Utilização de resíduos lignocelulósicos de palmito pupunha (Bactris gasipaes) para o cultivo de cogumelo (Pleurotus ostreatus)

Abstract

Fungi of the genus Pleurotus spp. produce enzymes that degrade lignocellulosic material, and can be used in the bioconversion of agroindustrial waste into fruiting bodies (mushrooms). During peach palm processing, about 80% of the stem used in canning becomes waste. The aim of this work was to develop a substrate formulation for Pleurotus ostreatus (shimeji) production using waste from the palm heart processing, and, at the best established condition, to characterize the mushroom in comparison with similar products. In Chapter 1, a rotational central composite design was performed using the independent variables C:N ratio (varied according to the ratio of leaf sheath to heart of palm) and substrate moisture, with mushroom yield as the dependent variable. Cultivation was performed on medium with sawdust and wheat bran (C:N of 70 and moisture of 54%) as a yield standard. The condition of C:N of 69.14 and humidity of 86.2% was validated (yield of 24.47%) and used to raise the production costs of shimeji based on the monthly production of a peach palm processing unit. With the estimate of operational costs of production, it is concluded that the producer can generate a monthly income of approximately R$43,595.00, from the production of 1.8 tons of mushrooms. In chapter 2, samples of P. ostreatus cultivated in the condition of higher yield were compared to the sample cultivated in standard medium and commercial samples of P. ostreatus and Agaricus bisporus (champignon) regarding the proximate composition and content of phenolic compounds by the method with Folin-Ciocalteu reagent. A Central Composite Planning was performed varying the ethanol concentration and extraction time. The extracts that presented the highest content of phenolic compounds were evaluated for antioxidant activity by the ABTS+ and FRAP radical methods and submitted to chromatographic analysis for identification and quantification of phenolic compounds. As for the proximate composition, the shimeji samples presented a higher content of dietary fiber in relation to the champignon, and a lower content of lipids and ash. The highest protein content was obtained in the commercial shimeji sample (28.44%), followed by champignon (19.76%), shimeji grown on sawdust (16.25%) and in the palm heart waste (16.09%). The content of phenolic compounds ranged from 1.29 to 2.57 mg AGE/g sample and 2.66 to 3.60 mg AGE/g sample for P. ostreatus and A. bisporus extracts, respectively. The best extraction condition of phenolic compounds for P. ostreatus was with ethanol concentration at 29.4% and extraction time of 38.8 min and for A. bisporus sample was with 29.4% ethanol and extraction time of 81.2 min. Regarding the antioxidant activity, the extract of A. bisporus showed the highest activity, followed by P. ostreatus grown on palm residue, commercial and standard medium. The content of phenolic compounds in the extracts was directly proportional to the antioxidant activities of the samples. Regarding the chromatographic analysis, gallic, vanillic, trans-cinnamic, ferulic and coumaric acids were identified in the extracts of the four mushroom samples analyzed, and gallic acid showed a positive correlation with the ABTS and FRAP antioxidant methods and vanillic acid showed a positive correlation with the ABTS method.