Prediction of the shelf life of porang chips and flour using a mathematical model of water mass transfer

Abstract Moisture plays a critical role in the quality degradation of porang chips and flour during storage, making shelf-life prediction essential for maintaining product quality. This study aimed to develop and validate a mathematical water mass transfer model to predict the shelf life of porang chips and flour under varying relative humidity (RH) conditions (50, 70, and 90%) at a constant temperature of 25 °C. Shelf-life testing was conducted using the Accelerated Shelf-Life Testing (ASLT) method over 90 days. Moisture content was monitored periodically and analyzed using the developed model based on moisture balance between storage air and solid material. The model parameters, P and Q, were optimized through numerical analysis. The model showed high predictive accuracy with R2 values exceeding 0.99 for both product forms. P and Q exhibited strong polynomial relationships with RH, enabling accurate moisture uptake and shelf life prediction across different storage conditions. Experimentally, porang chips absorbed moisture faster and in greater amounts than porang flour due to their more porous structure, lower particle density, and higher starch content. After 90 days, porang chips declined from Grade I to Grade II, while porang flour dropped from Top Grade to First Grade. Model predictions showed that chips with 15% moisture content (Grade III) had a shelf life of 348, 153, and 99 days at RH levels of 50, 70, and 90%, respectively. For flour with 12% moisture (second grade), shelf life was 537, 274, and 202 days under the same conditions. The model’s simplicity, requiring only basic inputs such as initial and target moisture content and empirical P and Q values, makes it practical for predicting the shelf life of porang and other dry, hygroscopic food products.