Effect of extraction pH on techno-functional properties of crude extracts from wild cardoon (Cynara cardunculus L.) flowers

- Properties of C. cardunculus rennet prepared at various pH were investigated.
- The extract at pH 3 had the best milk-clotting properties.
- The enzyme content was determined by densitometry on gels electrophoresis.
- Gels formation was monitored using dynamic rheology and turbiscan.
- The extract prepared at low pH can be employed as an efficient milk-clotting agent.

In the present paper, techno-functional properties of rennet derived from C. cardunculus, prepared at various pH (from 3 to 6), were investigated. It was found that the extract prepared at pH 3 had the best milk-clotting properties (MCA/PA ratio). It presented also the highest enzyme content, determined by densitometry analysis on 1D and 2D gels electrophoresis. Formation of milk gels produced by the extracts and chymosin was monitored using dynamic rheology and turbiscan. It can be assumed that by lowering rennet pH, milk pH decreases, causing a significant increase of curd firmness and both elastic (G′) and viscous (G″) moduli. Results obtained by turbiscan showed similar ΔBS values of gels produced, after 2 h, by chymosin and the crude extract at pH 3. In conclusion, C. cardunculus extract prepared at low pH has the potential to be employed as an efficient milk-clotting agent in the production of dairy products.