Study on the phytochemical properties of pineapple fruit leather processed by extrusion cooking

• Ascorbic acid and flavonoid content of pineapple fruit leather were decreased upto 37% after extrusion cooking.
• The high retention of phytochemical properties of pineapple fruit leather extruded can be obtained at optimal condition.
• The predictive capability of artificial-neural-network modeling is higher than the response surface methodology modeling.

Extrusion cooking process was optimized for development of pineapple fruit leather product using response surface methodology (RSM). Further, image analysis was used as non-destructive quality evaluation technique for extrudate fruit leather. Rotatable central composite design (RCCD) was used to optimize the process parameter in term of total phenolic content, ascorbic acid, total flavonoid and antioxidant activity. The optimal condition of extrusion parameters was obtained as screw speed 70.30 rpm, temperature 68.10 °C and brix 18.0°. In optimal conditions, the experimental values of total phenolic content, ascorbic acid content, flavonoid content and antioxidant activity were 46.91 mg GAE/100 g 51.97 mg/100 g, 48.75 μg of quercetin/g and 95.95%, respectively. In image analysis RGB values of fruit leather were used to establish prediction model using ANN, leading to quantitative estimations of total phenolic content, ascorbic acid content, antioxidant activity and total flavonoid content with higher correlation coefficient. The predictive capability of ANN model was higher than the RSM models. The ANN model predictions lie much closer to the line of perfect prediction than the RSM model.