The application of phytases for animal feed in developing countries is limited due to the high cost of these enzymes, determined by the importation fees and the expensive substrates used for their production. In this work, we have used agroindustrial byproducts for the production of extracts containing phytases, which were accessed for their stability focusing on the conditions found in the gastrointestinal tract of pigs. The fungus Acremonim zeae presented higher phytase production in medium containing cornmeal, while the yeast Kluyveromyces marxianus produced 10-fold more phytase when cultivated on rice bran. Process optimization increased the difference in productivity to more than 300 fold. The phytase from A. zeae was thermostable, with higher activity at neutral pH and 50 °C, but was inhibited at pH 2.5 and by various ions. The phytase activity in the K. marxianus extract was stable at a wide range of conditions, which indicates the presence of at least two enzymes. As far as we know, this manuscript describes for the first time the phytase production and the characteristics of the extracts produced by both these microbial species. These enzymes could be produced at low cost and have potential to replace enzymes currently imported for this purpose.

In the present study, soy protein isolate (SPI) multifunctional bioplastics were prepared by casting, with the addition of tannins extracted from Stryphnodendron adstringens and kraft lignin. The films were obtained through biopolymer composites and blends method, prepared at three pHs (8.5, 9.5 and 10.5) and characterized by thermochemical studies, Fourier-transform infrared spectroscopy, scanning electron microscopy, water vapor permeability (WVP), antioxidant activity, water contact angle, surface energy, wettability, and mechanical tests. The composites presented better results when compared to the blend and control films, respectively, in the polarity, hydrophobicity, WVP and especially in the antioxidant activity tests. Nevertheless, no significant difference between the samples was noticed in the thermochemical and spectroscopic studies. The results presented the potential of the composites to produce SPI biopolymers with tannins and kraft lignin, leading to the development of multifunctional materials as an alternative for sustainable packaging.

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