An innovative approach to efficiently produce starch nanoparticles: Leveraging the full potential of ball milling technology

The compact outer shell of starch granules impedes the efficient production of starch nanoparticles. Grinding in a ball mill can break down this shell, enabling hydrolysis that yields higher nanostarch production under milder conditions than previously reported. This research examines how controlled grinding in a planetary ball mill over a wide range of milling times (5 minutes to 24 hours) affects the morphology of both native and waxy starches, and explores neutral and acid-catalyzed hydrolysis for efficient nanostarch production. As grinding time increases, the particle size gradually decreases and the particles assume a yellowish hue. Even short grinding durations (5-30 minutes) can significantly deteriorate crystallinity, reducing it to approximately 0%, while simultaneously increasing water sorption capacity to 10.97%. Controlled grinding facilitates the creation of both crystalline and amorphous nanoparticles. To produce starch nanocrystals (SNCs), we combined short-term grinding (15-60 minutes) with long-term acid hydrolysis (4-20 hours) of waxy starch. Specifically, after 15 minutes of grinding and 16 hours of sulfuric acid hydrolysis, we successfully produced SNCs in the characteristic parallelepiped shape. We achieved a 42.5% yield with shorter acid hydrolysis times, surpassing previous reports. The anisotropic phase separation in starch suspensions is a good indicator of SNCs at high concentrations.