Interfacial properties of coffee-based beverages

The coffee brewing technique enhances several surface phenomena such as foam and emulsion formation and stabilisation. Recently the authors have been investigated the possibility to study the different contribution of the components of commercially available coffees well known as arabica and robusta. In the present work, dynamic experimental techniques such as maximum bubble pressure and contact angle have been used to characterise the air-coffee beverage interface at two different temperatures (20 degrees C and 37 degrees C). Different coffee-based beverage have been investigated ranging from espresso to soluble coffee. Beverage samples at different brewing times and methods have been prepared following standard procedures by using commercially relevant varieties and products. The role of the chemical components on tensiometric behaviour of the beverage is discussed. This behaviour is definitely related to the good wetting properties of the beverage on oral mucosa. (C) 2006 Elsevier Ltd. All rights reserved.