Evaluation of the Shelf Life of Multigrain Puffed Foods Bound with Liquid Egg or Pullulan

To evaluate the stability of multigrain puffed foods, samples bound with liquid egg or pullulan were stored at 25 °C under eight relative humidity (RH) conditions (6-94%). For shelf-life assessment, the samples were additionally stored at 25 °C and 57.6% RH in a constant-temperature chamber for 30 days. Their rupture properties, moisture sorption behavior, and starch retrogradation were examined. Pullulan-bound samples maintained their apparent elastic modulus throughout the one-month storage period. In contrast, liquid egg-bound samples exhibited a marked decrease in modulus by day 2, followed by a gradual recovery; by day 7, both sample types showed comparable values. The glass transition temperature (Tg) increased as moisture content decreased. At approximately 4% moisture content on the baking day, the glass-to-rubber transition occurred at 50-60 °C. X-ray diffraction analysis confirmed that no starch retrogradation occurred after one month of storage. Overall, these results demonstrate that multigrain puffed foods-particularly those bound with pullulan-retain their textural and structural stability during one month of storage. These findings provide a scientific basis for developing nutritionally balanced, allergen-conscious, and shelf-stable multigrain puffed products, supporting their potential use as meal-replacement-type emergency foods.