Espresso coffee (EC) by POD: Study of thermal profile during extraction process and influence of water temperature on chemical–physical and sensorial properties

In this work the thermal profiles of five coffee pods (pure Arabica, pure Robusta, and Arabica Robusta
blends: A20R80, A80R20, and A40R60) at 90, 100 and 110 °C are reported. Moreover the chemical–physical
and sensorial properties of espresso coffee (EC) obtained from five different coffee pods were investigated.
The analysis of the thermal profiles highlighted that the extraction process can be considered as
an isothermal process because, after a starting phase, the recorded temperatures stayed around a mean
temperature (Tm). In addition the Tm recorded for each extraction temperature was significantly lower
than those set up by the controller. The chemical–physical parameters of EC samples increased proportionally
with extraction temperature highlighting that the effectiveness of extraction process scales up
with percolation temperature. The solid and caffeine contents of the EC samples extracted at 110 °C
are related to an over extraction process. Principal Component Analysis (PCA) was applied to identify
relationships and differences among EC samples. Pure Arabica and A80R20 EC samples at 100 and
110 °C have shown sensorial attributes typical for a fine espresso coffee.