Water usability as a descriptive parameter of thermodynamic properties and water mobility in food solids

• Published in: NPJ science of food Vol. 7; no. 1; p. 30
• Main Authors: Cui, Tingting, Wu, Xukai, Mou, Tian, Fan, Fanghui
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.06.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 631/45/56; 639/301/54; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Food; Food Microbiology; Food preservation; Food Science; Glucose; Metabolism; Metabolites; Microorganisms; Mobility; Moisture effects; Nutrition; Proteins; Sorption; Thermodynamic properties; Thermodynamics; Usability; Yeasts
• ISSN: 2396-8370; 2396-8370
• DOI: 10.1038/s41538-023-00207-0

A classic problem in preservation is the microbes can grow in low-moisture foods. In this paper, the water sorption, and thermodynamic properties of glucose/WPI solid matrices were measured, while their molecular mobility was analyzed and associated with the microbial growth of D. Hansenii at various a w and 30 °C. Although the sorption isotherms, T g , and relaxation processes of studied matrices were affected by a w and WPI, the microbial growth showed highly dependent on water mobility rather than a w . Hence, we introduced water usability ( U w ), derived from the mobility difference between system-involved water and liquid pure water explicating from the classical thermodynamic viewpoint, to describe the dynamic changes of water mobility in glucose/WPI matrices. Despite to a w , the yeast growth rate was enhanced at high U w matrices concomitantly with a rapid cell doubling time. Therefore, the proposed U w provides a better understanding of the water relationships of microorganisms in food preservation.