RESUMEN
The influence of particle size and solvent flow rate on the kinetics of oil extraction from soybean (eight fractions from 0.433 to 0.122 mm) was studied using hexane, simulating commercial percolation type extractor. The reduction in particle size from 0.433 mm to 0.141 mm showed an increase in the oil yield. However, further reduction to 0.129 mm and 0.122 mm affected the yield due to bed compaction, reducing porosity and contact area. The yield (21.5%) of the ground mass was similar to the major mass fractions (0.239-0.353 mm). The rate of extraction increased drastically with the solvent flow rate. The highest flow rate (9.67 mL/min) exhibited the highest mass transfer coefficient (km) 1.62 × 10-3 s-1 and the diffusion coefficient (De) 1.77 × 10-12 m2/s. At 7.33 mL/min, the yield and the rate of extraction were optimal and no potential benefits were obtained at higher flow rates. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05554-6.
RESUMEN
Tyrosinase, in the presence of oxygen, is the main culprit in post harvest browning of food products, resulting in the drop in its commercial value. In an effort to seek natural tyrosinase inhibitors for food applications, a screening programme was undertaken. Of the 26 fungal cultures isolated from soil samples of Agumbe forest, India, one isolate S16, identified as Aspergillus niger, gave an inhibition of 84 % against the enzyme. The inhibitor was isolated by following an enzyme inhibition assay guided purification protocol. The structure of the inhibitor was elucidated and found to be kojic acid. The IC50 of the Competitive inhibitor was found to be 8.8 µg with a Ki of 0.085 mM.
RESUMEN
A number of isolates from different ecosystems were screened for their ability to inhibit tyrosinase resulting in the selection of isolate CFR 101, which showed an inhibition of 72%. The metabolites present in the crude extract of the selected isolate was profiled through high-performance liquid chromatography (HPLC) before the enzyme inhibition assay to reveal a 66% decrease in area of the peak at room temperature for 13.9 min, after the assay. Upon purification, this peak was identified as kojic acid, a known inhibitor of tyrosinase. This unique technique of combining a reaction assay mixture with HPLC profile wherein inhibitors can be rapidly pinpointed in crude extracts addresses the drawback of rapid chemical high-throughput screening (HTS) systems, which is limited to the chemical nature of metabolites without any evidence of their biological activities.