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Propriedades microbiológicas e físico-químicas de produtos acetificados obtidos de frutos fermentados
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Abstract(s)
O presente trabalho teve como objetivo estudar as caraterísticas de produtos acetificados, nomeadamente de vinagres dos frutos fermentados ameixa e framboesa, e ainda de cerveja e gengibre. Estes produtos foram processados pelo método de Orleans e engarrafados numa empresa do Algarve. Procedeu-se à sua caracterização físico-química (pH, acidez total, °Brix, cor, teor de compostos fenólicos e flavonoides, e atividade antioxidante) e microbiológica (contagens de microrganismos mesófilos, bactérias ácido-láticas, fungos filamentosos, leveduras e bactérias acéticas). Estudou-se ainda a atividade antimicrobiana dos vinagres contra bactérias e leveduras utilizando o método da difusão em agar. O vinagre de framboesa foi o que apresentou valores mais elevados de pH (3,30), acidez (6,82±0,06 g/100 ml), e compostos flavonoides (161,64±11,25 mg catequina/100 ml). O vinagre de ameixa possuía o nível mais baixo de acidez (5,25±0,17 g/100 ml) e o de gengibre menores quantidades de compostos fenólicos (0,25±0,01 mg ácido gálico/100 ml) e flavonoides (50,73±12,54 mg catequina/100 ml). A atividade antioxidante mais alta foi detetada no vinagre de framboesa (0,28±0,02 DPPH, mg Trolox/100 ml) seguida do de cerveja (0,04±0,00 DPPH, mg Trolox/100 ml) que apresentou o maior conteúdo em compostos fenólicos (0,62±0,06 mg ácido gálico/100 ml) e pH menor (2,77±0,03). As amostras estudadas apresentaram uma elevada qualidade microbiológica pois as contagens realizadas estavam todas abaixo de 1 UFC/ml. Os vinagres revelaram uma capacidade de inibição do crescimento das bactérias superior à detetada nas leveduras. O crescimento das leveduras, Candida albicans, Saccharomyces cerevisiae e Zygosaccharomyces bailii, não foi inibido pelos vinagres estudados. As enterobactérias Cronobacter sakazakii e Salmonella Typhimurium foram as mais tolerantes aos vinagres (10,00±0,00 - 17,33±4,18 mm), enquanto Pseudomonas aeruginosa foi a bactéria mais sensível (28,40±3,21 - 39,00±1,00 mm) assim como as Gram + (Staphylococcus aureus, Listeria innocua, Staphylococcus epidermidis) (23,80±2,39-30,50±1,00 mm). A maior atividade antimicrobiana foi detetada nos vinagres de framboesa e gengibre provavelmente devido à elevada acidez.
The present work aimed to study the characteristics of acetified products, namely vinegars of fermented plum and raspberry fruits, as well as beer and ginger. These products were processed by the Orleans method and bottled in a company in the Algarve. Physicochemical characterization (pH, total acidity, °Brix, color, content of phenolic and flavonoid compounds, and antioxidant activity) and microbiological (counts of mesophilic microorganisms, lactic acid bacteria, filamentous fungi, yeasts and acetic bacteria) were performed. The antimicrobial activity of vinegars against bacteria and yeasts was also studied using the agar diffusion method. Raspberry vinegar had the highest values in pH (3.30), acidity (6.82±0.06 g/100 ml), and flavonoid compounds (161.64±11.25 mg catechin/100 ml). Plum vinegar had the lowest level of acetic acid (5.25±0.17 g/100 ml) and ginger vinegar was characterized by having smaller amounts of phenolic compounds (0.25±0.01 mg gallic acid/100 ml) and flavonoids (50.73±12.54 mg catechin/100 ml). The highest antioxidant activity was detected in raspberry vinegar (0.28±0.02 DPPH, mg Trolox/100 ml) followed by beer (0.04±0.00 DPPH, mg Trolox/100 ml) which presented the highest content of phenolic compounds (0.62±0.06 mg gallic acid/100 ml) and lower pH (2.77±0.03). The samples showed a high microbiological quality since the microbial counts performed were all below 1 CFU/ml. The vinegars showed an ability to inhibit the growth of bacteria superior to that measured in yeasts. Some yeasts namely a strain of Candida albicans, Saccharomyces cerevisiae and Zygosaccharomyces bailii, were not inhibited by the vinegars. The enterobacteria Cronobacter sakazakii and Salmonella Typhimurium were the most tolerant (10.00±0.00 - 17.33±4.18mm), while Pseudomonas aeruginosa was the most sensitive bacteria (28.40±3.21 - 39.00±1.00 mm) as well as Gram + (Staphylococcus aureus, Listeria innocua, Staphylococcus epidermidis) (23.80±2.39-30.50±1.00 mm). Raspberry and ginger vinegars induced the greatest antimicrobial activity which may be related to the high acidity content.
The present work aimed to study the characteristics of acetified products, namely vinegars of fermented plum and raspberry fruits, as well as beer and ginger. These products were processed by the Orleans method and bottled in a company in the Algarve. Physicochemical characterization (pH, total acidity, °Brix, color, content of phenolic and flavonoid compounds, and antioxidant activity) and microbiological (counts of mesophilic microorganisms, lactic acid bacteria, filamentous fungi, yeasts and acetic bacteria) were performed. The antimicrobial activity of vinegars against bacteria and yeasts was also studied using the agar diffusion method. Raspberry vinegar had the highest values in pH (3.30), acidity (6.82±0.06 g/100 ml), and flavonoid compounds (161.64±11.25 mg catechin/100 ml). Plum vinegar had the lowest level of acetic acid (5.25±0.17 g/100 ml) and ginger vinegar was characterized by having smaller amounts of phenolic compounds (0.25±0.01 mg gallic acid/100 ml) and flavonoids (50.73±12.54 mg catechin/100 ml). The highest antioxidant activity was detected in raspberry vinegar (0.28±0.02 DPPH, mg Trolox/100 ml) followed by beer (0.04±0.00 DPPH, mg Trolox/100 ml) which presented the highest content of phenolic compounds (0.62±0.06 mg gallic acid/100 ml) and lower pH (2.77±0.03). The samples showed a high microbiological quality since the microbial counts performed were all below 1 CFU/ml. The vinegars showed an ability to inhibit the growth of bacteria superior to that measured in yeasts. Some yeasts namely a strain of Candida albicans, Saccharomyces cerevisiae and Zygosaccharomyces bailii, were not inhibited by the vinegars. The enterobacteria Cronobacter sakazakii and Salmonella Typhimurium were the most tolerant (10.00±0.00 - 17.33±4.18mm), while Pseudomonas aeruginosa was the most sensitive bacteria (28.40±3.21 - 39.00±1.00 mm) as well as Gram + (Staphylococcus aureus, Listeria innocua, Staphylococcus epidermidis) (23.80±2.39-30.50±1.00 mm). Raspberry and ginger vinegars induced the greatest antimicrobial activity which may be related to the high acidity content.
Description
Keywords
Produtos acetificados Vinagre Parâmetros físico-químicos e microbiológicos Atividade antioxidante Atividade antimicrobiana