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Master's Dissertation
DOI
10.11606/D.85.2017.tde-31102017-153157
Document
Author
Full name
Gilberto Dias da Silva
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2017
Supervisor
Committee
Mastro, Nélida Lúcia Del (President)
Cosentino, Helio Morrone
Gennari, Solange Maria
Title in Portuguese
Ressonância paramagnética eletrônica e espectroscopia de infravermelho aplicada no estudo de amidos irradiados
Keywords in Portuguese
amido
EPR
FTIR
radiação gama
Abstract in Portuguese
O amido é o mais abundante dos polissacarídeos de armazenamento de energia de plantas, usualmente depositado na forma de grânulos no citoplasma das células. Também é a principal fonte de energia para o homem, compondo 80-90% dos polissacarídeos da dieta humana, e é o principal responsável pelas propriedades tecnológicas que caracterizam grande parte dos produtos processados. O presente trabalho teve como objetivo a aplicação da ressonância paramagnética eletrônica (RPE) e espectroscopia de Infravermelho por transformada de Fourier (FTIR) ao estudo de amidos irradiados. Amostras em pó de dois amidos naturais, batata (bulbo) e milho (cereal) e farinha de mandioca fermentada ou polvilho azedo (raiz) foram submetidos à ação da radiação ionizante de fonte de 60Co Gammacell 220 com doses de 10, 20 e 30 kGy, taxa de dose de 1kGy h-1. Foram registrados e comparados os espectros de RPE dos três tipos de amidos irradiados e não irradiados. Os amidos apresentaram espectros de RPE semelhantes variando apenas na intensidade do sinal de radicais livres que acompanhou o incremento da dose. Foram estabelecidas as curvas de decaimento para cada um dos amidos ensaiados. No caso de amido de batata o decaimento do sinal apresentou excepcionalmente um comportamento linear quando a dose utilizada foi de 20 kGy. Foi obtido de maneira experimental o valor do fator g, que variou de 2,06062 a 1,94661, sendo o valor teórico g = 2,0023. Foram também estabelecidas as modificações radioinduzidas na estrutura molecular das amostras através da análise dos espectros de absorção no infravermelho por FTIR.
Title in English
Electronic paramagnetic resonance and infrared spectroscopy applied in the study of irradiated starches
Keywords in English
EPR
FITR
gamma radiation
starch
Abstract in English
Starch is the most abundant plant energy storage polysaccharide, usually deposited in the form of granules in the cytoplasm of cells. It is also the main source of energy for man, making up 80-90% of polysaccharides in the human diet, and is mainly responsible for the technological properties that characterize most processed products. The present work aimed to the application of electronic paramagnetic resonance and Fourier Transform Infrared Spectroscopy to the study of irradiated starches. Powdered samples of two natural starches, potato (bulb) and corn (cereal) and fermented cassava flour or sour cassava (root) were subjected to the action of ionizing radiation from a 60Co Gammacell 220 at doses of 10, 20 and 30 kGy, dose rate of 1kGy h-1. The electronic paramagnetic resonance spectra of the three types of irradiated and non-irradiated starches were recorded and compared. The starches showed similar electronic paramagnetic resonance spectra varying only in the intensity of the free radical signal that accompanied the dose increase. The decay curves were established for each of the tested starches. In the case of potato starch, signal decay showed an exceptionally linear behavior when the dose used was 20 kGy. The value of factor g was obtained experimentally, ranging from 2.06062 to 1.94661, with the theoretical value g = 2.0023. The radioinduced modifications in the molecular structure of the samples were also established by the analysis of the infrared absorption spectra by Fourier Transform Infrared Spectroscopy.
 
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Publishing Date
2017-12-05
 
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