Pectinase immobilized on magnetic nanoparticles coated with alginate for pectin hydrolysis in guava juice assisted by a stirred electromagnetic reactor.

Aspergillus aculeatus pectinase was immobilized on magnetic nanoparticles coated with calcium alginate for pectin hydrolysis in guava juice by a stirred electromagnetic reactor (SER). The average crystallite size estimated by the Scherrer formula was 33.7 nm. The reaction rate in SER (701.7 U/mL) was almost twice that of the static process (362.5 U/mL). Both processes displayed a sigmoidal trend with positive cooperativity (n) of 5 and 4, respectively. Both free and immobilized pectinase showed great performance in the pH range of 4.0-7.0. After immobilization, pectinase acted optimally at 50 °C. Pectin hydrolysis was performed for over 10 successive cycles in SER losing only 30% of its initial activity. Thermodynamic activation parameters of the reaction revealed higher spontaneity and efficiency when hydrolysis was performed in SER. Pectin hydrolysis in guava juice displayed 41% turbidity and 85.5% viscosity reduction. The electromagnetic reactor displayed great potential for performing hydrolysis of pectin in guava juice. The biocatalyst showed good features for further applications in food industries.