Characterization of Pinus nigra var. laricio Maire bark extracts at the analytical and pilot scale

Pinus nigra var. laricio bark and its hot-water extracts (HWE) obtained at an analytical and pilot plant scale have been characterized in terms of phenolic extractives, condensed tannins (CTs), carbohydrates and inorganic compounds. Analytical extractions with aqueous acetone were also performed for comparison with HWE. The bark contains 35.5 g kg−1 CT, and two-thirds of it could be extracted. Analytical HWE at 75°C led to a total yield of 56.4 g kg−1. The extracts are mainly composed of phenolic compounds (50.7%) and pectins (19.7%). CTs amount to 17.9% of the extracts and are procyanidins with a mean degree of polymerization (DP) of about 9. Non-tannin phenolic oligomers also occurred in the extracts, which could be identified by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) as lignin fragments. Matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF MS) revealed that the CT is a flavanol derivative in methylated form. Further characterization and tailoring of the HWE properties is needed in the context of their specific application.