The objective of this exercise was to introduce students to one of the methods used for determination of the content of pigments’ degradation products in lake bottom sediments characterised by heterogeneous physical and chemical properties. The research revealed that the studied bottom sediments were characterised by diverse content of products produced during degradation of pigments of plant origin, whereas higher concentrations of these compounds were found in sediments containing inorganic carbon (carbonates). The obtained results also indicate that it is important to have the results properly presented, particularly in the case of samples containing the carbonates.
The objective of the proposed experiment was to determine changes in the content of vitamin C in the vegetable material (fresh and processed) during a certain period of time, and to determine the optimal expiry date of a product (in terms of the vitamin C content), as well as to introduce students to common factors adversely affecting the content of vitamin C in food products (with a special emphasis on oxidizing enzymes). The research revealed that regardless of the type of cucumbers (fresh, pickled in brine or in vinegar), the content of vitamin C is rapidly dropping after the destruction of the cellular structure (grating, slicing etc.). In the case of fresh cucumbers, it is a process determined by two factors: release and activation of ascorbinase from the destroyed cellular structure and availability of oxygen. Low pH values in the remaining cases reduce the effect of ascorbinase, and a decrease in the vitamin C content is related to the process of oxidation with atmospheric oxygen.