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A simple method to determine the water activity of ethanol-containing samples
1Department of Applied Microbial Technology, Kumamoto Institute of Technology, Kumamoto City, Japan.
Biotechnology and Bioengineering
|April 1, 1999
Summary
A new method accurately measures water activity (aw) in ethanol-containing samples using alcohol-resistant sensors and correction equations. This overcomes limitations of previous techniques for foods, drinks, and biological samples.
Area of Science:
- Food Science
- Microbiology
- Analytical Chemistry
Background:
- Water activity (aw) is crucial for microbial growth, food stability, and shelf-life.
- Ethanol in samples interferes with standard humidity sensor measurements.
- Previous methods for ethanol-containing samples were indirect and problematic.
Purpose of the Study:
- To develop a rapid and accurate method for determining water activity (aw) in samples containing ethanol.
- To overcome the limitations of existing techniques for measuring aw in the presence of alcohol.
Main Methods:
- Utilized a newly developed, alcohol-resistant humidity sensor with an integrated alcohol filter.
- Employed linear equations derived from standard ethanol-water mixtures and Norrish's equation for sensor data correction.
- Performed measurements at ambient temperatures.
Main Results:
- Successfully minimized disruption of sensor measurements caused by ethanol.
- Achieved rapid and accurate determination of water activity in ethanol-containing samples.
- Established a novel application of electronic sensors for aw measurement in such matrices.
Conclusions:
- The developed method provides a significant advancement for accurately measuring water activity in diverse ethanol-containing materials.
- This technique offers a more efficient and reliable alternative to previous indirect methods.
- Represents the first use of electronic sensors for determining the water activity of ethanol-spiked samples.