Avaliação da liofilização para produção de criogéis como material de parede e sua aplicação em encapsulação de betalaínas
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Data
2019-04-25
Autores
Chaux-Gutiérrez, Ana María
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho foi abordado o estudo da albumina de ovo (ALB) e sua mistura com pectina amidada de baixa metoxilação (PEC) como material de parede na encapsulação de betalaína. Inicialmente, foram caracterizados os géis de ALB e dos produzidos usando a mistura de albumina com diferentes proporções de PEC (1, 2, 2,5, 3 e 4 %) (ALB-PEC), a pH 8 e sem ajuste de pH. A caracterização estrutural e as interações na matriz foram feitas através das análises do potencial zeta, testes reológicos, espectroscopia de infravermelho e microscopia confocal. Resultados de ensaios oscilatórios indicaram que a estrutura formada pelos biopolímeros apresentou características de um gel fraco e foram dependentes da frequência. As interações do tipo repulsão eletrostática, observadas entre a albumina e a pectina nas concentrações 1 % e 2 %, provocaram um aumento no módulo de armazenamento (G’), no entanto, concentrações acima de 2 % ocasionaram diminuição no valor de G’ e a agregação da albumina na matriz. Numa segunda etapa do estudo, foram preparados criogéis usando a betalaína como composto bioativo de interesse, sendo que o material de parede foi formulado somente com ALB e com ALB-PEC usando 1 %, 2 % e 2,5 % de PEC. Para a incorporação da betalaína foram propostas e avaliadas duas metodologias, chamadas de précarga e pós-carga. As interações e as características morfológicas foram analisadas por espectrofotometria UV-visível, infravermelho (FTIR), determinação de área superficial específica (BET) e microscopia eletrônica de varredura (MEV). De acordo com os resultados, foram encontrados altos valores de eficiência de encapsulação (88-97 %) independentemente da concentração de pectina e da metodologia usada na incorporação da betalaína. Da análise dos espectros de FTIR foi estabelecida a ocorrência de interações entre a betalaína, a ALB e a PEC. O perfil de liberação da betalaína dos criogéis de ALB e ALB-PEC indicou que existe um efeito significativo da concentração de PEC e da metodologia de incorporação da betalaína na liberação a diferentes condições de pH. A análise morfológica indicou que o criogel de ALB apresentou uma estrutura mais compacta, enquanto que os criogéis de ALBPEC apresentaram estrutura mais porosa. Finalmente, foi avaliada a estabilidade da betalaína durante o armazenamento em duas umidades relativas, 32 e 83 % nas temperaturas de 4 °C, 30 °C e 40 °C. Para essas análises, foram selecionados os criogéis de ALB e de ALB-PEC (1 % PEC) usando a metodologia de pré-carga. A retenção da betalaína (betanina + isobetanina) e dos compostos fenólicos, assim como a atividade antioxidante foi determinada mediante cromatografia líquida (HPLC), pelo método de Folin-Ciocalteu e pela captura do radical ABTS*+, respectivamente e os parâmetros de cor espectrofotometricamente. O criogel de ALB permitiu manter altas retenções da betanina e isobetanina (72 % e 82 %) a 32 % UR e 4 °C, assim como tempos de meia-vida de 108 dias e 165 dias, respectivamente, e também proporcionou altas retenções de atividade antioxidante (90-93 %) e de compostos fenólicos (84-90 %) durante o armazenamento a 32 % UR, em todas as temperaturas. A retenção da betalaína foi drasticamente afetada pela umidade relativa de 83 % UR.
