Kinetic and Parametric Study of Aqueous Enzymatic Extraction of Soybean Oil

Author : Castro, Maria Hermilyn Oloc-oloc
Major Adviser : Chay, Pham Binh
Committee Members : Abrigo, Casiano S. Jr.; Movillon, Jovita A. 
Year : 1996
Month : April
Type : Thesis
Degree: BS
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An experimental design equation was used to study the predictive effects of the parameter pH, temperature and enzyme concentration on the extraction ability of 2 strain-derived enzyme and comparing it to the observed values of oil yield. A Bacillus subtilis-derived enzyme (Brand name: Neutrase), which is a protease, as well as an Aspergillus aculeatus-derived enzyme (Brand name: Olivex), which is a pectolytic enzyme were used. A second order model with/without interaction term were evaluated employing a complete randomized sampling. Twelve treatments were generated for both type of enzyme. A Multiple Linear Regression technique was used to determine all the constants for the experimental equation and a coefficient of determination (CD) of 97% and 96% were calculated for Neutrase and Olivex, respectively.

Single effects of pH and temperature wee found to be parabolic indicating the existence of an optimum point, while an increasing trend was found at the different enzyme concentration used which confirms the result obtained by Fulbrook that an increasing dosage of enzyme increases the oil yield. The optimum values for every parameter were determined by noting observed oil yield and selecting the maximum values observed.

The optimum points for the Neutrase obtained were: pH = 6.50, Temperature = 50.00 °C and [E] = 3.00 while the optimum points obtained by using Olivex were: pH = 6.00, Temperature = 40°C and [E] = 3.03. These values were then used for the reaction rate determination.

The reaction rate was determined by employing the model described by Levenspiel wherein the plot of Kₒᵦₛₑᵣᵥₑ? versus varying enzyme concentration would give the rate constant for homogenous uncatalyzed reaction as the y-intercept and the slope as the rate constant for homogeneous catalyzed reaction. Four varieties of soybeans with different oil concentration were used to determine the rate constant for the reaction rate of both uncatalyzed and catalyzed reactions.

The kinetic order of reaction was determined by considering the oil yield of untreated substrate (control) obtained in the catalytic reaction time determination and fitting it to a proposed mechanism. The best fitted mechanism and order was that of an irreversible uni-molecular first order reaction.

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