Effects of High Pressure-Assisted Extraction on Yield, Antioxidant, Antimicrobial, and Anti-diabetic Properties of Chlorogenic Acid and Caffeine Extracted from Green Coffee Beans

Abstract

The bioactive ingredients of green coffee beans were extracted using high pressure-assisted extraction (HPE) and compared against those derived from the traditional heat reflux (HR) extraction method. The effect of extraction conditions on the extraction efficiency of functional components (chlorogenic acids, caffeine, total phenols, and flavonoids); the free radical-scavenging activity of the extract; and the inhibition of α-glucosidase, α-amylase, and food pathogenic bacteria were measured. Using water as the solvent, the high-pressure extraction rates of chlorogenic acid (CGA) and caffeine were 3.20–5.75 mg/100 g and 4.32–7.95 mg/100 g, respectively, which were significantly higher than the rates obtained using the traditional method (2.92 mg/100 g and 3.54 mg/100 g, respectively). Under optimal extraction conditions of 25 °C and 600 MPa for 2.5 min, inhibition of α-glucosidase and α-amylase by the extract reached rates of 27.8% and 26.7%, respectively, with the highest free radical-scavenging activity of 81.5%. HPE exhibited antibacterial activity against both gram-positive (Staphylococcus aureus and Listeria innocua) and gram-negative (Escherichia coli and Salmonella enterica) bacteria, and the lowest minimum inhibitory concentration (4.69 mg/mL) against S. aureus was achieved. Scanning electron microscopic observations evidenced that high pressure partially damaged the intercellular compartments of coffee beans, increased solvent permeability, and improved the extraction rate of bioactive ingredients. The outcomes of the study demonstrated that HPE can be employed as an efficient extraction technique for production of chlorogenic acids and caffeine that might have a potential application in food and related industries.