Application crude multienzyme extract from Aspergillus niger as a pretreatment for the extraction of essential oil from Croton argyrophyllus leaves.

Leaves of Croton argyrophyllus contain essential oil with promising active components for the development of drugs and botanical insecticides. In this study, we evaluated the enzymatic pretreatment process to increase the extraction of essential oil from fresh and dried leaves of C. argyrophyllus. Pretreatment was carried out using a crude multienzymatic extract obtained via solid-state fermentation of forage palm by Aspergillus niger, and the extraction was performed by hydrodistillation. A Doehlert matrix was used to optimize the enzymatic pretreatment variables temperature and enzymatic extract. The effect of pretreatment time was also investigated. At optimum experimental conditions, 41.34°C, 140 min, and 130.73 mL of enzyme in 369.27 mL of water, the essential oil yield from fresh leaves subjected to enzymatic pretreatment increased by 9.35% and that from dry leaves by 6.77%. Based on chromatographic analysis (GC-MS), no compound was degraded in the extraction process. Micromorphological analysis confirmed the rupture of the glandular trichomes, favoring essential oil release. Therefore, enzymatic pretreatment associated with hydrodistillation increased the essential oil yield and is a promising application to obtain essential oil for therapeutic purposes without altering its composition.

Application of a constrained mixture design for lipase production by Penicillium roqueforti ATCC 10110 under solid-state fermentation and using agro-industrial wastes as substrate.

Solid state fermentation (SSF) simulates the natural conditions fungal growth, where the amount of water in the reaction medium must be restricted, thus limiting the use of liquid substrate. An analytical strategy to deal with this limitation is the design of blending with constraints. Thus, the objective of the work was to optimize two constrained waste mixtures for the production of lipase by Penicillium roqueforti ATCC 10110 under SSF, using different substrates that combine solid and liquid waste. For this, the best fermentation time was determined through a fermentative profile, afterwards a restricted-mix design with lower and upper limits of the components of mixture I (cocoa residue, solid palm oil residue and liquid palm oil residue) and II (cocoa residue, mango residue and palm oil residue liquid palm) was applied. By means of Pareto and contour graphs, the maximum production points of lipase in mixtures I (6.67 ± 0.34 U g-1) and II (6.87 ± 0.35 U g-1) were obtained. The restricted mixture design proved to be a promising tool in the production of lipase by P. roqueforti ATCC 10110 under SSF since the use of restrictions is useful when intending to combine solid and liquid residues in fermentation processes.

Development of amperometric biosensor in modified carbon paste with enzymatic preparation based on lactase immobilized on carbon nanotubes.

ABSTRACT: The variety of products derived from milk, without or with lactose, encourages the development of more effective analytical techniques that can be applied to the quality control of both the production line and the final products. Thus, in this work an efficient and minimally invasive method for the detection of lactose was proposed, using a biosensor containing the enzyme lactase (LAC) immobilised on carbon nanotubes (CNTs) that, when reacting with lactose, emit an electrochemical signal. This biosensor was connected to a potentiostat, and its electrochemical cell was composed of the following three electrodes: reference electrode (Ag/AgCl), auxiliary electrode (platinum wire), and working electrode (biosensor) on which graphite (carbon) paste (CP), CNTs, and LAC were deposited. The transmission electron microscopy and scanning electron microscopy were used in the characterisation of the composite morphology, indicating excellent interactions between the CNTs and LAC. The sensitivity of the CP/LAC/CNT biosensor was determined as 5.67 µA cm-2.mmol-1 L and detection limits around 100 × 10-6 mol L-1 (electrode area = 0.12 cm2) and an increase in the stability of the system was observed with the introduction of CNTs because, with about 12 h of use, there was no variation in the signal (current). The results indicate that the association between the CNTs and LAC favoured the electrochemical system.