Understanding the properties of chocolate using laser diffraction particle size distribution analysis

Abstract: The particle size and size distribution of the cocoa solids and other ingredients present in chocolate is important in defining the mouth feel of the chocolate and in controlling manufacturing costs. Too coarse a particle size many yield an unpleasant, gritty mouth feel. Conversely, over-grinding to too fine a particle size may increase production costs as more cocoa butter must then be added to produce the desired rheological properties.

Introduction

Chocolate is without doubt one of the world's best-loved foodstuffs. Fry and Sons produced the first plain chocolate bar in 1847, with the first milk chocolate product being launched by Nestle in 1870's [1]. Initially product consistency was poor. However, the introduction of the chocolate kneading process, referred to as conching, by Lindt in 1879 yielded improved flavor and texture [1]. Since then the world's desire for chocolate products has expanded rapidly such that in 2009 chocolate consumption worldwide reached over 7.2 million metric tons [2].

For the consumer, taste is the overriding factor in selecting a chocolate product; for the producer, consistent high quality using optimized, economical and efficient production systems is vital. While there are many parameters to be considered in the production of chocolate, a major factor at all stages is the solid ingredient particle size distribution as this has a significant effect both on the final product and on the cost and efficiency of the production process itself.

This application note examines why particle size distribution analysis is important in the manufacture of chocolate. Examples of the characterization of different chocolate products using laser diffraction particle sizing are also described.