EFFECTS OF PROCESSING CONDITIONS ON THE CASEINOLYTIC ACTIVITY OF CRUDE EXTRACTS OF CYNARA-CARDUNCULUS L

Four processing parameters (time of grinding, pH of buffer, salt conce ntration of buffer, and homogenization time) involved in the liquid ex traction of proteinases from flowers of the wild thistle (Cynara cardu nculus), were studied for their effects on final caseinolytic activity by a surface response method. The caseinolytic activity was assayed s pectrophotometrically using o-phthal-dialdehyde. An empirical quadrati c model was applied to experimental data pertaining to the average enz ymatic activity and equations describing the optimal conditions were o btained. Simultaneous solution of these equations for the local maxima indicated that, within the range tested, the maximum (estimated) spec ific caseinolytic activity (around 9.5 mu mol of equivalent leucine/mi n.g of thistle flower) was obtained by grinding the flowers for 36 s, using an extraction buffer with a pH of 5.9 and a salt content of 0% ( w/w), and homogenizing the ground flower/buffer suspension for 15 min. These data are of use in the optimization of extraction procedures, w hich are of relevance to the production of standardized plant rennets suitable for the large scale manufacture of ewe's milk cheese.