Indicadores químicos do envelhecimento de café arábica durante o armazenamento

Abstract

During storage of green coffee beans, metabolic changes occur, affecting the sensory quality of the product. Jute bags are the most used packaging form worldwide. However, jute bags are permeable, which provides greater exposure of coffee to environmental conditions favoring further reduction of quality. Currently, no packaging in use has the ability to maintain the initial quality of the coffee beans, which is usually described as having flavor and aroma characteristic of old coffee. This reduction in quality has a great impact on the specialty coffee market, since, depending on the intensity of these characteristics, the beverage is no longer considered special. Most of the green coffee storage studies use specific analytical techniques for certain groups of chemical compounds to explain the phenomenon of grain aging. However, the dynamics of transformations occurring in the grains during storage is complex and is not limited to changes in specific chemical groups, leaving a ga p about the compounds responsible for altering the taste or aroma of the beverage. It is thus believed that modern methodologies of food analysis capable of providing a complete analysis of the chemical compounds have high potential to clarify the phenomenon, bringing benefits to the management and control of the specialty coffee industry. In this context, the present study used spectroscopic and chromatographic techniques to address the phenomenon of Arabica coffee beans aging. The study was divided into t hree articles with the objective of determining chemical indicators of the aging of Coffea arabica L. green coffee before affecting their sensorial quality, by using using (i) Raman spectroscopy and (ii) 1 H NMR spectroscopy to analyze green coffee beans and (iii) Gas chromatography mass spectrometry (GC/MS) in roasted and ground beans. Green coffee beans of specialty natural and specialty pulped natural coffee were packed in 3 different types of packaging and stored in commercial warehouse. Sensorial, spectroscopic and chromatographic analyzes were carried out at 0, 3, 6, 9, 12 and 18 months of storage. The use of Raman spectroscopy with multivariate control charts, based on PCA was efficient in identifying chemical changes in the green coffee beans of pulped natural coffee stored in different packages. Raman spectroscopy is more sensitive than sensory analysis to detect chemical changes in pulped natural coffee, which might affect the quality of the beverage. The metabolomic approach using NMR spectroscopy w as efficient in identifying chemical changes related to the aging of green coffee beans of natural and pulped natural coffee before affecting the sensory quality of the beverage. The analysis of the volatile compounds present in roasted coffee beans was efficient in identifying chemical changes in green coffee beans of natural coffee stored in different packages. Spectroscopic and chromatographic techniques were efficient in detecting changes related to the aging of Arabica coffee beans prior to sensorial depreciation. The high-barrier packaging offers the same protection to coffee as the vacuum packaging and is suitable for the packaging of green coffee for up to 18 months.