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  • Author: Katarzyna Janda x
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The growth of Thermomyces lanuginosus (TSIKL.) isolates from garden composts and coffee beans on cellulose substrates and xylan at various water activity

Abstract

The study was to determine the effect of water activity (0.850; 0.900; 0.950; 0.995; and 0.999 aw) on the growth of T. lanuginosus on solid media containing different cellulose substrates (crystalline cellulose, carboxymethyl cellulose - CMC, fi lter paper, and sawdust) and xylan. The growth of isolates from coffee beans and garden composts were compared. All isolates did not grow on media with aw < 0.950. On media with aw > 0.950, the hydrolysis zones were only observed on xylan and CMC. The highest daily growth and hydrolysis zone rates were mostly obtained at 0.995 aw and the lowest values were observed at 0.950 aw. The coffee beans isolates at 0.950 aw had the CMC hydrolysis coeffi cient 1.7-times higher than that for xylan. The fungal growth (FG) coeffi cient data indicate that the coffee beans isolates were able to utilize CMC and crystalline cellulose for growth and the highest growth rate was obtained at 0.999 aw. Subsequently, the compost isolates were able to grow on all substrates but the highest growth rate was obtained on CMC at 0.950 and 0.999 aw. Thus, coffee beans and composts provide T. lanuginosus isolates with various growth and hydrolytic zone rates in the range of 0.950−0.999 aw.

Open access
Relationships Between Fungal Contamination and Some Physicochemical Properties of Rapeseeds

Abstract

The aim of this study was to evaluate some properties of rapeseed, to determine the amount of fungi including thermotolerant and xerophilic species and to specify the correlations between some physical properties of rapeseed and the number of fungi. Material was 18 samples of rapeseeds. The characteristics of seeds included volumetric weight, impurities, pH, moisture, water activity, fat content, fat acidity and critical moisture of seeds. Number of fungi were investigated on RBA, YpSs, DG18 medium at 25, 37 and 45°C. Differences between amount of rapeseed impurities and fat acidity have been revealed. The number of fungi was diversified depending on medium and incubation temperature. The largest fungi number was isolated on DG18 at 25°C. Correlations between physicochemical properties of seeds and number of isolated fungi have been pointed out. Our study demonstrated that low pH values and weight by volume of seeds as well as high acidity of fat can be used as indicators of contamination of rapeseeds by fungi.

Open access
Effect of extraction method on the antioxidative activity of ground elder (Aegopodium podagraria L.)

Abstract

In this work the studies on the antioxidative properties of extracts from various morphotic parts of the ground elder (leaves, rhizomes, seeds and flowers) were presented. Moreover, the effect of different extraction methods (ultrasonic assisted extractions, extraction in a Soxhlet apparatus, extraction at the boiling point of the solvent used), solvent and its amount, and extraction time on the antioxidative properties of the obtained extracts were tested. The studies showed that all parts of ground elder can show radical scavenging activity, and it depends mainly on the method of extraction and extraction time. But the most beneficial is ultrasonic assisted extraction which used lower amount of solvent (ethanol). In case of all parts of the ground elder (leaves, rhizomes, seeds and flowers) it allows to obtain very high values of the antioxidant capacity (above 90%) for very short extraction time amounted to 20–40 minutes.

Open access