Alcohol Stability of Milk from the Perspective of X-Ray Diffractometry

摘要

The stability of alcohol solutions is an issue that is still important for the dairy industry. The crystallographic profile of milk that is stable or unstable to alcohol has never previously been evaluated by X-ray diffractometry. In order to provide more information about aspects of crystallinity, we investigated the crystallographic profile of milk that was stable or unstable in 72 % (v/v) alcohol solution. The samples were lyophilized and analyzed by diffractometer and scanning electron microscopy. The unstable milk samples showed higher relative crystallinity and more intense peaks in the X-ray spectra. This suggested that the crystallographic structure of the milk that was unstable to alcohol may have been different to the stable milk. The intensity of the peaks could be explained by the quantity of alpha-lactose crystals, which were present in a greater ratio in the unstable milk, while the stable milk presented other lactose-crystal forms, such as beta-lactose or crystals of alpha and b-lactose in different molar ratios. The findings of this study reinforce the fact that the alcohol stability test is not always a reliable indicator in predicting the microbiological origin of acidity and thermal stability. In terms of food and pharmaceutical technology, the results of this study provide another variable that is useful to control the alcohol stability of any product containing ethanol and lactose, i.e. the ratio between the polymorphisms of lactose.