isotherm-fit

Automated fitting of moisture sorption isotherm models (GAB, BET, Peleg) to experimental water activity data, with objective model selection and food-stability assessment via the monolayer moisture content (m₀).

Problem

Moisture sorption isotherms — the relationship between equilibrium moisture content and water activity (a_w) — underpin drying process design, storage stability prediction, and shelf-life estimation in food science. Researchers typically measure a handful of (a_w, moisture) points with the saturated salt solution method and then fit models (GAB, BET, Oswin, Henderson, Peleg) by hand in spreadsheets or proprietary software — a slow, inconsistent process. isotherm-fit automates model fitting, objective model selection (AIC), and stability-relevant parameter extraction, producing a publication-ready report.

Installation

pip install isotherm-fit

Or from source:

git clone https://github.com/karenkhachatryan-lab/isotherm-fit.git
cd isotherm-fit
pip install -e ".[dev]"

Usage

Input CSV with columns aw, moisture (g water / 100 g dry solid or kg/kg), and optionally moisture_std:

aw,moisture,moisture_std
0.113,3.21,0.08
0.225,4.85,0.10
0.328,6.02,0.09
...

Fit models and generate a report:

isotherm-fit fit data.csv --output report

This produces:

• report.pdf — isotherm plot with all fitted model curves, parameter/metrics table, stability zone, residuals plot for the best model,
• report.json — fitted parameters, metrics (R², RMSE, AIC), and m₀ for downstream use (e.g. drying simulations).

Print citation information:

isotherm-fit cite

Desktop GUI (optional)

pip install "isotherm-fit[gui]"
isotherm-fit gui

Opens a desktop window (CustomTkinter) to load a CSV, pick models, view the report plot and metrics live, and save the PDF/PNG/JSON outputs — no command-line arguments needed.

For users without Python, a prebuilt standalone Windows GUI is attached as a .zip to each GitHub Release — download, extract, and run isotherm-fit-gui.exe, no installation needed. To build it yourself instead, see packaging/build_exe.ps1 (PyInstaller) in docs/installation.md.

Project status

Early development (v0.2.0) — MVP scope: GAB, BET, Peleg models; CSV loader; AIC-based model selection; PDF/PNG + JSON report generation; CLI via Typer; optional CustomTkinter desktop GUI. See CHANGELOG once released.

Citing this software

If you use isotherm-fit in your research, please cite it — see CITATION.cff or run isotherm-fit cite for the formatted citation and BibTeX entry. DOI: 10.5281/zenodo.21710137.

License

MIT — see LICENSE.