Monitoring of Water Activity in Lactulose-Containing Serum Technology
One of the main ways of enriching whey with prebiotic substances is to modify its composition by membrane electroflotation followed by isomerization. As a result of these processes, a partial transition of serum lactose to lactulose occurs. In this work, we studied the nanofiltration concentration of the lactulose-containing serum obtained by this method in order to clarify the role of osmotic phenomena in this process. The dependence of the filtration rate of lactulose-containing flotated serum on the solids content undergoes a jump at a solids content of 8-10%. This is due to the fact that the boundary layers with a high concentration of lactose contain mainly water bound in hydration shells. Due to the concentration gradient of free water arising on the membrane, it diffuses through the membrane.. Measurement of water activity in lactulose-containing floated whey depending on the concentration of dry matter confirm this assumption. Based on these measurements, an estimate was made of the increase in the concentration of serum in the boundary layer compared to the volume, which turned out to be equal to 3.The effect of whey solids hydration on the filtration rate can be given a theoretical justification in the framework of a quantitative physical model linking filtration rate with water activity. It is established that the use of lactulose-containing food additives based on curd whey in the production of bakery products contributes to the production of a finished product with prebiotic properties. In addition, the use of modified curd whey will enrich the resulting product with minerals.