Application of enzymes for efficient extraction, modification, and development of functional properties of lime pectin

The objective of the present study was to transform “Waste to Food” using enzymes to recover value-added food ingredients from biomass. Six commercial cellulases were screened to generate proof of concept that enzymes are selective and efficient catalysts for opening of lime peel biomass to recover pectin.

The most efficient enzyme preparation was Laminex C2K derived from Penicillium funiculosum which, during 4 h treatment at pH 3.5, 50 °C, released pectin with similar yield (23% w/w), molecular weight (69 kDa), and functional properties e.g. gelling, stabilization of acidified milk drinks and viscosity as the classically acid-extracted pectins (8 h treatment at 70 °C, pH < 2).

Carbohydrate microarray analysis showed that enzymatically extracted pectin mainly contained highly methylated pectin (chemical compositional analysis indicated degree of esterification up to 82%), whereas acidically extracted pectins were more heterogeneous with regard to degree of esterification and had lower degrees of esterification (67–74%).

A high degree of esterification in enzymatically extracted pectin may be directly exploited commercially as the so-called Ultra-Rapid-Set pectin, which gels particularly fast at higher temperatures. The Laminex CK2 extracted pectin polymers were not sensitive to the presence of Ca2+ ions, they formed a gel at low pH in the presence of sugar and were able to stabilize acidified milk drinks.

Further modification by enzymatic de-esterification of the pectin extracted with Laminex C2K improved its calcium sensitivity and ability to stabilize acidified milk drinks. The present study demonstrates that it is possible to substitute classical acid-based extraction by enzymatic catalysis and obtain pectin products with desirable functional properties.