The thesis explores the capacity of egg albumen (ALB) and their mixture with low methoxyl amidated pectin (PEC) as a wall material for betalain encapsulation. Initially, ALB gels and those produced using the ALB and PEC mixture were characterized, at pH 8 and without pH adjustment. The structural characterization and the interactions between each component in the matrix were performed by using, zeta potential analysis, oscillatory rheological tests, FTIR spectrometry, and confocal microscopy. The oscillatory tests results indicated that the structure formed by the biopolymers had characteristics of a weak gel, and were frequency dependent. Results indicated that there was electrostatic repulsion between the albumin at 1 % and 2 % of pectin concentration, leading to an increase in storage modulus (G'), however, concentrations above 2 % caused a decrease in the G' value, and formation of electrostatic complexes, as well as the aggregation of albumin in the matrix. Additionally, cryogels with betalain as guest molecule were prepared using ALB and ALB-PEC mixture with 1 %, 2 % and 2.5 % of PEC. For the betalain inclusion, were proposed and evaluated two methodologies, which were called pre-loading and post-loading. The physicochemical interactions between betalain and wall material and morphological characteristics were analyzed by UV-vis spectrophotometry, FT-IR spectrophotometry, specific surface area determination (BET), and scanning electron microscopy (SEM). Also, encapsulation efficiency and their delivery profile were analyzed. Criogels showed high encapsulation efficiency (88-97%) regardless of pectin concentration and the betalain inclusion methodology. Results of FT-IR indicated that there was an interaction among ALB, PEC and betalain. The betalain delivery patterns were affected by PEC content and inclusion methodology at different pH conditions. The morphological analysis indicates that ALB cryogel has a more compact structure, whereas, ALB-PEC cryogel showed a more porous structure. Finally, betalains stability in ALB and ALB-PEC cryogels (1 % PEC), using the pre-loading methodology, was evaluated during storage at two relative humidities (32 and 83 % RH), at 4 °C, 30 °C and 40 °C. Betalains (betanin + isobetanin) and phenolic compounds retention, as well as antioxidant activity and color parameters were determined by highperformance liquid chromatography (HPLC), Folin-Ciocalteu method, and radical capture of ABTS*+. ALB cryogel had high betanin and isobetanin retention (72 % and 82 %) during the storage time at 32 % RH and 4 ° C, as well as half-lives were 108 and 165 days, respectively, and even high retention of antioxidant activity (90-93 %) and phenolic compounds content (84-90 %) were obtained at all storage temperatures at 32 % RH. The betalain retention was highly affected by the relative humidity of 83 % RH.
The thesis explores the capacity of egg albumen (ALB) and their mixture with low methoxyl amidated pectin (PEC) as a wall material for betalain encapsulation. Initially, ALB gels and those produced using the ALB and PEC mixture were characterized, at pH 8 and without pH adjustment. The structural characterization and the interactions between each component in the matrix were performed by using, zeta potential analysis, oscillatory rheological tests, FTIR spectrometry, and confocal microscopy. The oscillatory tests results indicated that the structure formed by the biopolymers had characteristics of a weak gel, and were frequency dependent. Results indicated that there was electrostatic repulsion between the albumin at 1 % and 2 % of pectin concentration, leading to an increase in storage modulus (G'), however, concentrations above 2 % caused a decrease in the G' value, and formation of electrostatic complexes, as well as the aggregation of albumin in the matrix. Additionally, cryogels with betalain as guest molecule were prepared using ALB and ALB-PEC mixture with 1 %, 2 % and 2.5 % of PEC. For the betalain inclusion, were proposed and evaluated two methodologies, which were called pre-loading and post-loading. The physicochemical interactions between betalain and wall material and morphological characteristics were analyzed by UV-vis spectrophotometry, FT-IR spectrophotometry, specific surface area determination (BET), and scanning electron microscopy (SEM). Also, encapsulation efficiency and their delivery profile were analyzed. Criogels showed high encapsulation efficiency (88-97%) regardless of pectin concentration and the betalain inclusion methodology. Results of FT-IR indicated that there was an interaction among ALB, PEC and betalain. The betalain delivery patterns were affected by PEC content and inclusion methodology at different pH conditions. The morphological analysis indicates that ALB cryogel has a more compact structure, whereas, ALB-PEC cryogel showed a more porous structure. Finally, betalains stability in ALB and ALB-PEC cryogels (1 % PEC), using the pre-loading methodology, was evaluated during storage at two relative humidities (32 and 83 % RH), at 4 °C, 30 °C and 40 °C. Betalains (betanin + isobetanin) and phenolic compounds retention, as well as antioxidant activity and color parameters were determined by highperformance liquid chromatography (HPLC), Folin-Ciocalteu method, and radical capture of ABTS*+. ALB cryogel had high betanin and isobetanin retention (72 % and 82 %) during the storage time at 32 % RH and 4 ° C, as well as half-lives were 108 and 165 days, respectively, and even high retention of antioxidant activity (90-93 %) and phenolic compounds content (84-90 %) were obtained at all storage temperatures at 32 % RH. The betalain retention was highly affected by the relative humidity of 83 % RH.
Descrição
Palavras-chave
Albumina, Pectina amidada, Isobetanina, Cinética de degradação, Microestrutura, Beterraba, Albumin, Amidated pectin, Isobetanin, Kinetics of degradation, Microstructure, Beetroot