Optimization of process parameters for mechanical extraction of banana juice using response surface methodology

Banana juice is traditionally processed under very basic conditions characterized by low efficiency and poor hygiene. Introduction of mechanical pressing has created opportunities for upgrading banana juice production, but more knowledge is needed about critical factors for juice release and about optimizing extraction for higher yield and quality. This study sought to identify and optimize important factors associated with juice release. This was done using an experimental design (Box-Behnken design of response surface methodology) involving three levels of three independent variables: blending speed (1000-3500 rpm), extraction time (30-240 s), and stage of ripeness (3-7). A second-order polynomial equation was created to describe the relationship between dependent and independent variables. The results showed that juice yield increased with blending speed, extraction time, and stage of ripeness, whereas the quadratic (squared) effect of these factors was a significant decrease in juice yield. Optimum juice yield (57.5%) was obtained at blending speed 2650 rpm, extraction time 162 s, and ripeness stage 5. Analysis of variance showed that stage of ripeness significantly (p ≤ 0.001) affected juice yield. This novel information on the underlying factors in banana juice extraction and on optimization of the process can be used to improve mechanical extraction of low-viscosity, clear banana juice and achieve scaling-up of banana juice processing.