Abstract
<p>Chlorogenic acids (CGA) are a group of phenolic acid derivatives, which are commonly found in coffee at concentrations reaching 0.1-0.2%. A method based on high performance liquid chromatography-diode array detector (HPLC-DAD) is proposed for the simultaneous determination of three chlorogenic acids, i.e. 3-<em>O</em>-caffeoylquinic acid (3-CQA), 5-<em>O</em>-caffeoylquinic acid (5-CQA) and 3,5-di-O-caffeoylquinic acid (3,5-diCQA), in time portions of espresso coffee. Two different espresso coffee machines working with different pressure and temperature curves, and two different blends (i.e. Arabica and Robusta) were used. The method presents good linearities (correlation coefficient greater than 0.99) and recoveries (in the range 67-99%) for the 3 chlorogenic acids. The concentration of total CGAs in a cup of Certified Italian Espresso ranged from 1522.5 to 2223.4 mg kg<sup>-1</sup> and CGA isomer contents were, in decreasing order, 5-CQA &gt; 3-CQA &gt; 3,5-diCQA.</p> <p>The concentration of total chlorogenic acids was higher in Espresso coffee (EC) prepared with Aurelia machine rather than with Leva; Arabica blend possessed higher level ot total chlorogenic acids than Robusta samples. <strong></strong></p>
Highlights
Brew coffee is a very popular beverage in the world (Parliament & Stahl, 1995)
By comparing the trends of chlorogenic acids concentration obtained with Arabica, the total concentration is higher in samples obtained using Aurelia rather than Leva in the first three fractions
It is clear that similar trends for the concentration of Chlorogenic acids (CGA) have been obtained for different coffee blends made with the same espresso machine, even if the total concentration of the three compounds is slightly higher in Arabica than in Robusta especially in the first three fractions
Summary
Brew coffee is a very popular beverage in the world (Parliament & Stahl, 1995) Consumers appreciate this drink for its enjoyable aroma, appreciable directly through the nose. To prepare a Certified Italian Espresso the following technical conditions are reported in literature, though only those would not be sufficient to completely fulfill quality requirements: needed portion of ground coffee of 7 g ± 0.5, temperature of water coming out from the unit of 90°C ± 2°C, coffee temperature in the cup of 67°C ± 3°C, water pressure of 9 bar ± 1, percolation time of 25 seconds ± 2.5, viscosity at 45°C > 1.5 mPas, total fat > 2 mg/ml, caffeine < 100 mg/cup, volume in the cup (inclusive of foam) 25 ml ± 2.5 (Odello & Odello, 2006). Caffeoylquinic acid derivatives, like 3-O-caffeoylquinic acid (3-CQA), www.ccsenet.org/jfr
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