Abstract

Consumers value foam as a key quality feature of coffee and coffee-based beverages. However, perceptions of foam quality vary from country to country and even from consumer to consumer. This study provided measurable parameters which can be used to tailor products to consumers’ foam preferences. The analytical techniques described in this study enable the foam of coffee and coffee-milk beverages to be visualized and quantified in terms of volume and structure. It is intended to serve as a basis to quantify consumers’ subjective expectations of different coffee-based products, in terms of appearance. The aim of the present study was to develop an analytical methodology for the objective assessment of customer-specific requirements. For this purpose, the parameters foamability and foam stability were assessed by means of image analysis, while changes in structure were measured with a Dynamic Foam Analyzer. All measurements were carried out in triplicate with an overall RSD of ≥7%. The proposed procedure allowed normally subjective quality features of a variety of foams in different coffee species and milk types to be objectively characterized. This knowledge will enable further investigation into tailoring the scientifically assessed foam properties to subjective sensory characteristics perceived by the consumer, such as smoothness, fineness, body, thus helping to better satisfy rapidly evolving coffee consumer trends.

Key words: Foamability, foam stability, foam structure, bubble size distribution, coffee crema, coffee-based beverages.