Optimization of enzymatic hydrolysis conditions for extraction of pectin from rapeseed cake (Brassica napus L.) using commercial enzymes

• Enzymatic hydrolysis condition for RSC pectin extraction has been optimized.
• Commercial enzymes, Celluclast and Alcalase, were used.
• The loss of galactose was minimized at 270 min or the enzyme–RSC ratio of 1:50.
• Two enzymes generated a significant synergistic effect on the pectin yield.
• The highest pectin yield was obtained at the Celluclast–Alcalase ratio of 1:4.

The aims of this study were to extract pectin from rapeseed cake (RSC) by enzymatic hydrolysis using commercial enzymes (Celluclast and Alcalase) and to investigate the effects of different reaction conditions, such as enzymatic hydrolysis time, enzyme–RSC ratio, and Celluclast–Alcalase ratio, on the degradation of RSC and pectin yield. RSC was treated using a combined extraction process that consisted of a fat removal process, enzymatic hydrolysis, and isopropanol/ethanol precipitation. After the fat removal process and enzymatic hydrolysis, defatted-RSC was suitably decomposed, and the loss of liberated reducing sugars was minimized when the hydrolysis condition reached a hydrolysis time of 270 min or an enzyme–RSC ratio of 1:50. Based on these results, various Celluclast–Alcalase ratios were applied. Alcalase led to the destruction of protein–carbohydrate complex in defatted-RSC, whereas Celluclast cleaved some linkages of carbohydrate slightly. As a result, the highest pectin yield was 6.85% at the Celluclast–Alcalase ratio of 1:4.