Evaluation of microwave radiation method for sample preparation of pine needles and wood for carbohydrate analysis

The aim of the current study was to test the suitability ofmicro- wave heating for stopping carbohydrate transformations in plant material. Needles and branches of Pinus sylvestris were treated in microwave oven (2.45 GHz, 800W) and compared to the samples treated in boiling ethanol (96 %). In extracts obtained from the microwaved material the ratio of sucrose to hexoses (glucose and fructose) decreased, while ethanol treatment resulted in stable extracts. The carbohydrate composition in dry samples estimated after a month of storage was persistent. The boiling of needles in ethanol in microwave oven gave the same results as the boiling on a heating plate. In the woody material, differently from the needles, the total concentration of measured carbohydrates depended significantly on the preparation method. In the case of needles, the treatment of plant material in ethanol was better suited for the determination of carbohydrate levels than the microwave treatment.