Coffee Analysis
The success story of coffee started in the 15th century, and to this date it maintains its status as one of the most popular beverages, with millions of coffee drinkers all around the world. The black brew is made from ripe berries which are picked from the coffee plant, processed and dried. Once dry, these „beans“ are roasted and ground to be brewed into the coffee drink we all know and love. Over the centuries, coffee has grown into one of the world's most beloved hot beverages and become part of our lifestyle and even cultural phenomena. With a total consumption of approximately 10 million tons of coffee beans per year, coffee is one of the most consumed beverages worldwide because of its stimulating properties and intense aroma and flavor. The coffee aroma is one of the most complex one’s within the world of food, with more than 1000 volatiles identified in roasted coffee beans.
Despite the high number of volatile compounds, only around 40 have been identified as main aroma impact compounds. However, the determination and identification of aroma compounds in low concentration levels is challenging in terms of analytics and therefore, an analytical approach with high selectivity and low limits of detection is required.
Defining the coffee aroma
The secret to good coffee is the sulphur compounds
With a total consumption of approximately 10 million tons of coffee beans per year, coffee is one of the most consumed beverages worldwide. This popular drink is not only appreciated for its stimulating properties, but also for its pleasant and intense aroma and flavour. There have been more than 1,000 volatiles identifed in roasted coffee beans, making it one of the most complex aromas in the world. The reaction of reducing sugars and amino acids (known as the Maillard reaction) at elevated temperatures generates numerous compound classes; these include aldehydes, diketones, and heterocyclic compounds with nitrogen, oxygen or sulphur. Further compounds are formed by the degradation of trigonelline (pyridine), chlorogenic acid (vanillin), carotenoids (beta-Damascenone), fats (carbonyls) and sugar caramelisation (furaneol). The aroma impact compounds can be subdivided based on their functional groups. Within these, compounds containing sulphur play a major role.
Monitoring the evolution of coffee aroma during the roasting process using comprehensive GCxGC-qMS
Monitoring the formation of individual aroma compounds during the roasting process of coffee is a challenging task. The standard high resolution capillary Gas Chromatography system GC-2030 is not sufficient due to heavy coelution. By one-dimensional GC-MS chromatography mostly volatiles with high concentrations can be identified. Switching to bi-dimensional chromatography using a GCxGCMS approach based on GCMS-QP2020 NX the separation increases dramatically and therefore, the number of visible volatiles. This comprehensive GC-MS is a powerful technique that provides the two-dimensional chromatography data acquisition, resulting in a significantly improved resolution and sensitivity. Data processing is done via Chromsquare software (Chromaleont srl, Messina). For individual volatiles with very low concentrations, but high odor active values, like some sulfur compounds additionally the Sulfur Chemiluminescence Detection Gas Chromatograph System Nexis™ SCD-2030 was used.
High Sensitivity Analysis of Coffee Aroma Components Using the SPME Arrow
Gas chromatograph mass spectrometers (GC-MS) capable of excellent qualitative measurements are used in the analysis of aroma components in foods and beverages. The convenient sampling methods of SPME (solid-phase microextraction) and HS (headspace extraction) are increasingly used for sample introduction. However, sample introduction methods such as these can suffer from insufficient sensitivity when analyzing some aroma components. The SPME Arrow method was developed as a new sample introduction option for the AOC-6000 Multifunctional Autosampler to address this shortcoming. The larger sorption phase volume compared to conventional SPME fibers allows the SPME Arrow to achieve high enrichment of volatile components and serve as a solution for applications where sensitivity was previously lacking.