Influence of the Nitrogen Fertilization on the Yield, Biometric Characteristics and Chemical Composition of Stevia rebaudiana Bertoni Grown in Poland.

Stevia rebaudiana Bertoni is a plant native to South America that has gathered much interest in recent decades thanks to diterpene glycosides, called steviosides, which it produces. These compounds are characterised by their sweetness, which is 250-300 times higher than saccharose, and they contain almost no caloric value. Stevia is currently also grown outside the South American continent, in various countries characterised by warm weather. This research aimed to determine whether it is viable to grow Stevia rebaudiana plants in Poland, a country characterised by a cooler climate than the native regions for stevia plants. Additionally, the impact of adding various dosages and forms of nitrogen fertiliser was analysed. It was determined that Stevia rebaudiana grown in Poland is characterised by a rather low concentration of steviosides, although proper nitrogen fertilisation can improve various characteristics of the grown plants. The addition of 100 kg or 150 kg of nitrogen per hectare of the field in the form of urea or ammonium nitrate increased the yield of the stevia plants. The stevioside content can be increased by applying fertilisation using 100 kg or 150 kg of nitrogen per hectare in the form of ammonium sulfate. The total yield of the stevia plants grown in Poland was lower than the yield typically recorded in warmer countries, and the low concentration of steviosides in the plant suggests that more research about growing Stevia rebaudiana in Poland would be needed to develop profitable methods of stevia cultivation.

Analysis of Physicochemical Parameters of Congress Worts Prepared from Special Legume Seed Malts, Acquired with and without Use of Enzyme Preparations.

This study was conducted to produce malt from legume seeds (chickpea, lentil, pea, and vetch) and test whether malting with parameters, typically barley grain, will result in well-modified legume seed malt. Analysis of malt was performed by producing congress worts from legume seed malts. Concentration of phenolic compounds, as well as antioxidant activity of legume seed malts was analysed. Acquired worts were characterised with poor technological characteristics (wort extract, wort volume, saccharification time, brewhouse efficiency); however, the malting process increased concentration of phenolic compounds and antioxidant activity of the plant material. Subsequent mashing tests with addition of different external enzymes and/or gelatinisation of legume seed malt were performed. Use of external enzymes improved saccharification time, extract content, wort volume, as well brewhouse efficiency in the case of some legume seed malts. The best brewhouse efficiencies and highest extract values were acquired by the samples prepared with 30% of gelatinised vetch malt or chickpea malt mixed with 70% of Pilsner malt. The study shows that there is possibility of creating legume seed malts, but malting and mashing characteristics need to be customised for these special malts.