Desenvolvimento de materiais bioativos e biodegradáveis a partir de polissacarídeos
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2018-10-19
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Universidade Federal de Goiás
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Plastics have become indispensable materials for modern society, with a wide variety of
applications, mainly in the packaging sectors such as food, pharmaceuticals, cosmetics and
chemical inputs. Although they have a number of associated economic advantages, plastics are
responsible for a number of environmental problems, which have reached critical levels in all
countries around the world. In this context, natural polymers appear as potential substitutes for
synthetic polymers, since they have a low associated environmental impact. Cashew gum
polysaccharide (CGP) and starch are materials that have excellent properties for the production of
film-forming matrices, which can be exploited in several biotechnological applications. In this
work, the CGP was evaluated for its potential use as a support for the immobilization of cell wall
degradation enzymes produced by Trichoderma asperellum T00 (TCWDE) and it’s in vitro
bioactivity was evaluated for the ability to inhibit the growth of fungi Aspergillus fumigatus and
Penicillium sp. In addition, CGP films in association with polyvinyl alcohol (PVA) were produced
and the fractional factorial design technique was used to study the effects of composition variation
on its physical, mechanical and morphological properties. The films produced by the casting
technique were analyzed for total carbohydrate content, transparency (wet and dry films),
thickness, maximum breaking force, tensile strength, elongation percentage, structural stability and
swell index in water, sodium acetate buffer and in glycine buffer. The morphology of the films was
evaluated by scanning electron microscopy. The F7 and F8 formulations were bioactivated by
immobilization of trypsin inhibitor molecules: Platypodium elegans trypsin inhibitor (PeTI),
Acacia polyphylla DC trypsin inhibitor (AkTI), Inga laurine trypsin inhibitor (SW.) Willd (ILTI),
and talisin a lectin/trypsin inhibitor isolated from the seeds of Talisia esculenta (St. Hil.) Radlk. In
addition, the starch obtained from the fruits of lobeira (Solanum lycocarpum St. Hil) was used for
the production of an edible packaging destined to the food industry. The results showed that the
best condition for immobilization of EDPCT’s was obtained using the 1.0 mmol L-1 metaperiodate
concentration and immobilization time of 20 min with a maximal activity of immobilized N-
Acetylglucosaminidase (NAGase) of 30.1 (± 0.38) U mL-1. In the optimum immobilization
condition, retention of 93, 41 and 24% was obtained for the enzymes NAGase, chitinase and β-1,3-
glucanase, respectively. The CGP/TCWDE system proved to be very effective in inhibiting the
growth of A. fumigatus, and inhibiting the growth of Penicillium sp. to a lesser extent. The
Transmission Electron Microscopy evidenced the performance of EDPCT's on the cell wall of the
target fungi. The lifetime of the CGP/TCWDE was evaluated during 200 days, where a reduction
of 49.6% of the initial activity was observed after 40 days of dry storage at room temperature (25
°C). After this period, no further loss in activity was detected. The fractional factorial design
revealed that the CGP has positive linear effect on the remaining total carbohydrate properties,
transparency and maximum breaking strength. The PVA, on the other hand, had positive linear
effect on the thickness, transparency, variation of area in water and the percentage of elongation;
negative linear effect on swelling in glycine buffer; and negative quadratic effect on swelling in
water and glycine buffer. The sodium metaperiodate (NaIO4) presented a linear negative effect on
the properties of total carbohydrates remaining, thickness, transparency and water swell index.
Scanning electron microscopy (SEM) revealed that the different formulations of CGP/PVA films
show differences in micropore formation capacity during swelling in water (pH 7.0), in sodium
acetate buffer (pH 4, 5) and in glycine buffer (pH 9.5). Principal component analysis confirmed the
distinct behavior of the formulations and their properties, revealing the existence of three main
components, which together account for 91% of the analyzed properties. Immobilization tests of
trypsin inhibitors by trapping demonstrated greater efficiency in the 24 h immobilization time with
efficiencies of 6.7; 42.5; 3.4 and 93.4% for PeTI inhibitors, AkTI, ILTI and Talisin, respectively.
The films produced from the starch of the lobeira showed high transparency, and excellent
absorption capacity of dyes and food fragrances. These characteristics favor the use of this material
in different segments of the food industry.
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CRUZ, M. V. Desenvolvimento de materiais bioativos e biodegradáveis a partir de polissacarídeos. 2018. 131 f. Tese (Doutorado em Ciências Biológicas) - Universidade Federal de Goiás, Goiânia, 2018.