Abstract
In this study, green extraction methods—high voltage electrical discharges (HVED), pulsed electric field (PEF), and ultrasound-assisted extraction (UAE)—were compared in terms of extraction yield of total and individual polyphenolic compounds, as well as the antioxidant capacity of blueberry pomace extracts. All extractions were performed with methanol- and ethanol-based solvents. The highest total polyphenols content (TPC) (10.52 mg of gallic acid equivalent (GAE) per g of dry weight (dw)) and antioxidant activity (AA) (0.83 mmol TE/g dw) were obtained by PEF-assisted extraction in the ethanol-based solvent after 100 pulses and 20 kV/cm, which corresponds to an energy input of 41.03 kJ/kg. A total of eighteen individual polyphenols were identified in all investigated blueberry pomace extracts by high-performance liquid chromatography with the diode-array detector (HPLC-DAD) and liquid chromatography electrospray ionization tandem mass spectrometric (LC-(HESI)-MS/MS). The highest anthocyanin (1757.32 µg/g of dw) and flavanol (297.86 µg/g of dw) yields were obtained in the methanol-based solvent, while the highest phenolic acid (625.47 µg/g of dw) and flavonol (157.54 µg/g of dw) yields were obtained in the ethanol-based solvent by PEF-assisted extraction at the energy input of 41.03 kJ/kg. These results indicated that PEF is a promising green extraction method which can improve the blueberry pomace’s polyphenol extraction yield.
Highlights
Blueberries are very popular fruit due to their numerous health benefits, nutritional value, and excellent sensory evaluation
This study aimed to compare the differences in yield of total and individual polyphenolic compounds and antioxidant activity of blueberry pomace extracts obtained by different methods: high voltage electrical discharges (HVED), pulsed electric field (PEF), and ultrasound-assisted extraction (UAE)
The results of this study have demonstrated that the extraction yield of phenolic compounds from blueberry pomace using High voltage electrical discharges (HVED), PEF, and UAE is dependent on all investigated factors (HVED—solvent, time, and frequency; PEF—solvent, electric field intensity, and number of pulses; UAE—solvent, temperature, and time)
Summary
Blueberries are very popular fruit due to their numerous health benefits, nutritional value, and excellent sensory evaluation. They belong to the group of highly perishable soft fruits with a short shelf life [1]. To prolong the consumption of blueberries throughout the year, they can be preserved or processed into different products. More than 50% of fresh blueberries are processed into some kind of final fruit product; the most important commercial product is juice [2]. Waste generation may be up to 20% of the initial fruit weight [3]. Blueberries contain high amounts of anthocyanins, phenolic acids, flavanols, and flavonols [4], and the evident fact is that these
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