count (TTC) and the isolation of mastitis causing bacteria were analysed using standard methods. Bacterial growth occurred in 90.4% of samples. Isolated microorganisms belonged to 35 species, and the following bacteria were the most prevalent agent, including Coagulase negative staphylococci in 29.4%, Staphylococcus aureus in 24.1%, Kocuria kristinae in 12.9%, and Enterobacteriaceae spp. in 10.3% out of 564 milk samples. Depending on the season, the average number of TCC was the lowest in summer (4.66 ± 4.01 log10 CFU mLE-1), moderately higher in spring and winter (4.72 ± 4.18 and 4.82 ± 3.54 log10 CFU mLE-1, respectively), but significantly higher in autumn (5.43 ± 4.80 log10 CFU mL-E1). Coliforms were not isolated from group A herds instead of B (3.1%) and C (4.6%). Occurrence of Staphylococcus aureus was noticeably higher in B (19.1%) and C (20.8%) than in A (12.6%) herds. Most of group A herds met the milk quality requirements, while group C herds produced more contaminated milk.

Kvass is a non-alcoholic beverage produced by fermenting kvass mash with yeast; alcohol content in kvass must be less than 1.2% alcohol by volume. Microbiological safety of kvass is an important issue because European Regulation No 2073/2005 on microbiological criteria for foodstuffs does not provide microbiological criteria for kvass production. Microbiological safety of kvass depends on raw materials, personal hygiene, environment, kvass blending and filtration. Experiments were carried out at the Latvia University of Agriculture Department of Food Technology from November 2013 to January 2014. The aim of this work was to assess the microbiological environment changes during kvass production process and shelf-life. Understanding the development of dynamic of microbiological environment provides a better management for kvass production processes. Samples of bread kvass were analysed during production (12 and 13 h) and storage (36, 60, 84, 132, 136 h) at 3 ± 1 °C to determine kvass quality. Yeasts (LVS EN ISO 21527 - 2: 2008), lactic acid bacteria (ISO 9332:2003) and total plate count (LVS EN ISO 4833:2003) were determined in kvass samples. Microorganisms in kvass were identified using API identification system; the dominating microflora in kvass was Saccharomyces cerevisiae and Leuconostoc mesentericus. Changes of total plate count during fermentation and maturation were not significant (p is greater than 0.05).

The present study was undertaken to estimate enzymatically hydrolysed and non–hydrolysed wheat (Triticum aestivum) and rye (Secale cereale) bran microflora. Enzymatic hydrolysis was accomplished by α – amylase from Bacillus amyloliquefaciens and by Viscozyme L which contain a wide range of enzymes responsible for the breakdown of carbohydrates into simple sugars. Wheat and rye bran samples were collected from native mills, namely Stock Company (SC) ‘Rigas dzirnavnieks’ wheat bran with large particle size (WLSR), SC ‘Jelgavas dzirnavas’ rye bran with small particle size (RSSJ), SC ‘Dobeles dzirnavnieks’ wheat bran with small particle size (WSSD) and wheat bran with large particle size (WLSD). Gained results indicate that before enzymatic hydrolysis all of the bran samples showed similar microbiological contamination with total plate count (TPC), yeasts and lactic acid bacteria. Enzymatic hydrolysis of bran gives the possibility to partially eliminate the microbiological contamination with TPC, yeasts and lactic acid bacteria. The amount of microorganisms after enzymatic hydrolysis (before storage) were decreased and ranged from 5.26 ± 0.04 to 5.45 ± 0.01 log CFU gE-1, from 4.81 ± 0.01 to 5.60 ± 0.05 log CFU gE-1, and from 4.09 ± 0.01 to 5.10 ± 0.05 log CFU gE-1, respectively. After eight weeks of storage (temperature – 20 ± 1 °C, relative humidity – 40 ± 1%) enumeration of microorganisms showed significant decrease of colony–forming units in all bran samples. The amount of TPC, yeasts and lactic acid bacteria in the control bran samples fluctuated in a range from 4.84 ± 0.04 to 5.49 ± 0.05 log CFU gE-1, from 4.86 ± 0.03 to 5.25 ± 0.03 log CFU g-1, 3.53 ± 0.03 to 4.21 ± 0.02 log CFU gE-1 respectively.

In Latvia, Picea abies and Pinus sylvestris as the commercially most valuable species make more than half of all woodlands. It has been found that about 23% of spruce stands are infected by root rot, caused predominantly by fungal pathogen Heterobasidion annosum s.l. To restrict the spread of root rot in coniferous forests of Latvia, the Joint Stock Company ''Latvijas valsts meži'' collaborated with Latvian State Forest Research Institute ''Silava'' in 2006 and launched a project for testing the Rotstop biological preparation, containing a suspension of Phlebiopsis gigantea spores. This project had a general task to accomplish Rotstop using technology approbation in Latvia and develop control system. Starting with the year 2008, preparation was used for stump treatment during thinning operations. When analysing the field data, a conclusion made in other studies was confirmed - P. gigantea colonizes pinewood more intensively even in case of improper stump treatment. It implies that the quality of stump treatment is decisive when using Rotstop for rot control in spruce stands.

