Lycopene extraction from tomato processing waste using ultrasound and cell-wall degrading enzymes

Abstract

The tomato processing wastes are rich in lycopene pigment, which can be consumed as a natural food colorant and bioactive ingredient. The present study investigates the appropriateness of ultrasound pretreatment and enzymatic treatment with cellulase and pectinase enzymes to extract lycopene pigment from tomato processing wastes using response surface methodology (RSM). To achieve this goal, a central composite design consisting of four independent variables including cellulase concentration (0–10%), pectinase concentration (0–5%), ultrasonic time (0–60 min) and pH (3.5–5.5) was used to examine the influences of these process variables on the lycopene extraction. The second order model of lycopene extraction obtained from RSM analysis had the p value less than 0.001 and represented a coefficient of determination (R2) of 93.82%. Thus, a satisfactorily agreement between experimental and predicted values for lycopene content obtained by the second order model was observed. In addition, the Fourier Transform Infrared spectroscopy results did not show any destruction of functional groups of the investigated extracts containing lycopene pigment. Scanning electronic microscopy images from the remaining tomato processing wastes after treatment with more lycopene content extraction demonstrated more porous structure. These results implied that ultrasound-assisted enzymatic extraction was an efficient extracting method.