Orientador : Paulo Anna Bobbio

Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos e Agrícola

Resumo: Foram preparadas melanoidinas usando-se frutose nas concentrações 1,25 e 2,50 M e glicina 0,66 e 1,32 M, nos pH 3,0 e 6,0 e nas temperaturas 70,0, 80,0 e 90,0ºC. As melanoidinas obtidas a pH 3,0, insolúveis em água, foram isoladas por filtração e aquelas a pH 6,0, solúveis, por diálise...

Resumo: Foram preparadas melanoidinas usando-se frutose nas concentrações 1,25 e 2,50 M e glicina 0,66 e 1,32 M, nos pH 3,0 e 6,0 e nas temperaturas 70,0, 80,0 e 90,0ºC. As melanoidinas obtidas a pH 3,0, insolúveis em água, foram isoladas por filtração e aquelas a pH 6,0, solúveis, por diálise através de uma membrana de celofane. Dos produtos purificados foram feitas as análises elementares e obtido os espectros infravermelho. Nas melanoidinas solúveis foram determinados os pesos moleculares e os grupos presentes na molécula. Esses dados aliados a identificação de alguns produtos da degradação oxidativa permitiram sugerir algumas estruturas características, a saber: cetona e álcool a, ß-insaturados, ß-e ?-dicetonas e diálcoois e ß-e ?-hidroxicetona

Abstract: Melanoidins were prepared using 1.25 and 2.50 M fructose, and 0.66 and 1.32 M glycine at pH's of 3.0, and 6.0 and at temperatures of 70.0, 80.0, and 90.0ºC. The melanoidins obtained at pH 3.0 were unsoluble in water and were isolated by fi1tration. Those obtained at pH 6.0 were water...

Abstract: Melanoidins were prepared using 1.25 and 2.50 M fructose, and 0.66 and 1.32 M glycine at pH's of 3.0, and 6.0 and at temperatures of 70.0, 80.0, and 90.0ºC. The melanoidins obtained at pH 3.0 were unsoluble in water and were isolated by fi1tration. Those obtained at pH 6.0 were water soluble and were purified by dialysis using a cellophane membrane. Infrared spectra and elementary analysis were obtained for the isolated melanoidins. The functional groups and the molecular weights of the soluble melanoidins were determined. These collected data, together with the products identified from oxidative degradation led to suggestions of some possible structures for soluble melanoidins. The structures proposed are:a, ß-unsaturated ketone and alcohol, ß- and ?-diketones and dialcohols, and ß- and ?-hydroxy-ketones