Physiological and biochemical characteristics of four dominant microbes and content of yellow pigment in fermentation process of Pinelliae Rhizoma Fermentata / 中草药

Objective: To study the physiological and biochemical characteristics of four dominant microorganisms and the yellow pigment content of Pinelliae Rhizoma Fermentata (PRF), and provide basis for exploring the mechanism of PRF processing. Methods: The optimum growth temperature and pH value of the four dominant microorganisms Bacillus subtilis, Paecilomyces variotii, Byssochlamys spectabilis, and Aspergillus niger were studied. The ability of producing acidase, amylase, protease, and yellow pigment were determined. The yellow pigment content of each sample at different fermentation time points in process of PRF was determined. Results: The most suitable growth temperatures for B. subtilis, P. variotii, B. spectabilis, and A. niger were 35 ℃, 29 ℃, 29-31 ℃, and 39 ℃; And the optimum pH were 7.0, 7.0, 7.5, and 7.0, respectively. Four kinds of microorganisms had the ability to produce amylase and protease. P. variotii and B. spectabilis had the ability to produce yellow pigment. The content of yellow pigment were 69.875, 69.875, 71.750, 119.500, and 137.875 μg/g in the samples at different time points. Conclusion: Four kinds of dominant microorganisms may play an important role in fermentation process of PRF.

Growth of Byssochlamys nivea in pineapple juice under the effect of water activity and ascospore age

The study of thermal resistant mould, including Byssochlamys nivea, is of extreme importance since it has been associated with fruit and fruit products. The aim of this work is to analyze the influence of water activity (a w) and ascospore age (I) on the growth of Byssochlamys nivea in pineapple juice. Mold growth was carried out under different conditions of water activity (a w) (0.99, 0.96, 0.95, 0.93, 0.90) and ascospore age (I) (30, 51, 60, 69, 90 days). Growth parameters as length of adaptation phase (λ), maximum specific growth rate (µmax) and maximum diameter reached by the colony (λ) were obtained through the fit of the Modified Gompertz model to experimental data (measuring radial colony diameter). Statistica 6.0 was used for statistical analyses (significance level α = 0.05). The results obtained clearly showed that water activity is statistically significant and that it influences all growth parameters, while ascospore age does not have any statistically significant influence on growth parameters. Also, these data showed that by increasing a w from 0.90 to 0.99, the λ value substantially decreased, while µmax and λ values rose. The data contributed for the understanding of the behavior of B. nivea in pineapple juice. Therefore, it provided mathematical models that can well predict growth parameters, also helping on microbiological control and products' shelf life determination.

Efeito in vitro de concentrações de metabisulfito de sódio, benzoato de sódio e sorbato de potássio sobre fungos termorresistentes / In vitro effect of concentrations of sodium metabisulphite, sodium benzoate and potassium sorbate on heat-resistant fungi

Os fungos termorresistentes dos gêneros Byssochlamys, Neosartorya e Talaromyces representam grave problema para a indústria processadora de alimentos, especialmente de frutas e hortaliças, em virtude da ocorrência de ascosporos extremamente resistentes e/ou de micotoxinas termo estáveis. Com o propósito de fornecer subsídios quanto ao uso de quantidades mais racionais de conservantes pela indústria de alimentos e, portanto, tornar seu consumo menos danoso à população, o presente estudo determinou in vitro a concentração mínima de metabissulfito de sódio, benzoato de sódio e sorbato de potássio necessária e suficiente para inibir o crescimento micelial e a germinação de ascósporos de B. fulva, N. fischeri e T.flavus em meio de cultivo acidificado (pH 3,5). Foi demonstrado que metabissulfito de sódio em baixas concentrações é tão eficiente na inibição dos fungos mencionados quanto aos demais conservantes em altas concentrações. Por comparação com os procedimentos utilizados pelas indústrias de alimentos, é possível inferir que estas podem reformular o uso de conservantes, considerando-se o tipo de matéria-prima, a temperatura de processamento, a combinação e concentração efetivamente necessária de aditivos, bem como os efeitos tóxicos desses compostos para a saúde humana.