Usage of Capillary Isotachophoresis and Antioxidant Capacity Measurement in Analysis of Changes in Coffee Properties After Roasting, Steaming and Decaffeination

Abstract

The aim of the study was to optimise and validate the method for quantitation of short-chained organic acids in coffee brews by capillary isotachophoresis (ITP). The linearity of the method was satisfactory with R 2 from 0.9924 for lactic acid to 0.9998 for acetic acid. The limit of detection (LOD) was from 4.9 μmol L −1 for acetic acid to 24.8 μmol L −1 for lactic acid. Precision of the method was from 0.20 to 2.69 %. This method was successfully applied to determine six organic acids (tartaric, formic, citric, malic, lactic and quinic) in Arabica and Robusta green and roasted coffee brews. The roasting as well as steaming and decaffeination processes of beans influenced degradation of acids (citric and malic) and their formation (quinic, tartaric, lactic and formic) in coffee brews. The influence of coffee processing on the antioxidant capacity of coffee brews was also tested by using the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), Folin-Ciocalteu and chelating Fe(II) assays. The roasted coffee brews possessed higher antioxidant capacity than unprocessed coffee brews, excluding chelating activity.

Variation in the Content of Bioactive Compounds in Infusions Prepared from Different Parts of Wild Polish Stinging Nettle (Urtica dioica L.)

“…To select the conditions for the extraction of phenolic compounds and the antioxidant activity, 13 nettle samples were extracted with deionized water using the Response Surface Methodology [29]. For this purpose, spectrophotometric tests were performed with DPPH (2,2 -diphenyl-1picrylhydrazyl) and Folin-Ciocalteu reagents [30]. The workflow diagram can be found in Figure 3.…”

“…The driving current in the preseparation capillary was 250 µA. The initial driving current in the analytical capillary was 50 µA [30]. The structures of the compounds determined using isotachophoresis are presented in the Supplementary Material-Table S3.…”

A meta analysis: the effects of types, roasting degrees and origins on antioxidant properties of coffee

“…FRAP assays were applied to determine the ability of antioxidants to reduce Fe, while ABTS and DPPH assays represented the ability to eradicate radicals (Schouten et al ., 2021). The brew of Arabica beans (51–81%) was shown to demonstrate higher chelation of Fe 2+ ions than that of Robusta beans (31–71%) (Jeszka‐Skowron & Zgoła‐Grześkowiak, 2017). This work suggested that the antioxidant activity of Arabica coffee was higher than that of Robusta, as assessed by FRAP 1, indicating that electron donation by antioxidant compounds in Arabica was higher than that in Robusta.…”

“…(2020) reported a higher content of trigonelline in coffee brewed from Arabica green beans than in coffee brewed from Robusta green beans. Many studies have also found that Robusta coffee has higher antioxidant activity than Arabica coffee (Vignoli et al ., 2011, 2014; Jeszka‐Skowron & Zgoła‐Grześkowiak, 2017) due to the higher amount of caffeine in Robusta (Vignoli et al ., 2014).…”

Recent progress in analytical capillary isotachophoresis

“…The developed procedure can be used for analyses of beer samples from various stages of the brewing process and shows satisfactory accuracy and precision. Jeszka‐Skowron and Zgoła‐Grześkowiak described a method for ITP analysis of organic (tartaric, formic, citric, malic, lactic, and quinic) acids in green and roasted coffee brews. The LODs reached in a column‐coupling system with conductivity detection were from 4.9 μM for HAc to 24.8 μM for lactic acid (LE: 10 mM HCl, β‐alanine, 1% Triton X‐100, pH 3.0; TE: 5 mM propionic acid, pH 3.5).…”