Ultrasound and supercritical fluid extraction of phytochemicals from purple tamarillo: Optimization, comparison, kinetics, and thermodynamics studies

Abstract

The parameters for extraction of phenolic compounds and anthocyanins in purple tamarillo using supercritical fluid (SCFE) and ultrasound-assisted extraction (UAE) techniques were optimized. Optimizations of extraction techniques were done using Box-Behnken design in response surface methodology. Based on the total phenolic content, the experimental range for the independent variables in SCFE was set at 30 to 60 min, 40–60 °C, and 150 to 180 bars of pressure (TPC). Similarly, for UAE, the selected independent variables were 10–30 min time, 40–60 °C temperature and 20–60% amplitude. The optimized conditions for SCFE were determined to be 49.42 min, 49.28 °C and 176.63 bar pressure, and at the optimized parameters, the TPC was 16.12 mg GAE/g and anthocyanins was 0.62 mg C3G/g in the extract. The optimized parameters for UAE were 19.14 min, 51.53 °C, and 50.53% amplitude, which yielded 21.06 mg GAE/g TPC and 0.71 mg C3G/g anthocyanins. Four phenolic acids (gallic acid, chlorogenic acid, caffeic acid, and p-coumaric acid) and three anthocyanins (delphinidin-3-O-rutinoside, cyanidin-3-O-rutinoside, and pelargonidin-3-O-rutinoside) were identified by HPLC in both the extracts. However, higher concentration of phenolic acids and anthocyanins were extracted by UAE as compared to SCFE. SEM morphology of sample matrix showed extensive disintegration after UAE process. The optimized extract can be used in the food industry as a natural colorant in place of synthetic pigments that are bad for customers' health and wellbeing. The extract also can act as a source of potential antioxidants and can be used in the development of new functional foods.

Keywords

• Tamarillo
• Response surface methodology
• HPLC
• Extraction
• Phenolic acids
• Anthocyanins