Application of Multivariate Analysis to the Effects of Additives on Chemical and Sensory Quality of Stored Coffee Brew

Abstract

The aim of this work was to obtain a black coffee brew to be consumed hot by extension of its shelf-life, by addition of additives. Four pH-regulator agents (sodium and potassium carbonates and bicarbonates), one pH-regulator and antioxidant (sodium citrate), three antioxidants (sodium ascorbate, ethylenediaminetetracetic acid (EDTA), and sodium sulfite), and lactoserum were tested by sensory analysis. Sodium carbonate and bicarbonate were selected for a study of the physico-chemical (soluble and volatile compounds related to the sensory properties) and sensorial quality of coffee brew stored during 90 days at 4ºC.Although both additives extended the shelf-life of the coffee brew up to 60 days, sodium carbonate was the chosen additive because it was the most useful in limiting the pH decrease and perception of sourness, which are some of the main factors involved in the rejection of stored coffee brews, and maintain better the aroma and taste/flavor. Moreover, the application of multivariate analysis facilitated, firstly the description of the global changes of the coffee brews with or without additives throughout the storage using the Principal Component Analysis (PCA), and secondly, to obtain a simple equation only with pH and caffeic acid parameters to discriminate the three types of coffee brews and simplify the analytical process, by means of the Stepwise Discriminant Analysis (SDA).

Effect of sugar addition (torrefacto) during roasting process on antioxidant capacity and phenolics of coffee

“…A Hypersil-ODS column (5 μm particle size, 250 mm × 4.6 mm) was used. The chromatographic separation was achieved at 25 ºC by using a gradient solvent system with acetonitrile/water adjusted to pH 3.0 with a phosphoric acid solution according to the method described by Perez-Martinez, Sopelana, De Peña, & Cid (2008). The wavelength of detection was 325 nm.…”

“…The HPLC analysis was carried out with the same equipment and column described above. The chromatographic separation was achieved at 25 ºC by using a gradient solvent system with acetonitrile/water adjusted to pH 2.5 with a phosphoric acid solution according to the procedure published by Perez-Martinez et al (2008). The wavelengths of detection were 314 nm for caffeic acid, 325 nm for ferulic acid and 210 nm for 4-vinylguaiacol.…”

Influence of Brewing Method and Acidity Regulators on the Antioxidant Capacity of Coffee Brews

“…The selection of the additives and their concentrations were reported in a previous paper (33). pH and Total Solids.…”

“…In this type of products, other ingredients or additives, mainly milk derivatives, are usually added to preserve the coffee brew quality, but no studies regarding their influence on the antioxidant capacity have been found. In a previous work carried out by our research group, the addition of sodium carbonate or sodium bicarbonate, as pH-regulator agents, to black coffee brews has been proposed to extend the shelf life (33).…”

“…The selection of the additives and their concentrations were mainly based on sensorial parameters and reported in a previous paper (33). Sodium carbonate (75 ppm) and sodium bicarbonate (75 ppm) water solutions were used as blanks and no reactions in any of the antioxidant capacity parameters were observed.…”