Antioxidant activity and combination characteristics of filtrates and sargassum polycystum seaweed salt residue

Sargassum polycystum is a low-sodium salt raw material that meets the dietary salt criteria, i.e., low Na: K ratio and NaCl content < 60%. This study aims to produce seaweed salt with high yield, dietary fiber content, and antioxidant activity according to the quality standard of dietary salt through a combination of the filtrate and salt extraction residue. The results showed that the produced S. polycystum brown seaweed salt had a mineral Na 96.97 mg/g and mineral K 247.59 mg/g. Na: K ratio of 0.39, NaCl content of 49.05%, and heavy metal residue below the Indonesian National Standard maximum standard for dietary salt. The levels of dietary fiber produced in salt samples 1:1, 1:2, and 2:1 was 34.41%, 40.16%, and 23.83%, respectively, and the iodine content (KIO3) of the control salt was 125.95 mg/kg. The antioxidant activity of seaweed salt 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) on salt K (seaweed salt without residue), residue, S1 (1:1), S2 (1:2), and S3 (2:1) was 26.41 ppm, 59.06 ppm, 12.29 ppm, 67.30 ppm, and 87.50 ppm. Meanwhile, the antioxidant capacity of seaweed salt Cupric Reducing Antioxidant Capacity (CUPRAC) on K salt, residue, S1, S2, and S3 were 12.36, 19, 7.86, 8.52 and 12.27 mu mol ascorbic acid/g extract, respectively. Therefore, it was concluded that increasing the yield and dietary fiber content in the seaweed salt production process is achievable by adding residues.