Sulčių koncentravimo proceso šaldant tyrimas

Abstract

The aim of the study is to analyze the possibilities of juice concentration by freezing method. Making juice concentration by freezing method does not affect the nutrients, in contrast to the evaporation of water by drying. Fresh vegetable juices are frozen at temperature of -10 oC in freezer. With the first attempt we determine at what temperature and in what period of time water ice crystals formation and growth in juice starts. Then it is possible to optimize the removal of the ice crystals. With the second attempt we freeze juices until the temperature reaches -2.5 °C in it and then we distinguish ice crystals. Viscosity and density of juices is studied by viscometer. Dry matter content is determined from the evaporation of water by drying at temperature of 105 °C to constant weight. Studying the production of concentrated juice by freezing, it was found that the separation of water ice crystals increases the concentration about 2 times in the vegetable juice. In the same time the dry matter content is increased 1.7 times and juice viscosity is increased by 1.12 times. Quality remains unchanged