Banca de DEFESA: KARINA CARVALHO DE SOUZA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : KARINA CARVALHO DE SOUZA
DATE: 02/08/2023
TIME: 09:00
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

PRODUCTION AND EVALUATION OF BACTERIAL CELLULOSE IN LOW COST CULTURE MEDIA FOR APPLICATION IN SUSTAINABLE PACKAGING

KEY WORDS:

Bacterial celulose; Rice and Corn Starch; Saline médium; Packaging.

PAGES: 107
BIG AREA: Engenharias
AREA: Engenharia Química
SUMMARY:

Cellulose, represented by the formula (C6H10O5)n, is a polysaccharide that can be of vegetable or microbial origin. Its bacterial production, due to its high degree of purity and properties, has potential for applications in the medical, pharmaceutical, cosmetics, food, packaging, composites industries, among others. The production of pure cellulose nanofibrils by bacteria of the genus Komagataeibacter occurs from the consumption of glucose in the medium, metabolized into cellulose by the microorganisms. In this study, the tests were divided into three stages: the first was performed using starch, present in rice and corn grains, as a carbon source for BC production. For this, the starch was hydrolyzed by fungi (Aspergillus oryzae) to obtain glucose, used for the production of BC. The results obtained showed a maximum yield of 2.80 ± 0.43 g / L of BC obtained with the hydrolyzed rice medium. In the second stage of the experiments, the production of BC was carried out using a saline solution, of its own composition, with the addition of carbohydrates and/or proteins (Glucose, Glycerol, Sucrose, Fructose, Peptone, Yeast Extract or Mannitol) as carbon sources . The maximum yield of 5.72 ± 0.01 g / L of BC was obtained with the medium containing Sucrose. In the third stage, the prototype of a sustainable package, with characteristics of a paper package, was developed. All materials produced were characterized in terms of morphology (Scanning Electron Microscopy - SEM), crystallinity (X- ray Diffraction - DRX), thermal stability (Thermogravimetric Analysis - TGA) and analysis of functional groups (Infrared with Fourier Transform - FTIR) . In the first stage of the characterizations, the FTIR confirmed the functional groups present in the BC, as well as the absence of contaminants from the production process. XRD evaluation showed crystallinity around 55%. The TGA analysis revealed that the polymers formed from the alternative media (Rice or Corn) obtained greater thermal stability. SEM showed a non-uniform structure with the random arrangement of nanofibrils. In the second stage of characterization, the diffractograms revealed a crystallinity that varied from 31% (CB-Yeast Extract) to 66% (CB-Fructose) and the FTIR analysis confirmed the existing functional groups in the bacterial cellulose, without possible contaminants. The TGA of the CB-Yeast extract and CB-Mannitol biopolymers revealed maximum degradation temperatures (Tmax.) of 350.7 oC and 322.0 oC, respectively. From the micrographs, CB-Glucose and CB-Sucrose had areas of more dispersed and visible fibrillar structures compared to the others. Finally, the characterizations of the CB-Paper used in the development of a packaging prototype presented Tmax. of 311.8 oC and crystallinity 86.42% with characteristic peaks of cellulose and calcium carbonate present in papers. In the SEM investigation, fibrous and nanometric morphology were observed together with calcite fillers. Therefore, studies like this present new culture media for the production of BC, as well as an important application for these biopolymers, in order to create alternatives to vegetable cellulose, used, for example, in the food packaging industry. 

COMMITTEE MEMBERS:
Externa à Instituição - CRISTIANA MARIA PEDROSO YOSHIDA - UNIFESP
Externo ao Programa - 1056845 - FELIPE PEDRO DA COSTA GOMES - nullPresidente - 2572606 - GLORIA MARIA VINHAS
Externa ao Programa - 2116297 - SARA HORACIO DE OLIVEIRA MACIEL - nullInterno - 1354207 - SEVERINO ALVES JUNIOR