Quality by Design (QbD) considers both the critical product characteristics and the environmental variables to design an optimum packaging system. This study applied the QbD approach for packaging and shelf-life determination of Granola by i) determining the water vapour transmission rate (WVTR) of packaging films at different environmental conditions, ii) develop and validate a shelf-life model of packed granola breakfast product and iii) predict shelf-life of packed Granola. The WVTR of packaging films (BOPP and biodegradable films, i.e., NK, NM, N913) was measured according to a full factorial experimental design (3(2)), i.e., 10, 30, 40 degrees C; 32.5 +/- 0.5, 75.5 +/- 0.5, 92.5 +/- 3.5% RH, and a mathematical model was developed. Granola breakfast product was packed (using the mentioned materials and also a commercial packaging film-control), stored under accelerated conditions (38 degrees C and 90% RH) and assessed for moisture content (critical quality parameter). A shelf-life model was developed and validated for Granola describing the relationship of the food, packaging and environmental conditions, and shelf-life was inferred for normal storage conditions. The developed WVTR global model considering the dependency of temperature and relative humidity was found to fit the experimental data well (R-2 > 0.914). Granola moisture gain was the lowest in BOPP package followed by biodegradable N913 package. The shelf-life for Granola under accelerated conditions ranged from 2 to 13 days depending on the packaging film, and under normal storage conditions (20 degrees C and 75% RH) was 271, 269, 90, and 33 days for BOPP, N913, NK and NM packages, respectively. (C) 2012 Elsevier Ltd. All rights reserved.