Obtenção e avaliação de extratos de erva mate (Ilex paraguariensis) fermentados com a cultura simbiótica kombucha
Resumo
A kombucha é uma bebida de sabor ácido e adocicado, obtida através da fermentação do chá
preto ou verde adoçado. A fermentação é realizada por uma cultura simbiótica de bactérias do
ácido acético e leveduras osmófilas, que utilizam a sacarose como fonte energética. Durante o
processo fermentativo são formados compostos, tais como vitaminas hidrossolúveis,
aminoácidos, ácidos orgânicos, álcool, entre outros, e há melhor biodisponibilidade dos
compostos bioativos e minerais presentes no chá. O teor desses compostos depende das
características do chá utilizado, temperatura e tempo de fermentação. A produção e comércio
da kombucha têm aumentado nos últimos anos devido aos benefícios a saúde conferidos a seu
consumo. No entanto, há necessidade de estudos para comprovar suas propriedades funcionais.
Em face disso, os objetivos deste trabalho foram obter kombucha de erva mate (Ilex
paraguariensis) utilizando a cultura simbiótica de bactérias e leveduras da kombucha como
inóculo e avaliar suas características físico-químicas e biológicas. Foram utilizados extratos de
erva mate na concentração de 0,5%, 0,75% e 1% e as temperaturas de fermentação de 20, 25 e
30 ºC em um delineamento composto central com 3 repetições no ponto central após 12 dias de
fermentação, tendo como resposta a concentração de compostos fenólicos totais e a atividade
antioxidante. Para obtenção da bebida, o meio de cultivo foi preparado contendo infusão de
erva-mate, sacarose e com adição de kombucha fermentada anteriormente. Durante a
fermentação, foram retiradas amostras para medição de açúcares redutores totais, pH,
compostos fenólicos totais e atividade antioxidante. Os açúcares foram quantificados pelo
método de 3,5-dinitrossalicílico, os compostos fenólicos totais foram determinados por método
de Folin-Ciocalteau, a atividade antioxidante foi determinada pelos métodos de capacidade de
sequestro do radical 2,2-difenil-1-picril-hidrazila (DPPH) e captura do radical 2,2-azinobus-3-
3etilbenzotiazolina-6-ácido-sulfônico (ABTS). Para a atividade antimicrobiana, foi medido o
diâmetro do halo de inibição utilizando os micro-organismos Escherichia coli e Staphylococcus
aureus e o estresse oxidativo in vivo foi analisado utilizando a levedura Saccharomyces
cerevisiae como modelo. A kombucha de erva mate fermentada por 12 d, apresentou pH entre
1,8±0,1 e 2,3±0,1; acidez de 4,83±0,06 a 6,03±0,06 g/L de ácido acético; açúcares redutores
totais entre 15,94±0,09 e 23,07±0,17 g/L; compostos fenólicos totais entre 444,23±3,50 e
844,78±1,13 mg/L equivalente ácido gálico. A atividade antioxidante calculada pelo método de
DPPH foi menos eficaz, recebendo incremento na capacidade de eliminação de radicais
inferiores a 5%. A atividade antioxidante da bebida foi determinada pelo método de ABTS,
apresentou aumento entre 16,16 e 31,34%. Os ensaios que apresentaram maiores conteúdos de
compostos fenólicos totais e atividade antioxidante foram utilizados na avaliação da atividade
antibacteriana e do estresse oxidativo. Os resultados mostraram que a kombucha de erva mate
apresentou atividade antibacteriana contra as cepas de S. aureus e E. coli. A kombucha de erva
mate também foi efetiva na prevenção do dano oxidativo induzido pelo peróxido de hidrogênio,
sendo que a adição de kombucha resultou em uma taxa de sobrevivência da levedura S.
cerevisiae de até 57,0%, sendo este valor superior ao encontrado na kombucha tradicional (chá
verde), que foi 43,5%.
