Measurement of sticky point temperature of coffee powder with a rheometer

Abstract

Sticky point temperature (Ts) is a parameter that quantifies stickiness of food and biological powders. It is traditionally measured using glass instruments. In this study we developed a new methodology to measure sticky point temperature using a rheometer, and we successfully used it to determined Ts for coffee powder samples. The behavior of coffee Ts as a function of moisture content (%, db (i.e., dry basis)) was observed to be non-linear, but after 16% (db) moisture content, there were no changes in Ts with further increases in moisture content. An exponential prediction model for Ts = f(moisture content) was achieved with an R2 value greater than 0.93; a power law regression model also fitted well, with an R² value of 0.97. Rheometry was shown to be a viable and convenient means to determine Ts for various coffee powders.