Effect of ball milling as a green and sustainable technique on the techno-functionality of tapioca starch

Consumers are increasingly demanding transparency and sustainability in their food choices, reflected in the rising need for clean and green labelling. This trend is driving innovation in starch modification, particularly towards processes that enhance functionality and health benefits while minimizing environmental impact and prioritizing consumer safety. However, native starch possesses limitations that hinder its full potential in various applications. To overcome these limitations, various modification techniques, including chemical, enzymatic, and physical methods, have been employed. In light of the growing consumer preference for "clean label" products, sustainable and innovative technologies like ball milling (BM) are gaining significant traction. This study aimed to elucidate the changes in the technological functionality of tapioca starch modified by BM for varying duration (5, 15, and 30 minutes) at a constant speed (350 rpm). The properties studied were swelling power (SP), cold water solubility (CWS), water and oil holding capacity (WHC & OHC), particle size distribution, granular morphology, damaged starch (DS), rheological, and thermal analysis. The functionalities of BM treated samples were dramatically increased (P> 0.05) with increasing BM time. Notably, significant differences were observed in DS, WHC and OHC (P>0.05). CWS exhibited a sharp increase at 30 minutes of milling. In contrast, SP remained relatively unchanged (p < 0.05) after 5-minute treatment (P< 0.05). Microscopic analysis using confocal laser scanning microscopy revealed smooth surface with well-defined, alternating growth rings and pronounced shape in the native starch granules. Conversely, ball milling treatment (BMT) yielded irregular granular surface and distorted granules with disappearance of alternate growth rings. Increasing milling time resulted in particle size growth due to formation of agglomerate. Compared to native starch, BMT samples exhibited a lower gelatinization enthalpy and temperature. Furthermore, rheological assessment revealed a weaker gel structure in BMT starches, characterized by lower storage modulus (G') and higher loss modulus (G'') and tan δ shows the modification of starch-generated elastic gel. These findings indicate that Ball milling (BM) has the potential to obtain modified tapioca starch as a functional ingredient to be used in food applications.