Parameters in preparation and characterization of cross linked enzyme aggregates (CLEAs)

1Pectin cross-linked enzyme aggregates (pectin-CLEAs) of glucoamylase were prepared for 2 the first time with pectin as cross-linking agent. Pectin as biocompatible, biodegradable, non-3 toxic, renewable and macromolecular cross-linker was used instead of traditional micro-4 molecular glutaraldehyde cross-linker. Cross-linker was prepared by controlled sodium 5 metaperiodate oxidation of native pectin. The effects of precipitant type, amount of 6 precipitant and cross-linking on activity recovery of glucoamylase in pectin-CLEAs were 7 studied. After aggregation of glucoamylase with ammonium sulphate, when formed 8 aggregates were cross-linked by pectin, 83% activity recovery was achieved in pectin-9 CLEAs, whereas when cross-linked by traditional cross-linker glutaraldehyde, 64% activity 10 recovery was achieved in glutaraldehyde-CLEAs. After formation of pectin-CLEAs and 11 glutaraldehyde-CLEAs, optimum temperature for glucoamylase activity was shifted from 50 12 to 55°C. The free enzyme and pectin-CLEAs displayed optimal pH 5, whereas optimal pH of 13 glutaraldehyde-CLEAs was shifted to pH 6. Compared with free enzyme and glutaraldehyde-14 CLEAs, lower inactivation rate constant of glucoamylase in pectin-CLEAs within the 15 temperature range of 50-70°C was observed. Moreover, activation energy required for 16 denaturation of glucoamylase in pectin-CLEAs was higher than glutarldehyde-CLEAs and 17 free enzyme. Kinetic studies show that the K m and V max of glucoamylase remained 18 unchanged after pectin-CLEAs formation, whereas K m was increased and V max was decreased 19 after glutaraldehyde-CLEAs formation. Finally upon 10 consecutive uses, pectin-CLEAs 20 retained 55% initial activity and glutaraldehyde-CLEAs retained only 29% initial activity. 21These results suggest that this pectin-CLEA is potentially usable in industrial applications. 22

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The solvent‐segregation of linseed oil using furfural and mixtures of furfural and hexane as solvents has been investigated at 15°, 24.5° and 35°. Lower temperatures and higher percentages of hexane lead to maximum separation. An extract fraction (about 16%) having an iodine value of 209 has been obtained under these conditions. Equilibrium curves useful in designing multi‐stage counter‐current extraction columns are presented.

Bibliography Molecular S t r i d w eGaunt, J , , Trans F a r a d qThe solvent segregation of safflower oil using furfural and mixtures of furfural and hexane has Little or no segregation is effected, presumably because of the absence of been investigated. linoleno-type glycerides in the oil.