Water Activity−Temperature State Diagram of Amorphous Lactose

• Published in: Journal of agricultural and food chemistry 2005-11, Vol.53 (23), p.9182-9185
• Main Authors: Thomsen, Marianne K, Jespersen, Lone, Sjøstrøm, Kirsten, Risbo, Jens, Skibsted, Leif H
• Format: Article
• Language: English
• Subjects: amorphous lactose; Biological and medical sciences; Calorimetry, Differential Scanning; Chemical Phenomena; Chemistry, Physical; differential scanning calorimetry; dried milk; Food industries; food storage; Fundamental and applied biological sciences. Psychology; glass transition temperature; lactose; Lactose - chemistry; Milk and cheese industries. Ice creams; storage quality; Temperature; Thermodynamics; Water - chemistry; water activity
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0508394

Development in the glass transition temperature, T g, to reach a stabilized value for amorphous lactose stored at 5, 25, and 38 °C at different water activities varying from a w = 0.21 to 0.59 was followed by differential scanning calorimetry. Combinations of stabilized T g and water activity were used for interpolation of the value of water activity, where T g was equal to the storage temperature. These values of water activity were used to construct a state diagram in the (a w,T)-plane for lactose in the amorphous state from which critical combinations of water activity and storage temperature may be obtained for optimization of storage conditions of lactose-based dry products. Keywords: Lactose; glass transition temperature; T g; water activity; DSC; milk powder