title: Common-ion effects on the deliquescence lowering of crystalline ingredient blends.
abstract: Deliquescence points (RH0, RH0mix) of ionic crystalline food ingredients and blends thereof were determined using water activity and moisture sorption techniques. Measured RH0mix values of ingredient blends with and without a common ion were compared to Ross equation predictions of deliquescence lowering. In binary blends with no common ion, measured RH0mix values ranged from 5% RH lower to 6% RH higher than predicted; however, when a common ion was present, the measured RH0mix was consistently 6-8% RH higher than predicted. In tertiary blends with a common ion, RH0mix values were 15-18% RH higher than predicted. The higher RH0mix in blends with a common ion is caused by counterion dissociation competition from the common ion. At equilibrium, these solutions will have fewer solutes and a greater vapor pressure than assumed by the Ross equation. A modified Ross equation was developed to compensate for the common-ion effect and improve RH0mix predictions.
authors.affiliation: Department of Food Science, Purdue University, 745 Agriculture Mall Drive, W. Lafayette, IN 47907, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Allan
authors.affiliation: Department of Industrial and Physical Pharmacy, Purdue University, 575 Stadium Mall Drive, W. Lafayette, IN 47907, USA.
authors.forename: Lynne S
authors.initials: LS
authors.lastname: Taylor
authors.affiliation: Department of Food Science, Purdue University, 745 Agriculture Mall Drive, W. Lafayette, IN 47907, USA. Electronic address: mauer@purdue.edu.
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Mauer
mesh_terms: D003460:Crystallization; D005504:Food Analysis; D006813:Humidity; D044367:Phase Transition; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water
keywords: Common-ion effect; Deliquescence; Deliquescence lowering; Ross equation