Effects of pH control with phthalate buffers on hot-water extraction of hemicelluloses from spruce wood

► We extract high-molar-mass GGMs with pressurised hot water from spruce in high yield. ► Extraction with and without phthalate buffer addition are compared. ► Such extraction is strongly dependent on the pH in a narrow region around pH 4. ► Control of pH to around 4 gives similar or higher yield of GGM extraction. ► Control of pH to around 4 also gives higher average molar mass of GGM extracts.