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ABSTRACT

Mango seeds from agro‐industry represents an environmental problem due to the amounts of by‐products produced. Conversely, poly (lactic acid) (PLA) is a potential green alternative to conventional plastics. The goal of this study aimed to develop a biocomposite based on PLA and mango’s by‐product for rigid packaging. Six biocomposites are obtained by extrusion/injection processing using formulations with PLA as a matrix and up to 20% by weight of mango seed’s by‐products. The materials are characterized by chemical and physical analysis; scanning electron microscopy/energy dispersive X‐ray, X‐ray diffraction; Fourier transform infrared spectroscopy (FTIR); thermal gravimetric analysis/differential thermogravimetry; differential scanning calorimetry (DSC), and mechanical analysis. FTIR bands and DSC transitions related to starch are higher in the kernel, while more cellulose bands are found in the integument. Kernel presented thermal degradation in the biocomposites, the sample PLA+20 wt% kernel. For the other compositions, it is possible to observe that they could keep their morphology. Significant improvements in both mechanical and barrier properties are found in the formulation with 20 wt% integument (up to 38% in elastic modulus). Therefore, this study suggests that biocomposites developed from PLA / Integument / Kernel have potential as a new biomaterial for rigid food packaging systems.

The Brazil nut (Bertholletia excelsa) is an economically important product to the Brazilian Amazon. Currently, its marketing is being affected by the high incidence of aflatoxins (AF) produced by potentially aflatoxigenic fungi associated with its seeds. In this context, the purpose of this study was to determine which part of the nut contributes to contamination by aflatoxins and to identify the mycobiota in Brazil nut samples. Unshelled and shelled nuts were analyzed by measuring the total count of filamentous fungi (Aspergillus sections Flavi, Nigri and Circumdati) in sanitised and non-sanitised treatments. The isolates identified as Aspergillus section Flavi, the major producers of AF, were plated for determination of their aflatoxigenic potential. To perform the AF analysis, samples of Brazil nuts were treated separately. The AF from the shell and kernel were extracted by chloroform and analysed by the HPLC-FD system in isocratic mode. The Aspergillus section Flavi count was 21.67% lower. The production of AF by the isolated fungi was 30% for sanitised and 23.8% for non-sanitised samples. The concentrations obtained of AFB 1 and AFG 1 were higher than those of AFB 2 and AFG 2 . The AFB 1 concentrations of shelled nuts and shell samples were 35.0 and 1.78 lg/kg, respectively. AFB 2 and AFG 2 were detected only in shelled nut samples. The HPLC-FD analysis presented limits of detection (LOD) and quantification (LOQ) of 0.2 and 0.4 lg/kg, respectively.