From Granules to Porous Gels: Exploring the physical, structural and technological properties of ball-milled starches from different origins

Starch, a widely used biopolymer in the food industry, has limited applications in its native state. Technologies based on chemical, enzymatic and physical principles have been developed to modify starches end enhance food applications. Ball milling (BM), a mechanical technology, induces structural modifications and technological functionality of food biomolecules. Thus, the effect of BM treatment time on the structural properties and techno-functional properties of starches from different botanical sources was investigated; their usage for aerogels and cryogels as innovative delivery systems was investigated. Native starches (corn-CS), high amylose corn-HACS), potato-PS), tapioca-TS) and wheat- WS) were ball-milled for 5, 10, 15, 30 and 45 min at a constant speed (350 rpm). BM- starches were characterized for particle size distribution, morphological thermal and technological properties (water holding capacity-WHC, swelling power-SP, and cold-water solubility-CWS). Hydrogels were thermoset from native and BM starches and the evaluation of their rheological properties was performed. Aerogels and cryogels obtained via supercritical C0 2 and freeze drying respectively, were characterised for surface area, pore diameter, pore volume, density, porosity, and WHC. BM starches showed lower gelatinization temperature and enthalpy than native starches. Techno-functional properties correlated significantly with treatment time (p < 0.05). BM-TS showed a three-fold SP increase, while BM-PS a notable rise in CWS (p < 0.05). BM-TS-30 min enhanced WHC. Prolonged milling caused aggregate formation and weakened gel structure. All aerogels were mesoporous (≤ 25.4 nm), while cryogels were macroporous (≤ 200 µm). HACS aerogels demonstrated high textural properties, enhancing porosity and reducing bulk density compared to the other starches. BM-HACS-10 min showed the highest surface area (237 m²/g) while BM-PS a reduced surface area and porosity but increased bulk density over BM time. BM cryogels had twice WHC of aerogels. In conclusion, BM is an interesting technology applicable to modify native starches and their gel properties, enhancing their potential applications in food and non-food sectors. Keywords: Ball milling, Starches, Structural, Techno-functional, Textural, Thermal, Rheology properties. 1. Cai, M., Shen, C., Li, Y., Xiong, S., & Li, F. (2023). Effects of particle size on quality characteristics of stone‐milled whole wheat flour. Journal of the Science of Food and Agriculture, 103(5), 2483-2491 2. de Oliveira Barros, M., Mattos, A. L. A., de Almeida, J. S., de Freitas Rosa, M., & de Brito, E. S. (2023). Effect of Ball-Milling on Starch Crystalline Structure, Gelatinization Temperature, and Rheological Properties: Towards Enhanced Utilization in Thermosensitive Systems. Foods, 12(15), 2924 3. Hao, Z., Xu, H., Yu, Y., Gu, Z., Wang, Y., Li, C., ... & Yu, Z. (2024). Insights into ball milling treatment promotes the formation of starch-lipid complexes and the relation between multi-scale structure and in vitro digestibility based on intermolecular interactions. Food Hydrocolloids, 146, 109277.