Scaling Up Micronization Techniques for Enhanced Bioactive Recovery from Rucola Leaves: from High-pressure Homogenization to Disc Mill

Micronization techniques like High pressure homogenization (HPH) and Disc milling (DM) are mechanical, high-shear processes used to reduce food particle size to the micron scale. These cell disruption technologies are widely used to complement green extraction processes for bioactive compound extraction, reducing the need for high temperature or organic solvents. However, while effective in disrupting cell structures and enhancing mass transfer, some techniques face scalability limitations. Identifying scalable alternatives is essential for reproducing small-scale results in industrial applications. This study investigates DM as a viable technique for scaling up HPH and promoting the extraction in water of bioactive molecules from rucola. High shear mixing (HSM) was utilized as a benchmark. Rucola was treated with HPH and DM in distilled water at ratios of 1:10 and 1:3 (w/v), respectively. The number of passes varied from 5 to 15 for HPH and 1 to 5 for DM. Extraction efficiency was evaluated using ferric-reducing antioxidant power (FRAP) for the extracts collected in the supernatant, along with total phenolic compounds (TPC) and total flavonoid compounds (TFC) analyses. Particle size distribution and microscopy assessed the extent of cellular disruption. Results indicate that DM up to five passes achieved significant particle size reduction, comparable to HPH, with d(0.1), d(0.5), and d(0.9) reduced to 70.3 µm, 334.2 µm, and 825.7 µm, respectively, suggesting complete cell disruption. Consequently, TPC, TFC, and FRAP values significantly increased compared to HSM- and HPH-treated samples. Moreover, DM's lower operational temperature and milder mechanical forces likely contributed to enhanced compound preservation and higher antioxidant activity. Overall, DM proves to be an effective technique for HPH scaling up, improving bioactive compound extraction and antioxidant activity in rucola, and offering a sustainable approach to agrifood residue valorization.