Development, optimization and microbial stability of innovative gluten-free cereal bars

Gluten-free products are frequently produced from unflavored formulas, resulting in poor quality. Individuals with celiac disease may require dietary supplementation with nutritional and bioactive ingredients to rectify deficits and enhance the quality of final products. This study aimed to develop and optimize gluten-free cereal bars using wild seeds (pumpkin, Aleppo pine, and milk thistle seeds), puffed rice, and binders (pomegranate molasses and sunflower butter), and apply cold plasma treatment to assess the effect on the microbial stability.

A three-simplex centroid mixture design was employed, integrating sensory evaluation and texture parameters. The optimal cereal bars were selected and further evaluated by their physico-chemical and antioxidant properties. Cold plasma treatment was applied to optimized bars, and microbial tests were conducted.

The main results indicated that the combination of 44.8485 g of seeds, 20.1515 g of puffed rice, and 35 g of binder was optimal (optimal 1), followed by the second optimal combination of 20.2049 g of puffed rice, 42.1433 g of seeds, and 37.6518 g of binder (optimal 2). Both cereal bars showed high protein (18.55 and 17.55 g/100 g), fat (25.7 and 30.55 g/100 g), fiber (29.2 and 17.9 g/100 g), and caloric values (422.3 and 416.7 kcal/100 g), respectively. Furthermore, both cereal bars demonstrated high antioxidant activities, with total polyphenol values exceeding 11 mg/g d.w. Texture characterization revealed that both cereal bars exhibited high values of hardness and chewiness with a high overall acceptance rating (7.24 and 7.21, respectively). Cold plasma at 40 W for 20 min reduced microbial loads (over 70%), with Optimal 2 showing the lowest counts (1.84 log CFU/g). During 14 days of storage at room temperature, microbial levels stayed stable and safe, while yeast and mold remained undetectable.

The developed products in this study can be recommended as nutritious, gluten-free, high-energy, and high-fiber bars, and cold plasma proved effective for safety and shelf-life extension.