Experimental Design of the Interaction Effect of Independent Variables on Pineapple (Ananas comosus) Fruit Bromelain Activity

Abstract

Background: Certain factors are known to influence the rate of enzyme activity. It is paramount to study such independent factors to obtain the ideal conditions required to maximize enzyme activity. The time-consuming traditional one-factor-at-a-time (OFAT) approach of evaluating the effect of independent variables on enzyme activity does not consider the interaction effects of the independent variables on dependent responses. Methods: The impact of four independent variables on fruit bromelain activity was evaluated using the complete factorial design of the experiment approach. Results: The highest actual fruit bromelain activity (76.83 U/ml) and predicted activity (74.81 U/ml) were recorded at an optimum pH of 7.5, temperature of 50oC, and incubation period of 10 minutes using azocasein substrate. All tested variables except temperature; the interaction between substrate type and incubation time significantly affected fruit bromelain activity (p < 0.05). Conclusion: The design model analysed the main and interaction effect of the variables on bromelain activity. Therefore, complete factorial design is a better approach than OFAT to determine the effect of independent variables on fruit bromelain activity.