Browsing by Subject "Microbial contamination"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Publication
    Open Access
    Ion mobility spectrometry and mass spectrometry coupled to gas chromatography for analysis of microbial contaminated cosmetic creams
    (Elsevier, 2020-07-11) García Nicolás, María; Arroyo Manzanares, Natalia; Hernández, Juan de Dios; Guillén, Isidro; Vizcaino, Pascuala; Sánchez Rubio, Marta; López García, Ignacio Francisco; Hernández Córdoba, Manuel; Viñas López-Pelegrin, Pilar; Química Analítica
    The most commonly used technique for monitoring microbial contamination in cosmetic products is plate counting. In this contribution, headspace - gas chromatography (HS-GC) coupled to mass spectrometry (MS) or ion mobility spectrometry (IMS) is proposed as a technique to evaluate rapidly and accurately the state of microbial colonies in cosmetic creams using the volatile organic compounds produced by microorganisms (MVOC). The work focuses on monitoring two of the microorganisms that most frequently occur in such creams, Candida albicans and Staphylococcus aureus. In addition, two different types of ingredient with antimicrobial properties (a chemical preservative and a natural preservative) were added to study the behaviour of these microorganisms under different conditions. The facial creams were elaborated and inoculated with the two above microorganisms, and then sampled weekly for 4 weeks, analysing the evolution of the MVOCs by HS-GC-MS and HS-GC-IMS. In addition, microbial contamination was determined by the classical plate counting method. The pH, colour, viscosity and water activity parameters were also measured. The use of chemometric tools is essential because of the large amount of data generated, and different models based on discriminant analysis with an orthogonal projection on latent structures (OPLS-DA) were constructed. The optimal models obtained by both analytical techniques allowed differentiation between contaminated and non-contaminated creams, with a validation success rate of 94.4%. In addition, MVOC monitoring also allowed assessment of the microbial concentration.
  • Thumbnail Image
    Publication
    Open Access
    Ion mobility spectrometry as an emerging tool for characterization of the volatile profile and identification of microbial growth in pomegranate juice
    (Elsevier, 2021-12-17) Castell Martínez, Ana; Arroyo Manzanares, Natalia; Hernández, Juan de Dios; Guillén, Isidro; Vizcaíno, Pascuali; López García, Ignacio Francisco; Hernández Córdoba, Manuel; Viñas López-Pelegrin, Pilar; Química Analítica
    Headspace - gas chromatography (HS-GC) coupled to ion mobility spectrometry (IMS) is proposed as an alternative to plate counting to detect and quantify the microbial contamination in pomegranate juice. Thus, contaminated samples by the yeast Saccharomyces cerevisiae were monitored during 6 non-consecutive days over two weeks using two types of preservatives (a sorbate/benzoate mixture and a natural preservative from vegetable extracts). IMS is an emerging technique with high potential for volatile organic compounds (VOCs) monitoring because its high sensitivity and separation power of ions. The fingerprint of the samples allowed to establish difference in the volatile composition of contaminated and non-contaminated samples. Ethyl acetate, ethyl butyrate and limonene were characterized obtaining limits of detection and quantification below 0.029 and 0.097 μg/g, respectively. Furthermore, chemometric models were performed to detect contaminated pomegranate juice and to assess the concentration of yeast, obtaining a validation success of 100 and 90.91%, respectively.