Clotting characteristics of milk by Withania coagulans: Proteomic and biochemical study

ABSTRACT

Extract of Withania coagulans fruit was evaluated for milk clotting activity. The highest enzyme activities were detected at pH 4 and 65°C. A 50 mM CaCl₂ was considered sufficient to decrease the milk clotting activity to an effective level. Rennet coagulation time was steadily increased with increasing NaCl and decreasing enzyme concentrations. The enzymatic activity of extract was completely inhibited by pepstatin-A, an aspartic protease inhibitor. Proteomic and zymographic analysis discovered an aspartic protease with Mw of about 35 KDa and pI of 5.91. Our data demonstrated that use of this plant in traditional cheese making has the scientific bases due to existence of an effective protease.

KEYWORDS:

• Withania coagulans
• Rennet coagulation time
• Ammonium sulfate fractionation
• Aspartic protease
• Two-dimensional electrophoresis

Acknowledgments

This study was conducted at the Research Center of Medicinal and Ornamental Plants, University of Zahedan, Iran. The authors wish to thank Dr. DM Kordi Tamandani for their kindly help and scientific cooperation.