Investigating the Effect of Pulsed Electric Field and Microencapsulation on the Amount of Effective Compounds and Antimicrobial Activity of Hop Plants

Abstract

The research aimed to investigate the impact of pulse electric field–assisted extraction on the extraction yield of effective compounds and the antioxidant activity of hop plants. The study used varying voltages (VPEF: 2000, 4000, and 6000 V/cm) and numbers of pulses (NPEF: 40, 50, and 60) in the extraction process. The results revealed that the extraction efficiency and the antioxidant properties of the extract were affected by the intensity and number of pulses. The optimized conditions for extraction yielded the following results: extraction efficiency of 17.62%, 1280.46 mg GAE/100 g of total phenolic compounds, 3.74 mg/L of α-acids, 5.78 mg/L of β-acids, 77.49% DPPH free radical scavenging, and 529.33 μmol Fe²⁺/g of ferric reducing/antioxidant power. Moreover, the optimized hop extract was microencapsulated by maltodextrin, inulin, and Arabic gum as wall materials. The optimized composition contained 55.8 g/100 g of maltodextrin and 42.2 g/100 g of inulin, leading to better preservation of phenolic compounds with maximum antioxidant activity. The resulting microencapsulated composition had a glass transition temperature of 40.8°C, making it suitable for maintaining effective compounds at ambient temperature. Additionally, the antimicrobial activity of the free and microencapsulated hop extract was observed against Escherichia coli, Staphylococcus aureus, and Aspergillus niger, with greater activity against Gram-positive bacteria than Gram-negative bacteria and fungi.