The effect of ultrasound on the hydrolysis of soybean oil catalyzed by phospholipase

Abstract

In this work, soybean oil enzymatic hydrolysis was studied in several operational and reactional conditions using a phospholipase as catalyst. In a first approach, different ultrasound configurations were evaluated and compared to a control reaction. Direct enzyme exposure to ultrasonic irradiation has shown an increment on initial hydrolysis rate but also led to a great enzymatic deactivation and a lower products yield. Reaction performed in two step has shown better results. In this methodology, substrate was pre‐emulsified under ultrasonic irradiation and after that the enzyme was add to start the reaction. In a second approach, surfactant concentration, pre‐emulsification time, enzyme fraction, and oil/water ratio were evaluated. An unexpected behavior was observed on the oil/water ratio experiments. There was a large decrease on the hydrolysis rate around 0.4 oil/water ratio. This phenomenon was thoroughly investigated and it was correlated to the inversion of the continuous phase on the emulsion.Practical applications: Phospholipases can be used as an alternative to conventional lipases for oil modifications in the food/pharmaceutical industry. These reactions are usually slow and can take up days to complete conversion. Ultrasound technology can highly enhance lipase catalyzed oil reaction kinetics, but its application is not fully developed. This paper presents distinct methods to apply the ultrasound on phospholipase catalyzed oil hydrolysis reaction and evaluates several operational conditions. The results obtained in this study can be used to fix operational parameters and reduce the reaction time on the oil hydrolysis reaction.Effect of ultrasound different treatments on the typical hydrolysis profile of soybean oil.