Onopordum acanthium L. (Asteraceae) flowers as coagulating agent for cheesemaking

By trituration in liquid nitrogen, homogenization in 0.1 mol/L citric acid-sodium citrate buffer (pH 3.0) containing 1.0 mmol/L EDTA, and centrifugation (10000 × g) of fresh Onopordum acanthium L. (Asteraceae) flowers, a proteolytic preparation (“onopordosin”) was obtained (pI 4.4), which showed proteolytic and clotting activity (0.546 ± 0.004 Rennet Units/g flowers and 0.090 ± 0.003 Endopeptidase Units/g flowers, respectively) at acid pH values, conditions that favor its use in cheese manufacturing. Hydrolytic behavior (SDS-Tricine PAGE) of onopordosin was compared with that of chymosin in bovine milk clotting assays. Onopordosin was used as vegetal coagulant with pasteurized bovine milk to manufacture a semi-hard type cheese which was analyzed by sensory panelists at the Experimental Superior Institute of Food Technology in Argentina, who evaluated different parameters and concluded that the quality of the cheese made with onopordosin was similar to that of commercial cheeses.

► A new protease (“onopordosin”) was obtained from Onopordum acanthium L. flowers. ► Proteolytic activity was due to an aspartic proteinase (45 kDa and pI 4.4). ► Hydrolytic behavior of onopordosin and chymosin was compared in milk clotting assay. ► Onopordosin was used as vegetal coagulant to manufacture a semi-hard type cheese. ► Quality of cheese made with onopordosin was similar to that of commercial cheeses.