Screening of the process parameters for vacuum microwave-assisted extraction of bioactive compounds from amaranth flowers

Abstract

In this study, a series of trial experiments were carried out to determine the optimal extraction parameter ranges for betalains, phenolic compounds, and antioxidants from amaranth (Amaranthus caudatus L.) flowers during the vacuum-microwave extraction (VMAE). VMAE reduces thermal degradation and oxidation risks compared to traditional extraction methods, improving extraction efficiency for thermosensitive and oxygen-sensitive compounds. Since there is no prior study in the literature about optimisation of the extraction conditions of vacuum microwave-assisted extraction of betalains and other bioactive materials in amaranth flowers, this pre-study was essential. The experimental plan was designed according to different ethanol concentrations (20%-40%-60%), extraction periods (5-8-12 min), and pressures (100-450 mmHg). Subsequently, the total betalain content (TBC), total phenolic content (TPC), and total antioxidant capacity (TAC) values were measured. The aim was to identify the minimum and optimal conditions for extracting bioactive compounds using the VMAE method for further optimization studies. The experimental results showed that for the maximization of TBC, the conditions were 40% ethanol concentration, 8 min, and 450 mmHg pressure. Conversely, for the maximisation of TPC and TAC, the conditions were 20% ethanol concentration, 12 min, and 450 mmHg pressure. Scanning Electron Microscopy (SEM) analysis was performed to understand the general effects of VMAE on the morphology of the flower samples. These findings provided valuable insights for the future optimisation of extraction processes from amaranth flowers or similar betalain-containing plants using VMAE, contributing to the enhancement of extraction efficiency and the potential utilization of these bioactive compounds in various food applications.

Keywords

• Green Extraction Methods
• Nutraceuticals from Amaranth
• Antioxidant Capacity
• Amaranthus caudatus L.
• Betalains
• Phenolic compounds
• Scanning electron microscopy

Supporting Institution

TÜBİTAK

Project Number

222O444

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