Effect of in vitro digestion on bioactive compounds, antioxidant and antimicrobial activities of coffee (Coffea arabica L.) pulp aqueous extract

Wiriya Khochapong^a, Sunantha Ketnawa^b, Yukiharu Ogawa^b, Niramol Punbusayakul^a

Department of Food Science, Faculty of Science, Burapha University, Chonburi 20131, Thailand.

Abstract

Effect of in vitro digestion on bioactive compounds, biological activities of coffee pulp extract (CPE) against pathogens and a probiotic (Lactobacillus acidophilus TISTR 1338) was investigated. Total phenolic compound (TPC), chlorogenic acid (CGA), caffeine (CF), total monomeric anthocyanin (TMA), antioxidant and antimicrobial activities of the CPE were determined before and after digestion. After the digestion, the TPC, CGA and CF decreased 7.9, 31.7 and 50.0%, dry weight (dw), respectively. The antioxidant activity decreased 22.6% (DPPH) and 12.4% (FRAP). The CPE inhibited Escherichia coli TISTR 780 and Staphylococcus aureus TISTR 1466 at 150 and 200 mg/mL, respectively. Both CPE and the digested CPE had no effect on the tested probiotics. These results suggest that bioactive compounds of CPE may degrade during in vitro digestion, consequently the antioxidant and antimicrobial properties. Therefore, CPE could be a potential natural antimicrobial for food industry with no effect on the probiotics.

Keywords: Chlorogenic acid, Inhibitory effect, Pathogenic bacteria, Probiotic bacteria.