Aproveitamento de resíduos de Citrus sp. para obtenção de biomassa de Agaricus bisporus.

Abstract

The fruits of the genus Citrus sp. are the most abundant crops in the world, being produced and consumed in different parts of the planet. During the cultivation and processing of Citrus sp., several tons of wastes are generate. These materials have high levels of nutrients, especially the soluble and insoluble sugars, able to biological conversion. The aim of this study was to evaluate the potential of using waste Citrus sp. as a substrate for vegetative growth of Agaricus bisporus, to obtain fungal biomass, by the submerged cultivation technique (liquid phase, LPC) and solid state cultivation (SSC). For LPC it was used the liquid fraction of the mandarin residue (Citrus reticulata) as a source of carbohydrates. Optimization of bioprocess by response surface methodology (RSM) allowed a maximum value of 47.06 g.L-1 biomass of A. bisporus at 8 days, initial pH of 6.0 and temperature of 28°C. However, by analyzing the surfaces responses studied, it was found that a more acidic pH (4.5) can be used without loss in biomass yield. In SSC it was used the solid waste of mandarin and orange (Citrus sinensis), previously crushed and without adding nutrients. For both residues, the development of A. bisporus occurred faster after adjusting pH to 4.5 with CaCO3. The monitoring of bioprocesses was performed by quantification of pectinase activity (PA) of reducing sugars (RS), and total protein (TP) to LPC. The spectroscopy of molecular absorption in the visible was employed as a method of supervision. Application of molecular absorption spectroscopy with infrared fourier transform (FT-IR) associated with regression by partial least squares (PLS) made possible to quantify simultaneously the parameters of LPC with error average forecast quadratic (RMSEP) and determination coefficients (R2) of 0.0012 U.L-1 and 0.9760, 0.23 mmol.L-1 and 0.9956 and 0.03 g.dL-1 and 0.9957, respectively. This study showed two impactful results for the environmental area technology. First, the waste of mandarin and orange can be used as substrate and source of nutrients, mainly in the form of carbohydrates, studied in fermentation processes, obtaining added value bioproducts that can be associated with the biomass of A. bisporus. In addition, monitoring the bioprocess can be accomplished by LPC cleaner technology, using FT-IR and chemometrics associated with the unified method to replace different spectrophotometric methods, more costly and higher reagent consumption.