The objective of the present study was to investigate the microbiological content of cows’ milk in Latvia’s organic farms with a purpose to detect potential microbiological threats in milk. Samples were collected in December 2011 at 12 biological dairy farms of Latvia. Raw milk samples (N=155) obtained from cow composite milk were studied. The total mesophilic aerobic and facultative anaerobic microorganisms (MAFAM), the presence of coliforms and coagulase-positive staphylococci, count of yeasts and moulds were analysed using standard methods. Of the sampled cows 50% had a low somatic cell count (SCC) (LESS THAN 200,000 cells mLE-1), 23% - high, but 27% had a very high SCC (greater than 500,000 cells mLE-1). The mean value of MAFAM in the samples with low, high and very high SCC was 4.7, 5.0 and 5.0 log10 colony forming units (cfu) mLE-1, respectively. The yeasts were present in 57% of milk samples with the mean concentration of 3.1 log10 cfu mLE-1. Moulds were found in 27% of all milk samples; their mean concentration was 4.4 log10 cfu mLE-1. Identified mould strains belonged to genera Absidia, Aspergillus, Geotrichum, Mucor and Penicillium. In cases of subclinical mastitis and latent mammary infection the most distributed mastitis pathogens were Staphylococcus aureus, Micrococcus kristinae, Bacillus cereus and coagulase negative staphylococci.

Antibiotic resistance of Staphylococcus is increasing worldwide. New antibiotics are used in big amounts in the meat production more and more. As a zoonosis, Staphylococcus aureus (S. aureus) is found in various species of animals and people, especially in those, who are working on commercial swine farms and slaughterhouses. The aim of the study was to find out the occurrence of S. aureus in different age groups of pigs on commercial swine farms in Latvia. Microbiological samples (n=702) including nasal, rectal, milk and air samples were collected during October 2013 from three closed farms of different sizes and several age groups of pigs and investigated with microbiological standard methods. S. aureus was found in all swine farms. The occurrence of S. aureus in Latvian pig farms was 41% and the highest occurrence of S. aureus was among 3-3.5 month old piglets. S. aureus was 1.8 times more frequently found in nasal than in rectal samples, and only in 28.38% of pigs S. aureus was in both - nasal and rectal samples. S. aureus was found also in sow milk in 13% of samples and in 3 samples of air (n=23).

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.

Malt is a natural food product produced by germinating cereal grains. Safety of cereal grains and cereal products is a very important area. Experiments were carried out at the Faculty of Food Technology of the Latvia University of Agriculture. The research object was rye malt. The purpose of the research was to investigate and compare the influence of copper and selenium on microbiological indicators of rye malt. Rye grains of 96% viability were soaked and germinated at temperature +6 ± 2 °C for 4 days, using copper(II) sulphate pentahydrate CuS04*5H2 O solutions (Cu concentration 10 mg LE-1, 50 mg LE-1, 100 mg LE-1) and for 3 days using sodium selenate Na2 SeO4 solutions (Se concentration 3 mg LE-1, 5 mg LE-1, 10 mg LE-1) then the soaked grains dried in the oven for 24 hours. The total plate count and yeast colony forming units were determined in rye malt samples. The obtained results showed that the increasing of copper and selenium concentration in solution significantly changes microflora of rye malt comparing with the control sample.

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.

The purpose of this study was to evaluate the effect of probiotics, herbals and buckwheat bran (Fagopyrum esculentum L.) on growth, profile of blood, gut microbiota, profile of fatty acid in meat and shedding of resistant Escherichia coli (E. coli) in piglets. A total of 44 piglets (Sus scrofa domesticus) from age of day 14 to 56 were divided into 4 groups. Control received basal diet (group C), basal diet + probiotics (group P), basal diet + 3% buckwheat bran (group PB) and basal diet + 1.5% herbals (group H). No effect was observed in growth in all groups. The count of Lactobacillus spp. increased (p is less than 0.05) in jejunum in group P. In the faeces, Enterobacteriaceae decreased in the group P (p is less than 0.05) of 35 days old piglets, but Enterobacteriaceae and E. coli decreased in the group H (p is less than 0.05) of 56 days old piglets. The prevalence of resistance to at least one antibiotic class was 66.7% before and 50% after the experiment in all groups. Multidrug resistance of E. coli was not observed in 14 days old piglets, but was observed in 50% and more in all of study groups of 56 days old piglets. The fatty acid composition of Longissimus thoracis muscle had higher levels of α-linolenic acid and palmitoleic acid (p is less than 0.05), but lower level of stearic acid (p is less than 0.05) in group P. In conclusion, probiotics and herbals improved gut microbiota, fatty acid profile and affected shedding of resistant E. coli, but not growth performance.