The impact of different filter baskets, heights of perforated disc and amount of ground coffee on the extraction of organics acids and the main bioactive compounds in espresso coffee

Abstract

Espresso coffee (EC) is a complex and much appreciated beverage among coffee consumers. The extraction phase of EC, a combination of physical and chemical variables in a very short time, has a direct effect on the flavour of the beverage. This research aims to optimize the extraction process of EC by decreasing the amount of ground coffee from 14 g to 12 g (double cup), while keeping constant the particle size of ground coffee and the physical parameters of the espresso machine, making use of the following accessories: two different filter baskets, and four different heights of perforated discs (4-7 mm). Quantitative analyses on several organic acids (acetic, citric, caffeic, malic, tartaric) and caffeine, trigonelline, nicotinic and 5-caffeoylquinic acid are carried out with HPLC-VWD through a newly developed method. This combines the quantification of organic acids, obtained through HPLC-VWD, with the results of a sensory panel evaluation on the descriptive notes of EC. The outcomes will trigger and support further studies on different extraction processes, to develop more sustainable and economically affordable coffee of high quality.

Keywords: 5-caffeoylquinic acid (PubChem: CID 5280633); Acetic acid (PubChem: CID 176); Caffeic acid (PubChem: CID 689043); Caffeine (PubChem: CID 2519); Citric acid (PubChem: CID 311); Espresso coffee; Extraction process; Filter basket; HPLC-VWD; Malic acid (PubChem: CID 525); Nicotinic acid (PubChem: CID 938); Organic acids; Perforated disc; Tartaric acid (PubChem: 875).; Trigonelline (PubChem: CID 5570).