Hemp Enzymatic Retting

Enzymatic retting applies pectinase (polygalacturonase, pectin lyase at 0.05–0.5% owf) combined with xylanase (0.02–0.2% owf) and chelating agents (EDTA 1–5 mM removing Ca²⁺ from pectate bridges) at 40–55°C, pH 4.5–6.0 for 8–24 hours, producing the highest quality hemp fibre of any retting method. Bundle fineness of Nm 8–20 (versus Nm 4–10 for dew retting) and strength retention of 85–95% of unretted fibre are achieved through targeted pectin degradation without cellulose or hemicellulose attack. Fibre uniformity CV% of 15–20% is the lowest of all retting methods. Process water consumption is 20–30 L/kg stem; enzyme cost adds €0.15–0.30/kg fibre. BOD of effluent is 500–2,000 mg/L (versus 5,000–20,000 mg/L for water retting), requiring primary treatment before discharge. Enzymatic retting is adopted by premium hemp textile producers in Netherlands, Belgium, and Canada for fine yarn (Nm 15–30) applications in apparel and medical textiles where fibre fineness and uniformity are critical quality parameters.