Heavy-Metal Contents and the Impact of Roasting on Polyphenols, Caffeine, and Acrylamide in Specialty Coffee Beans.

Matúš Várady,Katarína Hanková,Peter Popelka,Slavomír Marcinčák,Sylwester Ślusarczyk,Jana Boržíkova,Michaela Vieriková

doi:10.3390/foods10061310

Abstract

The aim of this study was to determine the effect of roasting on the contents of polyphenols (PPH), acrylamide (AA), and caffeine (CAF) and to analyze heavy metals in specialty coffee beans from Colombia (COL) and Nicaragua (NIC). Samples of NIC were naturally processed and COL was fermented anaerobically. Green beans from COL (COL-GR) and NIC (NIC-GR) were roasted at two levels, light roasting (COL-LIGHT and NIC-LIGHT) and darker roasting (COL-DARK and NIC-DARK), at final temperatures of 210 °C (10 min) and 215 °C (12 min), respectively. Quantitative analyses of PPH identified caffeoylquinic acids (CQA), feruloylquinic acids, and dicaffeoylquinic acids. Isomer 5-CQA was present at the highest levels and reached 60.8 and 57.7% in COL-GR and NIC-GR, 23.4 and 29.3% in COL-LIGHT and NIC-LIGHT, and 18 and 24.2% in COL-DARK and NIC-DARK, respectively, of the total PPH. The total PPH contents were highest in COL-GR (59.76 mg/g dry matter, DM). Roasting affected the contents of PPH, CAF, and AA (p < 0.001, p < 0.011 and p < 0.001, respectively). Nickel and cadmium contents were significantly higher in the COL-GR than in the NIC-GR beans. Darker roasting decreased AA content, but light roasting maintained similar amounts of CAF and total PPH.

Highlights

The antioxidant activity of coffee beans depends on the characteristics of phenolic compounds, especially chlorogenic acids (CGA) and caffeine (CAF)
4-O-caffeoylquinic acids (CQA) isomers in our study were highest in the green beans for both coffees, but the content of the 5-O-CQA isomer was much higher in COL-GR than NIC-GR
Total polyphenol contents were higher in COL-GR than the NIC-GR, but the Cd and

Summary

Introduction

The antioxidant activity of coffee beans depends on the characteristics of phenolic compounds, especially chlorogenic acids (CGA) and caffeine (CAF). Both CGA and CAF are important for flavor formation and the healthy effect of coffee brews and their extracts because they reduce oxidative stress and protect the antioxidant system [1,2]. Roasting is the most important operation responsible for the main chemical, physical, and organoleptic characteristics of the final coffee product [6]. The development of AA depends on factors such as time and temperature, the degree of roasting, and the origin of the coffee [8,9]. AA develops early during roasting, reaching a maximum level within a few minutes, and begins to decrease [10]

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