Enzymatic extraction of pectin from passion fruit peel (Passiflora edulis f. flavicarpa) at laboratory and bench scale

Passion fruit peel, a waste product from the fruit processing industry, was used as feedstock for pectin extraction. For this purpose, a novel process was developed at flask scale using a crude extract of the fungal enzyme protopectinase-SE. The enzymatic pectin extraction was compared with the classic chemical extraction and scaled-up to 7 L stirred tank bioreactor. Pectin yields (measured as galacturonic acid) of 17–26 g/100 g of dry peel were achieved with the enzymatic extraction, which were 6–40% higher than that obtained with the traditional chemical extraction method. Effect of agitation speed, enzyme loading, pH, and temperature were evaluated, and all factors but agitation speed had a significant effect on the pectin yield. Best yields were obtained using 30 U/mL of protopectinase-SE loading at pH 3.0 and 37 °C. Scale-up to bench scale (7 L bioreactor) was successful using Reynolds or Froude number as scale-up criteria, achieving similar yields to those obtained in flasks, but with a slightly lower extraction rate. Enzymatic extracted passion fruit pectin had a galacturonic acid content of 85 g/100 g and a degree of esterification of 68%, similar to commercial citrus pectin.