FTIR-ATR Spectra of Pelagic Sargassum Specimens under Different Flash-Freeze Timing and Cryogenic Storage Conditions

About the data set origin The dataset comprises ATR-FTIR spectral CSV files of pelagic Sargassum specimens, including S. fluitans III (labeled "flu3" in the sample ID), S. natans I (labeled "nat1"), and S. natans VII (labeled "nat8"). The specimens were collected from three sites on the south Mexican Caribbean coast: Mahahual (labeled "Ma"), Xcalak (labeled "Xk"), and Xahuayxol (labeled "Xa"). The experimental design includes a treatment condition based on the timing of flash-freezing: the fresh group (labeled d00) and the lab group (labeled d01). The fresh group was flash-frozen on the shore and stored under cryogenic conditions, while the lab samples were flash-frozen upon arrival at the laboratory facilities. The sample IDs are listed in Table 1. About the Equipment and Data Acquisition All ATR-FTIR analyses were conducted using a Nicolet iS5 from Thermo Scientific (USA), equipped with an iD7 accessory and a ZnSe crystal plate. The Thermo Scientific OMNIC software was used for the analysis. Background noise was removed from all spectra. The spectral acquisition range spanned from 500 to 4000 cm⁻¹, with 32 scans per sample and a spectral resolution of 4 cm⁻¹, resulting in a data spacing of 0.482 cm⁻¹. Each sample was analyzed in triplicate. Table 1. Sample ID and size for the flash-freeze comparison dataset Site Morphotype Flash-freeze treatment Samples collected Samples read in triplicate Mahahual (Ma) S. fluitans III (flu3) Fresh (d00) 2 6 Lab (d01) 2 6 S. natans I (nat1) Fresh (d00) 2 6 Lab (d01) 2 6 S. natans VIII (nat8) Fresh (d00) 2 6 Lab (d01) 2 6 Xahuayxol (Xa) S. fluitans III (flu3) Fresh (d00) 1 3 Lab (d01) 2 6 S. natans I (nat1) Fresh (d00) 1 3 Lab (d01) 2 6 S. natans VIII (nat8) Fresh (d00) 1 3 Lab (d01) 2 6 Xcalak (Xk) S. fluitans III (flu3) Fresh (d00) 1 3 Lab (d01) 2 6 S. natans I (nat1) Fresh (d00) 1 3 Lab (d01) 2 6 S. natans VIII (nat8) Fresh (d00) 1 3 Lab (d01) 2 6 Total 30 90