Physical properties of cryogels obtained by ball-milled starch as novel βcarotene carrier

Aim: Nowadays, there is an increasing trend in developing tailor-made and personalized foods with enhanced health and bioactive delivery performances. Starch is a cheap, plant-origin and widely available biomolecule used in formulated foods, whose technological performances could be enhanced by technologies that induce molecular and/or state modifications. Ball milling is an emerging and “green” technology that could induce physical modifications of macromolecules. In this study cryogels (i.e. aerogels obtained by freeze-drying) have been obtained by using corn starch modified by ball milling, as innovative carrier systems and for -carotene controlled release purposes.  Method: Corn starch was physically modified by ball milling (speed: 350 rpm) for different times (from 3 to 30 min). Native (NS) and modified starches (MS) were characterized for their rheological properties upon heating conditions and used to prepare cryogel monoliths made of starch alone or in presence of -carotene (N-C, MS-C). 10%w/w starch dispersion were heated at 90 °C for 10 min, cooled down to 4°C, frozen and freeze dried. For both C-cryogels 0.6% of -carotene was added before freezing. Cryogels were analysed for porosity, microstructure, mechanical properties and water interaction. For C, load efficiency and other physical properties were additionally assessed.  Results: MS showed lower gelatinization temperature at increasing milling time. Hydrogels from MS milled for 15 and 30 min present lower storage modulus values compared to those from starch milled for shorter times and NS. A lower bulk density, a higher number of pores was observed in MS cryogels leading to a higher surface specific area. In presence of β-carotene, cryogels properties changed: a lower hardness was observed despite a denser microstructure and lower porosity was observed likely due to competitive action of the lipophilic bioactive. The C loading efficiency ranged between 22 and 45% for cryogels made of MS with no significant differences due to ball milling time applied. Conclusion: Ball milling modification could improve the starch performances in the development of cryogels intended for bioactive compounds delivery. However, C induced changes of the structural properties of the aerogels whose effects on the bioactive bioaccessibility and stability are under investigation.