Multi-trait dataset on the postharvest quality, carrageenan, heavy-metal, and bioactive profiles of dried tropical Kappaphycus seaweed across four cultivation locations and harvest-age classes in South Sulawesi, Indonesia.

This data article presents numerical and visual datasets for dried commercial Kappaphycus seaweed lots collected during March-June 2022 from four production locations in South Sulawesi, Indonesia: Bulukumba, Takalar, Pangkep, and Palopo. It provides a preliminary, period-specific reference for lots classified into <35- and >35-day harvest-age classes. The records integrate observations from the same sampled lots, facilitating comparisons across measured quality attributes without implying regional or causal effects. The datasets include sample codes, production location, collection month, harvest age, visual appearance, cultivation information, physicochemical quality indicators, heavy-metal content, carrageenan yield and viscosity, total phenolic content, and DPPH radical scavenging activity. Relative to the initial dried-seaweed weight, moisture, ash, acid-insoluble ash, salt, and clean anhydrous weed ranged from 21.27-30.27%, 30.76-39.88%, 0.13-1.93%, 9.20-19.94%, and 63.22-76.55%, respectively. Mercury, cadmium, and lead concentrations were 0.040-1.760, 0.280-0.740, and 0.140-0.930 mg/kg of dried seaweed, respectively, while tin was not detected. Carrageenan yield varied across locations and harvest-age classes, ranging from 15.13% in Bulukumba (>35 days) to 27.00% in Pangkep (<35 days), while viscosity ranged from 27.82 to 38.46 cP. Total phenolic content ranged from 63.00 ppm GAE in Takalar (>35 days) to 192.00 ppm GAE in Pangkep (<35 days), whereas DPPH inhibition ranged from 12.03% in Pangkep (<35 days) to 43.95% in Bulukumba (>35 days). These data support preliminary comparisons of raw-material quality, carrageenan-processing assessment, heavy-metal monitoring, tropical-seaweed database development, and calibration of rapid quality-screening tools.