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. 2021 Jan 25;26(3):613.
doi: 10.3390/molecules26030613.

Improving the Recovery of Phenolic Compounds from Spent Coffee Grounds (SCG) by Environmentally Friendly Extraction Techniques

Ilhami Okur  1   2 , Betul Soyler  1 , Purlen Sezer  1 , Mecit Halil Oztop  1 , Hami Alpas  1
Affiliations

Improving the Recovery of Phenolic Compounds from Spent Coffee Grounds (SCG) by Environmentally Friendly Extraction Techniques

Ilhami Okur et al. Molecules. .

Abstract

The aim of this study was to investigate and compare the effects of different extraction techniques (high hydrostatic pressure-assisted extraction (HHPE), ultrasound-assisted extraction (UAE), and classical solvent extraction (CSE)) on phenolic compounds from spent coffee grounds (SCG). Different HHPE parameters (300, 400 and 500 MPa at 25 °C for 5, 10 and 15 min) and UAE parameters (40%, 50%, and 60% amplitude at 25 °C for 5, 10 and 15 min) were used. These techniques were compared with CSE (at 50 °C for 30 min) according to total phenolic content (TPC), antioxidant activity (AA), high-performance liquid chromatography (HPLC), scanning electron microscopy (SEM), and infrared (IR) spectroscopy. The results showed that eco-friendly techniques increased the TPC and AA compared to CSE and morphological changes were verified by SEM results. Furthermore, chlorogenic and caffeic acid were also quantified by using HPLC. Chlorogenic acid was found as the main phenolic compound in spent coffee grounds (SCG). The highest chlorogenic acid was detected as 85.0 ± 0.6 mg/kg FW with UAE at 60% amplitude for 15 min. In brief, for the extraction of phenolic compounds from waste SCG eco-friendly techniques such as HHPE and/or UAE were more convenient than CSE.

Keywords: high hydrostatic pressure-assisted extraction (HHPE); phenolic compounds; spent coffee grounds (SCG); ultrasound-assisted extraction (UAE).

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Conflict of interest statement

The authors declare that there are no conflict of interest.

Figures

Figure 1
Figure 1
TPC results of different extraction techniques (A) HHPE treatment (B) UAE.
Figure 1
Figure 1
TPC results of different extraction techniques (A) HHPE treatment (B) UAE.
Figure 2
Figure 2
DPPH assay results of (A) HHPE treatment (B) UAE.
Figure 3
Figure 3
FRAP results of different extraction techniques (A) HHPE treatment (B) UAE.
Figure 4
Figure 4
HPLC chromatograms (A) Chromatogram of phenolic standards (B) Chromatogram of phenolic from SCG extracted by CSE (C) Chromatogram of phenolic from SCG extracted by HHP treatment (500 MPa for 15 min) (D) Chromatogram of phenolic from SCG extracted by UAE (60% Amplitude for 15 min).
Figure 5
Figure 5
Infrared (IR) Spectrum results. UAE (60% Amplitude for 15 min), HHPE (500 MPa for 15 min), CSE.
Figure 6
Figure 6
SEM results (A) CSE (B) HHPE (500 MPa for 15 min) (C) UAE (60% Amplitude for 15 min).
See this image and copyright information in PMC

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