Métodos de extração e caracterização de bixina e norbixina em sementes de urucum (Bixa orellana L.)

• Ano de defesa: 2007
• Autor(a) principal: Silva, Pollyanna Ibrahim
• Orientador(a): Stringheta, Paulo César
• Banca de defesa: Otoni, Wagner Campos , Chauca, Milton Nobel Cano , Gloria, Maria Beatriz Abreu
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Ciência e Tecnologia de Alimentos
• Departamento: Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos
• País: BR
• Palavras-chave em Português: Corantes; Extração (Química); Urucum; Bixina; Norbixina
• Palavras-chave em Inglês: Colorants; Extraction (Chemistry); Annatto seeds; Bixin; Norbixin
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/2951

This research aimed to determine the best solvents in the extraction of annatto pigments, and the production methods of powdered and pasty colorants. In addition, methods for identification, quantification and isolation of these pigments were evaluated, as well as the factors that influence in the saponification reaction of bixin to form norbixin and its salt. In the evaluation of extraction solvents, the aqueous solutions of KOH 0,1 N and NH4OH 0,5 N, and the solutions of NH4OH 0,5 N in ethanol 60% and commercial ethanol were used. The extracts obtained by the solvents KOH 0,1 N and NH4OH 0,5 N were submitted to spray-drying, yielding powdered colorants. Those obtained by NH4OH 0,5N in ethanol 60% and by commercial ethanol were dried in a tray dehydrator, yielding pasty colorants. The extracts and the concentrated colorants were characterized for pH, moisture content, total solids, bixin and/or norbixin, ash, ammonia, potassium and colorimetry by the analysis of the coordinates L* , a* and b* . The colorants were submitted to identification techniques, as the infrared spectrometry, UV/Visible spectrophotometry and HPLC, in order to determine the profile of the present pigments. These pigments were quantified through spectrophotometry and HPLC. Bixin and norbixin standards of high purity degree were produced, based in methods already existent in the literature. In the analysis of the factors that influence in the saponification reaction of bixin to form norbixin and its salt, experiments were developed in order to evaluate the influence of: (i) extraction time when using the solvents KOH 0,1 N and NH4OH 0,5 N, at room temperature, from 30 minutes to 24 hours; (ii) extraction time and of solvents concentration when using KOH and NH4OH at 1%, 2%, 3%, 4% and 5%, during one and two hours of extraction; (iii) extraction time at 70 ºC, when using KOH 0,1 N and NH4OH 0,5 N, during one and two hours of extraction; (iv) different extraction temperatures, when using KOH 4% at 25, 50, 60 and 70 ºC, during one hour. The samples were analyzed by means of HPLC and spectrophotometry. The results indicated, in the evaluation of extraction solvents, that the most efficient solvent was NH4OH 0,5 N in ethanol 60%, yielding the smallest content of residual pigments in the seeds. The commercial ethanol was the solvent of smallest efficiency. For the pigment content in the extracts, commercial ethanol was also the solvent that showed smaller extraction power, while the other solvents showed similar performances. The different solvents had influence, also, in the increase of concentration of compounds present in the produced colorants, as ash, nitrogenated compounds or potassium. The colorimetric coordinates L* , a* and b* varied with pH, and with the type of extraction solvent. Through infrared spectrometry the presence of bixin in all colorants was verified. For bixin and norbixin isolation, new methodologies were developed. These methodologies, when compared to the traditional ones, were lower-cost and more efficient. By means of HPLC, bixin was the major component from extraction of annatto pigments, when using both the aqueous alkaline and the alcoholic solvents. In the analysis of the factors that influence in the saponification reaction of bixin to form norbixin and its salt, to the alkali NH4OH, the extraction time was the factor that most had influence. To the alkali KOH, the concentration and the extraction temperature were the factors that most influenced in the bixin hydrolysis. Both spectrophotometry and HPLC techniques for quantification of annatto pigments gave satisfactory results.