Effects of process variables on the denaturation of whey proteins during spray drying

The effects of varying feed concentration (20-40% w/v) and outlet temperature (60 to 120 degrees C) on whey protein denaturation (determined by DSC) and solubility (at pH 4.6) have been investigated in a pilot-scale co-current spray dryer. The study confirms that low outlet gas temperatures (60 and 80 degrees C) produce the lowest amount of denaturation and solubility loss, with almost complete denaturation observed at 120 degrees C along with a less dramatic reduction in solubility. Slightly more denaturation and loss of solubility was found with a 40% feed concentration. It is hypothesized that crust formation, resulting in high particle temperatures while still maintaining a wet core, is likely to lead to high levels of denaturation.