Effect of cooling rates and low crystallization temperatures on morphology of lactose crystals obtained from Ricotta cheese whey
Department of Food Science and Technology, Estonian University of Life Sciences, Kreutzwaldi 56/5, EE51014 Tartu, Estonia; *Correspondence: anna.pisponen@emu.ee
Abstract:
In the traditional process of lactose production from cheese whey crystallization temperature is reached by slow cooling. Lactose morphology obtained in this way has been well investigated. The objective of this work was to study morphological parameters of lactose crystals during crystallization at low temperatures, using rapid and extra rapid cooling. Ricotta whey was chosen for analysis because this raw material has been poorly investigated as a source of lactose production. Three temperatures (2, 6 and 12°C) were used for crystallization of lactose. Rapid (0.5°C min-1) and extra rapid cooling (3°C min-1) rates were used to achieve these temperatures. Dimensions of crystals were examined with optical stereo-, and scanning electron microscopes. Pure lactose solution was used as a reference during the study. The results of the study showed the impact of some Ricotta whey components on the crystals morphology and size. These components reduce crystals size, and linked with low crystallization temperature, modify the shape of crystals faces. Extra rapid cooling of Ricotta whey contributes to the growth of needle-like crystals more than the rapid one. In a pure lactose solution no needle-shaped crystals were observed.
Key words:
cooling rate., crystallization, lactose, Ricotta cheese whey