The surface-enhanced Raman scattering (SERS) of sodium alginates and their hetero-and homopolymeric fractions obtained from four seaweeds of the Chilean coast was studied. Alginic acid is a copolymer of β-D-mannuronic acid (M) and α-L guluronic acid (G), linked 1 → 4, forming two homopolymeric fractions (MM and GG) and a heteropolymeric fraction (MG). The SERS spectra were registered on silver colloid with the 632.8 nm line of a He-Ne laser. The SERS spectra of sodium alginate and the polyguluronate fraction present various carboxylate bands which are probably due to the coexistence of different molecular conformations. SERS allows to differentiate the hetero-and homopolymeric fractions of alginic acid by characteristic bands. In the fingerprint region, all the poly-D-mannuronate samples present a band around 946 cm −1 assigned to C-O stretching, and C-C-H and C-O-H deformation vibrations, a band at 863 cm−1 assigned to deformation vibration of β-C 1 -H group, and one at 799-788 cm −1 due to the contributions of various vibration modes. Poly-L-guluronate spectra show three characteristic bands, at 928-913 cm −1 assigned to symmetric stretching vibration of C-O-C group, at 890-889 cm −1 due to C-C-H, skeletal C-C, and C-O vibrations, and at 797 cm −1 assigned to α C 1 -H deformation vibration. The heteropolymeric fractions present two characteristic bands in the region with the more important one being an intense band at 730 cm −1 due to ring breathing vibration mode.

Innovative biocomposites from residual microalgae biomass (RMB), a byproduct of biodiesel production, and PBAT (poly­(butylene adipate-co-terephthalate)) have been prepared in this study. RMB was characterized by Fourier transform infrared spectroscopy (FT-IR) and its thermal stability was determined. Subsequently, RMB and PBAT biocomposites were prepared by extrusion and injection molding. Incorporation of 10, 20 and 30% RMB in the biocomposites was studied. The biocomposites were characterized using FT-IR and thermogravimetric analysis, and their mechanical properties were compared, including tensile, flexural and impact strength. The effect of RMB on the morphology of the polymer matrix was analyzed by scanning electron microscopy and confocal laser scanning microscopy. RMB plasticization was performed with glycerol and urea, comparing different proportions of glycerol and urea. The studies show that it is possible to use RMB in the manufacture of biocomposites with PBAT, obtaining the best extrusion results with 20% RMB. Optimal result was achieved with 30% glycerol and 7.5 phr of urea.

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The anthocyanin content of grape pomace from different Chilean grape varieties (Vitis vinifera var. Cabernet Sauvignon, Carménère and Syrah) from two vineyards (Misiones de Rengo and Miguel Torres) was determined by the differential pH method and the anthocyanin perfile was characterized by HPLC. In all chromatograms, a major peak corresponding to malvidin-3-O-glucoside was observed. Also, the in vitro antifungal activity of these extracts against mycelia growth of the phytopathogenic fungus Botrytis cinerea was evaluated. The anthocyanin containing extract from Cabernet Sauvignon grape pomace of Misiones de Rengo vineyard was the most active. The extract from the same variety form Miguel Torres vineyard did not inhibit mycelia growth of B. cinerea. In general, the other extracts were less active against the fungus.