title: Apple juice clarification by immobilized pectolytic enzymes in packed or fluidized bed reactors.
abstract: The catalytic behavior of a mixture of pectic enzymes, covalently immobilized on different supports (glass microspheres, nylon 6/6 pellets, and PAN beads), was analyzed with a pectin aqueous solution that simulates apple juice. The following parameters were investigated: the rate constant at which pectin hydrolysis is conducted, the time (tau(50)) in which the reduction of 50% of the initial viscosity is reached, and the time (tau(comp,dep)) required to obtain complete depectinization. The best catalytic system was proven to be PAN beads, and their pH and temperature behavior were determined. The yields of two bed reactors, packed or fluidized, using the catalytic PAN beads, were compared to the circulation flow rate of real apple juice. The experimental conditions were as follows: pH 4.0, T = 50 degrees C, and beads volume = 20 cm(3). The initial pectin concentration was the one that was present in our apple juice sample. No differences were observed at low circulation rates, while at higher recirculation rates, the time required to obtain complete pectin hydrolysis into the fluidized reactor was found to be 0.25 times smaller than in the packed bed reactor: 131 min for the packed reactors and 41 min for the fluidized reactors.
authors.affiliation: Department of Experimental Medicine, Second University of Naples, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Diano
authors.forename: Tiziana
authors.initials: T
authors.lastname: Grimaldi
authors.forename: Mariangela
authors.initials: M
authors.lastname: Bianco
authors.forename: Sergio
authors.initials: S
authors.lastname: Rossi
authors.forename: Katya
authors.initials: K
authors.lastname: Gabrovska
authors.forename: Galya
authors.initials: G
authors.lastname: Yordanova
authors.forename: Tzonka
authors.initials: T
authors.lastname: Godjevargova
authors.forename: Valentina
authors.initials: V
authors.lastname: Grano
authors.forename: Carla
authors.initials: C
authors.lastname: Nicolucci
authors.forename: Luigi
authors.initials: L
authors.lastname: Mita
authors.forename: Umberto
authors.initials: U
authors.lastname: Bencivenga
authors.forename: Paolo
authors.initials: P
authors.lastname: Canciglia
authors.forename: Damiano G
authors.initials: DG
authors.lastname: Mita
mesh_terms: D000327:Adsorption; D001628:Beverages / Q000032:analysis*; D019149:Bioreactors; D002384:Catalysis; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005525:Food-Processing Industry; D007700:Kinetics; D027845:Malus / Q000737:chemistry*; D010368:Pectins / Q000737:chemistry; D011096:Polygalacturonase / Q000737:chemistry*; D014783:Viscosity
chemical_list: D004800:Enzymes, Immobilized; D010368:Pectins; D011096:Polygalacturonase