Water retention capacity of sugar beet pulp dried by various methods

Abstract

Dried sugar beet pulp should become one of the main ingredients of cattle forage in Ukraine, and so production of such pulp is a very important task, given the necessity of processing by-products of the sugar industry in the absence of large cattle-breeding complexes. Materials and methods. Fresh sugar beet pulp has been used as a food product in a form of an extracted chopped straw of 50 micrometers to 1 mm, with the moisture content of 76 to 80 %. Researches with application of the convection drying method have been conducted in the DNG-9035A drying cabinet. The water retention capacity was determined as a ratio of the amount of water retained by the fibres and remaining in the test tube after centrifuging, and the corresponding amount of dry substances (accuracy ±1 g of water/g of dry substances). Based on the conducted experiment analysis, it has been determined that the pulp dried by the low-temperature method mostly swells in the first 15 to 20 minutes. Within this time period, soaking up to the recovery coefficient β = 0,84…0,89 takes place. The maximum value of the recovery coefficient amounts to 0,93 per 30 minutes for the pulp dried with hot air at the temperature of 100 °С. As a result of conducted experiments, we have determined that the granulated pulp dried under such method swells within the first 20 minutes, whereas the pulp shreds swell within the first 80 minutes. Within this time period, soaking up to β = 0,69 takes place. The maximum value of the granulated pulp recovery coefficient amounts to 0,76 per 35 minutes. However, afterwards, due to mechanical damages in the process of granulation, the product loses its shape completely, and turns into a liquid powder concentrate. The maximum value of the pulp shreds recovery coefficient amounts to 0,78 per 105 minutes. An excessive heat strain per each unit of the material causes considerable destruction of the capillary porous pulp structure, and formation of a crust on the surface, therefore moisture penetration into the material is complicated, and so the liquid interacts with the solid material structure quite slowly. Moisture does not penetrate into destructed cells, and fills open capillaries and pores of the material only. More destructed structure of the pulp facilitates renewal of initial properties as a result of moisture absorption. However, the ability to absorb moisture after drying is one of the necessary conditions determining the quality of final product.