Degradation of caseins from milk of different species by extracts of Centaurea calcitrapa

Two purified aqueous extracts of Centaurea calcitrapa, a plant from the Compositae family, were shown to degrade bovine, ovine, and caprine milk caseinates. The corresponding hydrolysis patterns were monitored by urea-polyacrylamide gel electrophoresis and compared with those of a commercial mixture of chymosin and pepsin. The plant proteases degraded both α_s- and β-caseins more extensively than the commercial rennet, thus yielding proteolytic patterns where different specificities toward such substrates are apparent. The animal rennet was found to display the greatest clotting power per milligram of protein but the least specificity toward ovine and caprine caseins. It is, therefore, suggested that the said plant extracts be used as an alternative to commercial animal rennets especially in the manufacture of caprine and ovine milk cheeses.