Developing new technological functionalities of starch by ball milling for innovative food structures

Starch is generally used in food formulations as ingredient for thickening, gelling properties or as fat mimicker. To widen its applicability, rather limited in its native state, chemical modifications that enhance the water solubility and technological functionalities of the starch are performed, despite the use in foods of the modified molecules require them to be listed as additive. Green and sustainable trends in food technology are boosting enzymatic or physical processes to obtain modified biopolymers aligned with “clean label” strategies. Ball milling is a physical technology that recent investigations are showing some potential for starch modification and improvement of its technological properties. This study aims to evaluate the effect of ball milling time on starch of different botanical source on their technological functionalities and structuring ability. Corn and potato starch were treated by planetary ball milling at constant speed for different times up to 30 min. Swelling ability, cold water solubility and water holding capacity were determined on native (N) and modified (MS) samples. N and MS hydrogels were obtained by thermal treatments and evaluated for their rheological properties. N and MS Starch cryogel monoliths were produced by freeze-drying of heat-treated 10% w/w starch dispersions. Microstructure, through scanning electronic microscopy, was determined to highlight differences in structuring ability. MS samples showed a significant increase of the cold-water solubility and water holding capacity. Hydrogels obtained from modified starches showed significantly lower storage modulus, positively correlated with the treatment time, reflecting a weaker gel structure. Potato starch hydrogels showed by a significant lower storage modulus compared to corn starch, suggesting higher sensitivity towards ball milling treatment. Cryogels of MS samples differed from native ones in terms of number and size pores. Results unravel the potential applicability of ball milling as physical technology to produce of modified starch and innovative food structures.