Crystallization of amorphous lactose at high humidity studied by terahertz time domain spectroscopy

► Solid state crystallization of amorphous lactose was studied using THz-TDS. ► Crystallization kinetics could be studied both quantitatively and qualitatively with THz TDS. ► THz-TDS was shown to be very sensitive to the uptake of water by amorphous lactose. ► Peak broadening showed that THz-TDS is sensitive to crystallite size and growth. ► Changes in time-domain data were shown to be indicative of crystallization in the bulk material.