Effect of laccase oxidation pre-treatment on coffee (Coffea arabica) bean processing waste for composting substrate

Laccase oxidation pre-treatment on coffee pulp and husk in this study was expected to improve the quality of compost by removing phenol compounds which can be toxic for microorganisms. The purpose of this study was to determine the effect of pre-treatment of laccase oxidation on coffee bean processing waste (Coffea arabica) consisted pulp and husk by determining the total phenol, reducing sugar, organic materials and compost quality. Optimization of laccase production was carried out on 5 types of fermentation medium. All parameters except organic materials were measured spectrophotometrically. The results showed that the highest laccase activity (1081.2 U/ml) was achieved by E medium fermentation which contained 0.45 g of rice husk and 0.1 g glucose as carbon source, some of minerals and without the addition of sawdust and CuSO₄. The lowest total phenol and reducing sugar were achieved coffee pulp and husk with laccase oxidation and ABTS pre-treatment as 0.007 ± 0.07 mg/ml and 3.29 ± 0.19 ppm respectively. It can be concluded that indeed pre-treatment of laccase oxidation did not affect the levels of organic matters. All experiment group of pre-treatment showed higher of Total Plate Counts (TPC) comparing to the control. However, the initial oxidation treatment did not have an effect on the levels of N, P, K, C, and the C / N ratio of compost produced when compared to controls. The results of this study could contribute to the process of making compost with the best quality that is environmentally friendly.