Kombucha is an acid and sweet flavor drink, obtained through fermentation of sugared black or green tea. The fermentation process is undertaken by a symbiotic bacterial culture of acetic acid and osmophilic yeasts, which use sucrose as energetic source. During fermentative process, some compounds are formed, including hydrosoluble vitamins, amino acids, organic acids, alcohol, among others, improving the biodisponibility of bioactive compounds and minerals present in the tea. The content of these compounds depends on characteristics of the selected tea, temperature and time of fermentation. The production and commerce of kombucha have been increasing in the last years due the benefits to health attributed to its consumption, although more studies proving its functional properties are necessary. Therefore, the objectives of this work were to obtain the drink from mate herb (Ilex paraguariensis) fermented by symbiotic bacterial culture and yeasts of kombucha, and to evaluate its physical-chemical and biological characteristics. For this work, extracts of mate herb were used in the concentrations of 0.5%, 0.75% and 1% and the fermentation temperatures of 20, 25 and 30ºC in an experimental delimitation with three repetitions at the central point after 12 days of fermentation, having as response the concentration of total phenolic compounds and the antioxidant activity. For obtainment of the drink, the culture medium was prepared containing mate herb infusion, sucrose and with addition of previously fermented kombucha. During the fermentation process, samples were isolated for measurement of total reducing sugars, pH, total phenolic compounds and antioxidant activity. The sugars were quantified by the 3,5- dinitrosalicylic method, the total phenolic compounds were determined by Folin-Ciocalteau method, the antioxidant activity was determined by methods of sequestration capacity of 2,2- diphenyl-1-picrylhydrazyl (DPPH) and the capture of radical 2,2’-azino-bis-3- ethylbenzthiazoline-6-sulphonic acid (ABTS). For antimicrobial activity, the inhibition zone was measured using the micro-organisms Escherichia coli and Staphylococcus aureus, and the oxidative stress in vivo was analyzed using the yeast Saccharomyces cerevisiae as model. The mate herb kombucha fermented for 12 days presented pH between 1.8±0.1 and 2.3±0.1; acidity of 4.83±0.06 to 6.03±0.06 g/L of acetic acid; total reducing sugars between 15.94±0.09 and 23.07±0.17 g/L; total phenolic compounds between 444.23±3.50 and 844.78±1.13 mg/L equivalent to gallic acid. The antioxidant activity calculated by DPPH method was less effective, receiving increase in elimination capacity of radicals less than 5%. The antioxidant activity of the drink was determined by ABTS method, and presented increase between 16.16 and 31.34%. The essays which presented higher contents of total phenolic compounds and antioxidant activity were used in the evaluation of antibacterial activity and oxidative stress. The results showed that mate herb kombucha presented antibacterial activity against strains of S. aureus and E. coli. Mate herb kombucha was also effective in the prevention of oxidative damage induced by hydrogen peroxide, since the addition of kombucha resulted in a surviving rate of the yeast S. cerevisiae of until 57%, being this value higher than that found in traditional kombucha (green tea), which was 43.5%.
Kombucha is an acid and sweet flavor drink, obtained through fermentation of sugared black or green tea. The fermentation process is undertaken by a symbiotic bacterial culture of acetic acid and osmophilic yeasts, which use sucrose as energetic source. During fermentative process, some compounds are formed, including hydrosoluble vitamins, amino acids, organic acids, alcohol, among others, improving the biodisponibility of bioactive compounds and minerals present in the tea. The content of these compounds depends on characteristics of the selected tea, temperature and time of fermentation. The production and commerce of kombucha have been increasing in the last years due the benefits to health attributed to its consumption, although more studies proving its functional properties are necessary. Therefore, the objectives of this work were to obtain the drink from mate herb (Ilex paraguariensis) fermented by symbiotic bacterial culture and yeasts of kombucha, and to evaluate its physical-chemical and biological characteristics. For this work, extracts of mate herb were used in the concentrations of 0.5%, 0.75% and 1% and the fermentation temperatures of 20, 25 and 30ºC in an experimental delimitation with three repetitions at the central point after 12 days of fermentation, having as response the concentration of total phenolic compounds and the antioxidant activity. For obtainment of the drink, the culture medium was prepared containing mate herb infusion, sucrose and with addition of previously fermented kombucha. During the fermentation process, samples were isolated for measurement of total reducing sugars, pH, total phenolic compounds and antioxidant activity. The sugars were quantified by the 3,5- dinitrosalicylic method, the total phenolic compounds were determined by Folin-Ciocalteau method, the antioxidant activity was determined by methods of sequestration capacity of 2,2- diphenyl-1-picrylhydrazyl (DPPH) and the capture of radical 2,2’-azino-bis-3- ethylbenzthiazoline-6-sulphonic acid (ABTS). For antimicrobial activity, the inhibition zone was measured using the micro-organisms Escherichia coli and Staphylococcus aureus, and the oxidative stress in vivo was analyzed using the yeast Saccharomyces cerevisiae as model. The mate herb kombucha fermented for 12 days presented pH between 1.8±0.1 and 2.3±0.1; acidity of 4.83±0.06 to 6.03±0.06 g/L of acetic acid; total reducing sugars between 15.94±0.09 and 23.07±0.17 g/L; total phenolic compounds between 444.23±3.50 and 844.78±1.13 mg/L equivalent to gallic acid. The antioxidant activity calculated by DPPH method was less effective, receiving increase in elimination capacity of radicals less than 5%. The antioxidant activity of the drink was determined by ABTS method, and presented increase between 16.16 and 31.34%. The essays which presented higher contents of total phenolic compounds and antioxidant activity were used in the evaluation of antibacterial activity and oxidative stress. The results showed that mate herb kombucha presented antibacterial activity against strains of S. aureus and E. coli. Mate herb kombucha was also effective in the prevention of oxidative damage induced by hydrogen peroxide, since the addition of kombucha resulted in a surviving rate of the yeast S. cerevisiae of until 57%, being this value higher than that found in traditional kombucha (green tea), which was 43.5%.
Descrição
Dissertação (Mestrado)
Palavras-chave
Bebida funcional, Antibacteriano, Chá fermentado, Bioatividade, Erva mate, Estresse oxidativo, Functional beverage, Antibacterial, Bioactivity, Fermented tea, Mate herb, Oxidative stress
Citação
LOPES, Danielle Rubim. Obtenção e avaliação de extratos de erva mate (Ilex paraguariensis) fermentados com a cultura simbiótica kombucha. 2019. 94 f. Dissertação (Mestrado em Engenharia e Ciência de Alimentos) - Programa de Pós-graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, Universidade Federal do Rio Grande, Rio Grande, 2019.