Phase Behaviour of Lactose as Affected by Presence of Lactic Acid and Minerals

Owing to growing markets for Greek yoghurts and soft cheeses, dairy industry generates huge quantity of acid whey creating a significant environmental problem globally. This by-product cannot be simply disposed of due to its toxicity during decomposition, robbing oxygen from rivers and streams creating health and environmental concerns. Currently, there is no solution to acid whey waste, but it seems the behaviour of lactose in presence of LA and Ca in acid whey restricts its further processability due to the failure of lactose to crystallize which thus remains in its amorphous form during concentration and further processing, including spray drying. Hence, the present study aims at fundamentally understand the concentration and crystallisation behaviour of lactose and its interactions with other constituents of acid whey especially LA and Ca. A model based study was thus implemented with varying concentrations of Ca (0.12, 0.072 or 0.035% w/w) and LA (0.05, 0.2, 0.4 or 1% w/w) in establishing behaviour of lactose during concentration up to 50% (w/w). Different concentrations of LA and Ca were selected to imitate the concentrations originally present in acid whey, nanofiltered retentates and sweet whey. Furthermore, the crystallization nature of freeze dried lactose in presence of LA and/or Ca were investigated. Differential scanning colorimetry (DSC) was used to determine the phase transitions while, fourier transform infrared spectroscopy (FTIR) was used to determine the structural changes and screens the molecular vibrations shown by various compounds