UHPLC-PDA-ESI-TOF/MS metabolic profiling and antioxidant capacity of arabica and robusta coffee silverskin: Antioxidants vs phytotoxins

Abstract

A deeper knowledge of the chemical composition of coffee silverskin (CS) is needed due to the growing interest in its use as a food additive or an ingredient of dietary supplements. Accordingly, the aim of this paper was to investigate the metabolic profile of aqueous extracts of two varieties of CS, Coffee arabica (CS-A), Coffee canephora var. robusta (CS-R) and of a blend of the two (CS-b) and to compare it to the profile of Coffee arabica green coffee (GC). Chlorogenic acids, caffeine, furokauranes, and atractyligenins, phytotoxins not previously detected in CS, were either identified or tentatively assigned. An unknown compound, presumably a carboxyatractyligenin glycoside was detected only in GC. Caffeine and chlorogenic acids were quantified while the content of furokauranes and atractyligens was estimated. GC and CS were also characterized in terms of total polyphenols and antioxidant capacity. Differences in the metabolites distribution, polyphenols and antioxidant capacity in GC and CS were detailed.

Ultrasound‐assisted extraction (UAE) of bioactive compounds from coffee silverskin: Impact on phenolic content, antioxidant activity, and morphological characteristics

“…They showed a wide range TPC from 4.35 mg GAE/g (the coffee blend) to 12.82 mg GAE/g ( coffee robusta ). The results in the present study agreed with those reported by the previous studies (Costa et al, ; Panusa et al, ; Regazzoni et al, ; Toschi et al, ).…”

“…They reported a range of TPC from 0.46 to 0.71 g/100 g CSS. Panusa et al () studied the TPC of the aqueous extracts, with the same solid/liquid radio (1 g/50 mL), from two CSS varieties ( coffee robusta and coffee arabica ) and their blend at 60°C for 30 min. They showed a wide range TPC from 4.35 mg GAE/g (the coffee blend) to 12.82 mg GAE/g ( coffee robusta ).…”

“…Bresciani, Calani, Bruni, Brighenti, and Del Rio () found out the caffeine content extracted by formic acid/water was 1.0 g/100 g sample. Panusa et al () reported the range of caffeine content of two coffee varieties and their blend after aquatic extraction were from 0.28 to 0.37 g/100 g CSS sample. Toschi et al () weekly collected CSS samples in triplicate from a coffee‐roasting company for a total of 5 weeks.…”

“…Many researchers reported CSS extracts had antioxidant activity (Bresciani et al, ; Costa et al, ; Narita & Inouye, ; Panusa et al, ). In present study, two assays, DPPH• scavenging ability and ferric reducing antioxidant power (FRAP), were performed in order to evaluate antioxidant capacity of the CSS extracts under different extraction conditions (solvent, extraction time, and ultrasound intensity).…”

“…Coffee residues contain organic material which make them highly pollutant due to a high demand of oxygen to be degraded, as well as anti‐nutrient compounds (such as caffeine, tannins, and polyphenols) which enable them to be toxic and largely reduce their use in soil or livestock feed applications (Murthy & Naidu, ; Mussatto, Machado, Martins, & Teixeira, ). However, coffee by‐products are high in antioxidant activity and rich in phenolic compounds which can be extracted and further applied in the food and pharmaceutical industries (Jiménez‐Zamora, Pastoriza, & Rufián‐Henares, ; Panusa, Petrucci, Lavecchia, & Zuorro, ). Based on this, the utilization of high added‐value coffee waste can lead to sustainable coffee industry, global economy, as well as a better environment.…”