Microwave-assisted solvent-free extraction of essential oil from Coleus aromaticus: anti-phytopathogenic potential for fruit post-harvesting.

This work evaluates the fungicidal effect of essential oil from Coleus aromaticus (C. aromaticus) by solvent-free microwave-assisted extraction with a yield of 0.54%. Fourier-transform infrared spectroscopy was utilised to identify the functional groups, which were O-H, C-O, C-H, and C=C. Gas chromatography-mass spectrometry analysis was performed to determine the primary essential oil components, namely, thymol (92.62%), thymoquinone (2.64%), creosol (1.77%), linalool (1.68%), p-Cymene-2,5-diol (0.73%), and p-Cymene (0.56%). The inhibitory effect of essential oil extracted from C. aromaticus against the isolated fungi, Aspergillus niger from mango, was investigated. The mycelial growth inhibition of the extracted essential oil by the poisoned food test and disc diffusion assay showed the reduction at 79.63 ± 1.7 and 70.45 ± 6.54%, respectively. In vivo experiment was conducted with artificially wounded and unwounded mangoes, applying the extracted essential oil to the wounded mangoes inoculated with A. niger that could decrease the disease incidence from 100 to 58.33 ± 14.43%. Meanwhile, the treatment of the extracted essential oil did not affect the quality of the mango and it also shows improvement in weight loss reduction of the mango in comparison to the chemical fungicide and untreated mango. Hence, essential oil from C. aromaticus by solvent-free microwave-assisted extraction could be used as an effective control for the fruit spoilage and potential source of fruit preservative.

Pilot-scale production of lipase using palm oil mill effluent as a basal medium and its immobilization by selected materials.

A pilot-scale production of lipase using palm oil mill effluent (POME) as a fermentation basal medium was carried out, and parameters for immobilization of the produced lipase were optimized. Lipase production in a 300-L bioreactor was performed using two proposed strategies, constant power per volume (P/V) and constant tip speed. Moreover, lipase immobilization on different materials was also investigated. Lipase production was performed using liquid-state bioconversion of POME as the medium and Candida cylindracea as the inoculum. The fermentation medium was composed of 1% total suspended solids (TSS) of POME, 0.5% (w/v) peptone, 0.7% (v/v) Tween-80, and 2.2% inoculum. The medium composition was decided on the basis of the medium optimization results of a previous study. The fermentation was carried out for 48 h at 30°C and pH 6. The maximum lipase production was 5.72U/mL and 21.34 U/mL, obtained from the scale-up strategies of constant tip speed and P/V, respectively. Four accessible support materials were screened for their potential use in immobilization. The most suitable support material was found to be activated carbon, with a maximum immobilization of 94%.