Contribution of phenolic acids isolated from green and roasted boiled-type coffee brews to total coffee antioxidant capacity

Abstract

50 % (on average over 36 and 45 % in green and roasted coffee extracts, respectively). Significant differences between the AC values determined for CB and PA samples were noticed only for the MCA and DPPH methods which reflect the different molecular mechanisms underlying each of the assays. Additionally, the statistical methods, including principal component analysis, applied to results of antioxidant capacity obtained with different analytical techniques confirmed their feasibility to distinguish between coffee brews with different degrees of roasting, regardless of coffee origin. Abstract The antioxidant capacity (AC) of boiled-type coffee brews (CB) and phenolic acids (PA) isolated from them, obtained from the caffeinated and decaffeinated beans of different geographical origins and species and with different roasting degrees, was examined. The AC of PA and CB samples was tested in five antioxidant assays: a total antioxidants reducing capacity assay using a Folin-Ciocalteu reagent (FCR), a ferric ion reducing antioxidant power (FRAP) assay, a DPPH · radical-scavenging activity (DPPH) assay, a metal chelating activity (MCA) assay and a total radical trapping antioxidant parameter (TRAP) assay. In most samples, the total amount of phenolic acids, determined by HPLC, decreased with the increasing degree of roasting the coffee beans, leading to reduced AC. All used methods showed that CB exhibits higher AC compared with the PA samples. Phenolic acids isolated from CB samples have the main contribution (on average over 95 and 84 % in green and roasted coffee extracts, respectively) in AC of the CB samples in FCR, FRAP and TRAP assays, whereas in DPPH and MCA tests, the phenolic acid contribution in AC of CB samples was below Keywords

Ochratoxin A, fungal contamination and antioxidant property of defective Arabica coffee in Benguet, Philippines

“…However, it was observed that roasted non-defective coffee beans exhibited significantly higher antioxidant activities compared to roasted defective coffee beans. The results in this study agrees with the study of Górnaś et al (2016), indicating a lower contribution of phenolic compounds to metal chelating activities of roasted coffee bean extracts.…”

“…It has to be noted that other notable compounds which have been extensively published elsewhere regarding other contents of coffee extracts such as phenolic compounds (Ramalakshmi et al, 2009;Górnaś et al, 2016), biogenic amines such as putrescine, cadaverine, spermidine, spermine and tryptamine (Vasconselos et al, 2007), proteins, carbohydrates, fatty acids (Oliveira et al, 2006), several volatile compounds (Toci and Farah, 2008) and diterpenes such as cafestol and kahweol (Cavin et al, 1998). However, unwanted contaminants such as mycotoxins may also be present (Taniwaki et al, 2014).…”

“…The reduction of total phenolic content in roasted coffee samples was generally attributed to roasting due to the thermal instability of phenolic compounds (Górnaś et al, 2016). This explains why roasted coffee samples had lower total phenolic content compared to green coffee bean samples.…”

“…Coffee is globally recognized as a popular beverage with well-documented in vitro antioxidant activities (Ramalakshmi et al, 2009;Liang and Kitts, 2014;Górnaś et al, 2016). In the Philippines, Benguet ranks third among the provinces in the Cordillera Administrative Region with the highest coffee production, with Arabica coffee variety grown in backyard or commercial coffee farms (Culliao and Barcelo, 2015).…”

Effect of roasting degree on the antioxidant activity of different Arabica coffee quality classes

“…Samples of 1 st class Arabica coff ee roasted at 171°C had signifi cantly higher (P < 0.05) antioxidant activity (DPPH) than coff ee samples roasted at 167°C and 175°C. Górnaś et al (2016) found that antioxidant activity (DPPH) decreases during the roasting process and is higher in medium-roasted coff ee samples than in dark-roasted coff ee samples. Antioxidant activity based on the results of the ABTS test was highest in 1 st class Arabica coff ee roasted at 167°C, and lowest in coff ee roasted at 175°C (Table 5).…”