Parametric and Kinetic Studies on the Storage Stability of Milk Clotting Enzyme

Author : Alcaraz, Aileen Miranda
Major Adviser : Valencia, Jeanne Michelle T.
Major Co-Adviser : Mercado,Susana M.
Committee Members : Alfafara, Catalino G.; Arocena, Rhebner E.
Year : 2017
Month : July
Type : Thesis
Degree: BS
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Abstract

The study aimed to determine the storage pH and temperature that will preserve, if not improve, the milk clotting activity of the enzyme produced by Rhizopus chinensis Saito BIOTECH 3273. Since the saturation of ammonium sulfate added to precipitate the enzyme also affects the milk clotting time, Randomized Complete Block Design with Two Factors was used as a statistical method for analysis of the data. A decrease in pH and in storage temperature resulted to faster clotting times, while an increase in the saturation of Ammonium sulfate added to the milk clotting enzyme resulted to slower clotting times. Faster clotting times were also observed in enzymes with prolonged storage at 10 °C, therefore indicating that the milk clotting enzyme remained stable at these conditions. Results showed that the milk clotting enzyme which was added with Ammonium sulfate with 80% saturation, acidified at pH 3 and stored at 10 °C for five weeks clotted the milk in only about 20.87 seconds. The kinetic parameters of the enzyme with the fastest clotting time were also determined. A Kₘ value of 0.3982 mg/mL and a νₘₐₓ value of 0.0565 mg/mL-s was obtained using the Hanes-Woolf plot. Kₘ value was equal to the reported Kₘ value of pepsin A, and lower to that of chymosin. A faster milk clotting time and lower Kₘ values are desirable in cheese making since it will shorten the time of production.

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