Ribonucleosides : Interesting nucleo compounds and chemical parameters for characterization of technological treatment of milk and milk products

Ribonucleosides belong to the group of naturally occurring bioactive compounds. They are secreted as metabolic products into physiological fluids. Besides the biochemical and trophochemical properties of dietary ribonucleosides, they exert also effects on in vitro studies using cytochemical systems. Furthermore, different studies report on the use of naturally occurring modified ribonucleosides as suitable pathobiochemical marker molecules. Ribonucleosides, in particular chemically modified ribonucleosides have interesting applications as pharmaceutically active compounds. Considered under nutritional and compositional aspects of milk, ribonucleosides are minor constituents of the non-protein nitrogen fraction. In milk they show a species-specific composition pattern. Some studies report on the influence of technological treatment on the contents of ribonucleosides, and on the activity of the milk enzyme adenosine deaminase, e.g. during milk heat treatment and high-pressure treatment. Different changes of ribonucleoside contents may be used for the characterization of heat treatment, e. g. the formation of N6-methyladenosine is suited for detecting milk heat treatment in the upper range of high temperature pasteurization, the whole range of ultra-high-temperature heating and the normally applied range of sterilization. Furthermore, the determination of ribonucleosides is suitable for the differentiation of butter types. In addition, the milk enzyme adenosine deaminase is an appropriate heat indicator for distinguishing raw milk from thermized and short-time heated milk as soon as short-time heated from high-temperature heated drinking milk.