Microwave vacuum drying of pomegranate peel: Evaluation of specific energy consumption and quality attributes by response surface methodology and artificial neural network

Microwave and ultrasound-assisted extraction of bioactive compounds from Papaya: A sustainable green process

The demand for sustainable and eco-friendly extraction methods for bioactive compounds from natural sources has increased significantly in recent years. In this study, we investigated the effectiveness of the microwave pretreated ultrasound-assisted extraction (MPUAE) process for the extraction of antioxidants (TPC, DPPH, and FRAP) from papaya pulp and peel. The optimized variables for the MPUAE process were determined using the Box-Behnken design tool of response surface methodology. Our results showed that the optimized variables for pulp and peel were 675.76 and 669.70 W microwave power, 150 s of irradiation time, 30 °C ultrasound temperature, and 19.70 and 16.46 min of ultrasonic extraction time, respectively. Moreover, the MPUAE process was found to be more energy-efficient and environmentally friendly compared to the conventional ultrasound-associated extraction (UAE) technique. The MPUAE process emitted less CO2 to the environment and had a shorter extraction time, resulting in a more sustainable and cost-effective extraction process. Our study suggests that the MPUAE process has the potential to be a promising and eco-friendly alternative for the industrial extraction of bioactive compounds from papaya and other natural sources.

Antioxidant, Antimicrobial, and Metabolomic Characterization of Blanched Pomegranate Peel Extracts: Effect of Cultivar

Hot water blanching at 80 °C for 3 min can be used as a novel pre-treatment step in pomegranate peel to preserve the integrity of the phytochemical content within the peel extracts by lowering or inactivating enzymes such as polyphenol (PPO) oxidase and peroxidase (POD) that are responsible for the break-down of phytochemicals within the peel. The aim of this study was to investigate the effect of hot water blanching pre-treatment on yield, bioactive compounds, antioxidants, enzyme inactivation, and antibacterial activity of ‘Wonderful’, ‘Acco’, and ‘Herskawitz’ pomegranate peel extracts. We used a variety of spectrophotometric-based assays and liquid chromatography mass spectrometry (LC-MS)-based approach to characterize and quantify metabolites within the peel extracts. Blanching significantly (p < 0.05) reduced PPO activity in all peel extracts, with the highest PPO reduction in ‘Herskawitz’ peel extracts at 0.25 U/mL. Furthermore, higher antioxidant activity in ‘Herskawitz’ blanched peel extracts using 2,2-diphenyl-1-picryl hydrazyl (DPPH) antioxidant activity, ferric ion reducing antioxidant power (FRAP), and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity at 567.78 ± 9.47 µmol Trolox/g DM, 800.05 ± 1.60 µmol Trolox/g DM, and 915.27 ± 0.61 µmol Trolox/g DM, respectively, was noted. ‘Herskawitz’ blanched peel extracts were recorded with the lowest minimum inhibitory concentration (MIC) value of 80 µg/mL for Gram-positive Bacillus subtilis and Gram-negative Klebsiella pneumoniae bacteria strains. A total of 30 metabolites were present in ‘Acco’ and ‘Herskawitz’ peel extracts and were tentatively identified after LC-MS profiling. This study demonstrates that blanched peel extracts from ‘Herskawitz’ cultivar have great potential for commercial use in value-added products in the nutraceutical, cosmeceutical, and pharmacological industries.