Purification and Characterization of Milk Clotting Enzyme from Artichoke ( Cynara cardunculus L.) Flowers as Coagulant on White Soft Cheese

摘要

Background and Objective: Global increase in cheese production with decreased supply of calf rennet is leading to search for coagulant alternatives from available resources such as plant extracts. Therefore, the main objective of this study was to extract, purify and characterize Milk Clotting Enzyme (MCE) from artichoke (Cynara cardunculus L. ssp. scolymus) violet flowers and the effect of artichoke crude and purified MCE as a coagulant on chemical, texture profile and sensory properties of white soft cheese compared to calf and microbial rennets during cheese storage were studied to determine the technological suitability of vegetable coagulant for cheese manufacturing. Materials and Methods: The MCE was extracted and purified from artichoke violet flowers. White soft cheese coagulated with artichoke crude extract (CMCE) and Purified Milk Clotting Enzyme (PMCE) compared to Liquid Calf (LC) and Powdered Microbial (PM) rennets were analyzed for chemical, textural and sensorial properties during storage, also the results were analyzed by SAS software using the one way ANOVA procedure for analysis of variance. Results: The CMCE had 425.082 U milk clotting activity per milliliter, yield of partial purified MCE precipitated with 20-40% of ammonium sulfate was 22.58% with 1.32 purification fold, while final recovery yield of PMCE was 17.65% with increase of purification fold up to 1.43. The optimum activity of CMCE and PMCE was at (pH 6.5 and 5.5), respectively and 60°C for both. Moreover, optimal milk clotting activity was observed at 40 and 160 mM of CaCl2 for CMCE and PMCE, respectively. Cheeses made with artichoke MCE exhibited higher levels of acidity and soluble nitrogen content with lower values of cheese yield than those coagulated by LC or PM. Texture profile of CMCE cheese was softer with lower hardness and cohesiveness than those of LC or PMCE. As regards sensorial properties, the flavor and body and texture scores of CMCE cheese were significantly (p<0.05) higher than those with PMCE, LC and PM cheeses, while PMCE cheese had flavor scores close to those produced with LC or PM during storage period. Conclusion: The MCE from artichoke waste could be used as calf rennet alternative in white soft cheese making.