Effect of the particle size of spray-dried milk powder on some properties of chocolate

Abstract

Spray-dried milk powders have a median particle size of 30-80 µm. Roller-dried powder particles, which are larger (about 150 µm), are preferred for chocolate making. Spray-drying varia- bles were therefore studied to produce larger powder particles for chocolate. The particle size of the spray-dried powders increased with increasing size of the spray nozzle orifice used. The free-fat content, vacuole volume and insolubility index of the powders increased at the above normal air out- let temperatures used to dry the large powder particles. Vacuole volume and moisture contents typi- cal for spray-dried powders were obtainable at air outlet temperatures up to 90 °C. The particle size of the chocolate mix after refining and the Casson yield value of the chocolate after conching rea- ched minimum values using spray-dried powders with median particle size values of 132-162 µm. These minimum values in the chocolates were also correlated with higher contents of free-fat and lower vacuole volumes in the powders. The spray-dried powders produced good quality British- style chocolates, where the particle size after refining is conventionally <26 µm, but not continental chocolates, where the particle size should be <20 µm.