Isolation and characterisation of cassava linamarase using centrifuge and cross flow membrane
Obazu, Franklin Ochuko
Linamarase application exists in biotechnology such as potentiometric sensors for linamarin by coupling linamarase from cassava leaf with a cyanide ion-selective electrode and to measure glucose in biomedical applications. It is used in a batchwise process to detoxify fermenting cassava during ‘garri’ production. Linamarase along with its naturally occurring substrates, linamarin and lotaustralin, is found in a variety of edible plant tissues such as those of cassava from which garri is produced. However, the separation and purification of linamarase at reasonable large quantity for these applications from plants has been a challenge. In the study a miniflex Ultrafiltration (UF) Cross Flow obtained from Schleicher and Schuell (Germany) was used for linamarase isolation and purification from cassava tissues. Membranes with different pore sizes of 0.45, 0.2, 0.1 and 0.02 μm, made from polyethersulfon screnes and silicone adhensives, with surface area of 2.4 mm2, were experimented. Fluxes were observed to decrease very sharply from 0.45 to 0.02μm membrane pore sizes. No permeate was collected from 0.1 and 0.02 μm membranes due to concentration polarisation and clogging of these membranes. Permeate and retentate from 0.45 and 0.2 μm membrane contained linamarase, while the retentate of the 0.1 and 0.02 μm membranes contained linamarse and that no permeate was collected from 0.1 and 0.02 μm membranes due to the fouling and clogging of the small membrane pores. It was therefore concluded that linamarase was finally purified by the 0.2 μm membrane. A simple mathematical model derived from the Hagen-Poiseuille equation could not predict the linamarase flux data, perhaps due to the effect of concentration polarisation, which led to the proposition of the Langmuir adsorption isotherm. It was interesting to observe that the plot of 1/v versus 1/Δp from the use of the Langmuir equation gave a linear relationship from which the linamarase flux iii was predicted. The standard error between the experiment and the model was 0.011, which is a good measure of the agreement between data. The Langmuir adsorption isotherm therefore predicts the fouling and concentration polarisation of the membrane during linamarase purification from cassava tissues. This proposition was supported by the solute deposits on the pores and surface of the membrane where van der Waal forces were created between the molecules, thus resulting in the fouling and chemical polarisation.
Linamarase Cassava Linamarase preparation Enzyme isolation Membrane technology