Tskgel g2500pwxl

The molecular weight (Mw) of WEAX was determined with a Tosoh EcoSEC HLC-8320GPC (Tosoh, Tokyo, Japan) using EcoSEC software. WEAX sample aliquots were solubilized in 0.1 M NaNO₃ and filtered with a 0.45 μm nylon filter. The solutions (200 μL) obtained were separated on TSKgel GMPWxl and TSKgel G2500PWxl (7.8 mm ID × 300 mm, Tosoh, Tokyo, Japan) columns by isocratic elution with 0.1 M NaNO₃ monitored with an RI detector. The flow rate was 1 mL/min, and the temperature was set at 40 °C. Pullulans (P50 to P800) were used for estimating Mw as a standard calibration.

Insoluble dietary fiber (IDF), soluble dietary fiber (SDF), and low molecular weight soluble dietary fiber (LMSDF) were determined using the enzymatic gravimetric/chromatographic method according to McCleary et al. [30 (link)]. LMSDF was estimated by using high performance liquid chromatography in combination with a refractive index detector (HPLC-RI, Hitachi, Düsseldorf, Germany). Parameters for HPLC-RI analysis were as follows: column, TSKgel G2500PWxl (3000 mm × 7.8 mm, Tosoh, Grießheim, Germany), 2× in series; eluent, double distilled water with a constant flow rate of 0.4 mL/min; oven temperature, 80 °C. Total dietary fiber (TDF) was calculated from IDF, SDF, and LMSDF. To structurally characterize IDF and SDF, a preparative isolation procedure of dietary fiber was performed (resulting in preparative IDF/SDF) using, among others, a thermostable α-amylase instead of a pancreatic α-amylase as detailed in [31 (link)]. Because analyses of IDF, SDF, and LMSDF were carried out in duplicate, range/2 was reported as a suitable measure to indicate statistical dispersion.

The molar mass distribution was performed to assess the molecular weight distribution of the crude fucoidans obtained from the two algae by the three ecofriendly intensified extraction technologies. The molar mass distribution profile was also evaluated for U. pinnatifida commercial fucoidan. The HPLC consisted of two columns in series TSKGel G3000PWXL and TSKGel G2500PWXL (300 × 7.8 mm, Tosoh Bioscience, Stuttgart, Germany), with a PWX guard column (40 × 6 mm). The operation conditions were Milli-Q water at 0.4 mL/min as a mobile phase at 70 °C, the standard being dextran from 1000–80,000 Da (Fluka, Newport News, VA, USA). This system was used to study the crude fucoidans obtained from S. muticum. On the other hand, the crude fucoidan obtained from U. pinnatifida was determined using a SuperMultipore PW-H column (6 mm × 15 cm) with a guard column SuperMP (PW)-H (4.6 mm × 3.5 cm, TSKgel Tosoh Corporation, Tokio, Japan). The selected operation conditions to work with this equipment were 40 °C, Milli-Q water as a mobile phase at 0.4 mL/min, and a refractive index detector. Polyethylene oxide at different molecular weights (23,600–786,000 Da) was used as a standard (Tosoh Corporation, Japan).