Bitterness compounds in coffee brew measured by analytical instruments and taste sensing system

• Published in: Food chemistry Vol. 342; p. 128228
• Main Authors: Fujimoto, Hirofumi, Narita, Yusaku, Iwai, Kazuya, Hanzawa, Taku, Kobayashi, Tsukasa, Kakiuchi, Misako, Ariki, Shingo, Wu, Xiao, Miyake, Kazunari, Tahara, Yusuke, Ikezaki, Hidekazu, Fukunaga, Taiji, Toko, Kiyoshi
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 16-04-2021
• Subjects: Bitterness; Coffee; Coffee - chemistry; Food Analysis - instrumentation; Liquid–liquid extraction; Multivariate Analysis; Projection to latent structure regression; Taste; Taste sensor; Projection to latent structure regression; Taste sensor; Bitterness; Nicotinic acid (PubChem CID: 938); Liquid–liquid extraction; Nicotinamide (PubChem CID: 936); l-Lactic acid (PubChem CID: 107689); Coffee
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2020.128228

•Aim of this study is investigating for bitter compounds in coffee brew.•The results of instrument analysis were subjected to multivariate analysis.•It was suggested that some alkaloids and l-lactic acid contributed to bitterness.•Additional experiment confirmed that these compounds increased the coffee bitterness.
We investigated the bitter compounds in coffee brews using multivariate analysis of the data obtained from analytical instrument and electronic taste sensor experiments. Coffee brews were prepared from coffee beans roasted to four different degrees. Each brew was fractionated into four fractions by liquid–liquid extraction. The relative amounts of 30 compounds in each fraction were analyzed by analytical instruments, and the bitterness response value of each fraction was analyzed by a taste sensor. Candidate bitter compounds in the coffee brews were identified with reference to their variable importance in projection and by coefficient of projection to latent structure regression (PLS-R) analysis. PLS-R analysis suggested that nicotinic acid, l-lactic acid, and nicotinamide contributed to the bitterness of the coffee brews. In fact, the coffee brews with added nicotinic acid, l-lactic acid, and nicotinamide had an increased bitterness response value compared to those without.