The influence of solvent, storage time and temperature on the stability of the mycotoxin sterigmatocystin (STC) was investigated. STC calibrants (1.0 μg mlE-1) in acetonitrile, methanol and mixture of acetonitrile and methanol (50:50, volume/volume) were stored in dark glass bottles at (– 25), 4 and 25 °C for up to 8 weeks. Samples were analysed by high performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Obtained results indicate that more suitable solvents for storage of STC standard solutions at (–25 °C) are acetonitrile and mixture of acetonitrile and methanol (50:50, v/v), but not longer than for one week; for storage at 4 °C more suitable is mix of acetonitrile and methanol, but not longer than for one week.

The aim of the present study was to determine the concentration of microscopic fungi and selected mycotoxins in fresh bee pollen, stored for different periods. In the study, 12 pollen samples collected from the same apiary families were investigated. The total count of microorganisms in the pollen during the study period varied from 2.9×103 to 4.4×103 cfu g-1. The moisture content of fresh pollen varied between 14.2 and 22.7%. During studies, the most prevalent fungal genera of Fusarium, Penicillium, Alternaria, Mucor and yeast were found in fresh bee pollen. The amounts of microscopic fungi increased from 2.9×103 to 4.4×103 cfu g-1 as the pollen storage time increased. The significantly higest amounts of fungal colonies was determined after 3 days storage of undried pollen. The most significant Fusarium spp. increase (14.9%) was determined after 2 days of storage. The highest levels of mycotoxins ZEN and DON were determined after 3 days of pollen storage. Fresh bee pollen chould be dried as quickly as possible, to reduce the levels of microbial contamination.

The aim of this study was to evaluate the effect of Saccharomyes cerevisiae, Geotrichum fermentans, Rhodotorula rubra and Kluyveromyces marxianus yeast cell suspensions and Saccharomyces cerevisiae cell wall’s polysaccharides and fermentation time on mycotoxins concentrations in feed wheat. The 2018 harvest three feed wheat samples were taken from grain processing companies and the research was carried out at the Lithuanian University of Health Sciences, Veterinary Academy, Mycotoxicology Laboratory. The thin – layer chromatography technique (TLC) was used to determine mycotoxins concentrations in the samples. The wheat samples were inoculated with Saccharomyces cerevisiae, Geotrichum fermentans Rhodotorula rubra and Kluyveromyces marxianus yeast 104 cells` ml-1 suspensions and Saccharomyces cerevisiae cell wall`s polysaccharides, duration of the wheat fermentation with the yeast was – 30 min. and 60 min. It was found that all species the yeast suspensions – reducing effect of mycotoxins concentrations correlated with longer duration of fermentation. Saccharomyces cerevisiae yeast suspension after 60 min. reduced AFB1 and DON by 100% (p<0.05) and ZEA up to 80.1 ± 0.50% (p<0.05). Saccharomyces cerevisiae yeast cell wall`s polysaccharides decreased the concentrations of AFB1 (p>0.05), ZEA (p<0.05), DON (p<0.05) during the experiment better than Saccharomyces cerevisiae 104 cells` ml-1 suspension and after 60 min. exposure polysaccharides absorbed all wheat mycotoxins by 100% (p<0.05). The AFB1 were best absorbed by Kluyveromyces marxianus yeast after 60 min. of fermentation by 100% (p<0.05). The DON concentration was below the detection limit after 60 min. of fermentation with Geotrichum fermentans and Rhodotorula rubra yeast.

Sterigmatocystin is a mycotoxin produced by fungi of many Aspergillus species and it is a biogenic precursor of aflatoxin B1. For analysis of various mycotoxins to clean up sample extracts, mainly solid phase extraction (SPE) is used. An elution of sterigmatocystin from Strata X and Strata C18 SPE columns by different acetonitrile-water and methanole-water solutions were checked in this paper. Acquired results showed a possible suitability of both columns for the analysis of sterigmatocystin.