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Abstract(s)
Os corantes são usados na indústria alimentar, química e farmacêutica, entre outras, para conferir cor, com o objetivo de tornar o produto mais atraente para os consumidores. Adicionalmente, nos últimos anos, a procura por produtos naturais seguros tem incrementado, devido à preocupação crescente dos consumidores pela adoção de um estilo de vida mais saudável. No caso concreto dos corantes, esta tendência resulta, principalmente, da imposição de doses máximas de utilização de alguns corantes sintéticos devido aos efeitos derivados do seu consumo excessivo. No entanto, do ponto de vista da aplicação, os corantes naturais apresentam algumas restrições, estando estas principalmente relacionadas com a instabilidade ao pH e temperatura. Uma das estratégias possíveis para aumentar a estabilidade e viabilizar o seu uso mais generalizado consiste na utilização de técnicas de microencapsulação ou emulsificação. Assim, o presente trabalho teve como principal objetivo estabilizar um corante natural hidrofílico baseado em antocianinas (Sambucus nigra L.) através da preparação de emulsões duplas (água/óleo/água). Com este tipo de estratégia pretendeu-se conseguir uma maior estabilidade do corante a variações de pH. Primeiramente fez-se a caracterização do extrato quanto à estabilidade da cor ao pH, temperatura (análise termogravimétrica (TGA/DTG)) e análise estrutural (Espectrocopia de Infravermelho com Transformada de Fourier (FTIR)). Posteriormente, procedeu-se à otimização da preparação da emulsão dupla, afim de obter uma formulação estável, testando diferentes variáveis como a razão água/óleo da emulsão primária, razão emulsão primária/água, sistemas emulsionantes e energia mecânica aplicada. As emulsões duplas obtidas foram avaliadas quanto à estabilidade e morfologia e capacidade corante ao longo do tempo (teste efetuado com soluções tampão na gama de pH 4-9). Face aos resultados obtidos escolheu-se a emulsão mais promissora (50/50) que foi testada em matrizes alimentares de diferentes pHs como o iogurte (pH 4,65), bebida de arroz (pH 6,01), leite (pH 6,47) e bebida de soja (pH 7,92). Estas foram observadas visualmente e caracterizadas por análise colorimétrica e comparadas com a incorporação direta do extrato livre ao longo do armazenamento (0, 3 e 7 dias). Em síntese, a dupla emulsão incorporando extrato de Sambucus nigra L. e produzida com uma razão 50/50 (emulsão primária/ fase aquosa externa) mostrou-se capaz de proteger o corante em meios ácidos e básicos, confirmando o interesse da abordagem proposta neste trabalho no campo do desenvolvimento de formulações corantes baseadas em corantes naturais. Adicionalmente, foi obtida uma coloração mais uniforme em função do pH.
Colorants are used in the food, chemical and pharmaceutical industries, among others, to impart color and increase product’s attractiveness to consumers. Moreover, in recent years the demand for safe natural products has increased partly due to the growing concern to adopt a healthier lifestyle. In the case of colorants, this trend derives mainly from the imposition of the maximum intake doses allowed for some synthetic colorants, due to the effects resulting from their excessive consumption. However, from the point of view of the application, the natural colorants present some constraints, these being mainly related with the instability under certain pH and temperature conditions. One of the possible strategies to increase the stability of these colorants, and ensure their generalized application, is the use of microencapsulation or emulsion techniques. Thus, the main objective of the present work is to stabilize a natural hydrophilic colorant based on anthocyanins (Sambucus nigra L.) through the preparation of double emulsions (water/oil/water). This strategy is intended to ensure protection against pH modifications. Firstly, the extract was characterized regarding pH stability, temperature (thermogravimetric analysis (TG/DTA)) and structural analysis (Fourier Transform Infrared spectroscopy (FTIR)). Subsequently, the preparation of the double emulsion was optimized in order to obtain a stable formulation, testing different variables such as the water/oil ratio of the primary emulsion, primary emulsion/water ratio, emulsification systems and applied mechanical energy were tested. The obtained double emulsions were evaluated regarding stability, morphology and coloring power through time (test done with buffer solution in the pH range of 4-9). Following these tests, the most promising emulsion (50/50) was chosen and tested in multiple food matrices with different pHs, such as yogurt (pH 4.65), rice drink (pH 6.01), milk (pH 6.47) and soy drink (pH 7.92). These food matrices were observed visually and characterized by colorimetric analysis, then compared with the direct incorporation of the extract during storage (0, 3 and 7 days). Summarizing, the double emulsion incorporating the extract of Sambucus nigra L. and produced with the 50/50 ratio (primary emulsion/extern aqueous phase) showed to be capable of protecting the colorant in acid and basic media, confirming the interest of the proposed approach in the field of natural formulation colorants. Moreover an increased color uniformity as a function of pH was achieved.
Colorants are used in the food, chemical and pharmaceutical industries, among others, to impart color and increase product’s attractiveness to consumers. Moreover, in recent years the demand for safe natural products has increased partly due to the growing concern to adopt a healthier lifestyle. In the case of colorants, this trend derives mainly from the imposition of the maximum intake doses allowed for some synthetic colorants, due to the effects resulting from their excessive consumption. However, from the point of view of the application, the natural colorants present some constraints, these being mainly related with the instability under certain pH and temperature conditions. One of the possible strategies to increase the stability of these colorants, and ensure their generalized application, is the use of microencapsulation or emulsion techniques. Thus, the main objective of the present work is to stabilize a natural hydrophilic colorant based on anthocyanins (Sambucus nigra L.) through the preparation of double emulsions (water/oil/water). This strategy is intended to ensure protection against pH modifications. Firstly, the extract was characterized regarding pH stability, temperature (thermogravimetric analysis (TG/DTA)) and structural analysis (Fourier Transform Infrared spectroscopy (FTIR)). Subsequently, the preparation of the double emulsion was optimized in order to obtain a stable formulation, testing different variables such as the water/oil ratio of the primary emulsion, primary emulsion/water ratio, emulsification systems and applied mechanical energy were tested. The obtained double emulsions were evaluated regarding stability, morphology and coloring power through time (test done with buffer solution in the pH range of 4-9). Following these tests, the most promising emulsion (50/50) was chosen and tested in multiple food matrices with different pHs, such as yogurt (pH 4.65), rice drink (pH 6.01), milk (pH 6.47) and soy drink (pH 7.92). These food matrices were observed visually and characterized by colorimetric analysis, then compared with the direct incorporation of the extract during storage (0, 3 and 7 days). Summarizing, the double emulsion incorporating the extract of Sambucus nigra L. and produced with the 50/50 ratio (primary emulsion/extern aqueous phase) showed to be capable of protecting the colorant in acid and basic media, confirming the interest of the proposed approach in the field of natural formulation colorants. Moreover an increased color uniformity as a function of pH was achieved.
Description
Dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Corantes naturais Sambucus nigra L. Estabilização ao pH Emulsões duplas Aplicações alimentares