Hard Cap Espresso Machine Extraction of Polyphenolic Compounds from Pulses

Abstract

A hard cap espresso machine was employed for the extraction of polyphenolic compounds from food samples as dry legumes and pulses. 100 mg of ground dry sample was mixed with a dispersing agent and placed in a refillable stainless steel capsule with a borosilicate filter. A complete polyphenol extraction was achieved by using 150 mL ethanol 50 % (v/v) in water and determined by Folin-Ciocalteu spectrophotometric method. The method provided a limit of detection of 0.4 mg g^-1. The whole extraction procedure was achieved in less than one minute using the mild extraction conditions of 72°C and 19 bars given by the domestic machine. Fifteen varieties of food samples (3 lentils, 6 beans, 5 chickpeas, and 1 sorghum) were purchased in Spanish and Tunisian markets and analyzed by the proposed procedure. Obtained results were compared with those found by a reference extraction method based on ultrasound-assisted extraction, being statistically comparable. The content of polyphenolic compounds in the analyzed commercial samples varied from 4.6 to 5.5 mg g^-1 for lentils, from 3.4 to 5.8 mg g^-1 for beans, from 2.2 to 3.5 mg g^-1 for chickpeas, and 3.0 mg g^-1 for sorghum.