Utilisation of agricultural residues for antioxidant exopolysaccharide production by spp.

This study tested the antioxidant activities of exopolysaccharides (EPSs) produced by eight spp. from Thai milk kefir utilising four agricultural by-products in Thailand; copra meal, mangosteen peel, sorghum, and para rubber sawdust as carbon sources. Sorghum showed the highest starch and sugar content of 73.33% while copra meal showed the lowest (13.08%). PS21 produced the highest dry weight EPS, followed by KW1 and PS22 from four substrates. PS21 generated the most EPS with sorghum (0.75 ± 0.09 g DW/100 mL culture), followed by mangosteen peel (0.61 ± 0.07 g). EPS from KW1 using copra meal displayed the highest DPPH radical scavenging activity of 33.39 ± 1.34% and EPS from the same bacteria using sorghum displayed the highest hydroxyl radical scavenging activity of 49.78 ± 0.86%. This approach demonstrated a bio-circular green economy paradigm in converting agricultural biowastes into valuable EPS biomaterials with potential applications.