Impedance microbiology: quantification of bacterial content in milk by means of capacitance growth curves

Felice, C.J.; Madrid, Rossana E.; Olivera, J.M.; Rotger, V I; Valentinuzzi, Max E.

doi:10.1016/s0167-7012(98)00098-0

Cited by 118 publications

(74 citation statements)

References 17 publications

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“…These may include lactic 25 acid, acetic acid, carbon dioxide, ammonia, bicarbonate and urea, 26 the presence of which provokes a change in the ionic composition 27 of the growth media [2]. Thus, these changes can be measured and 28 related to bacterial concentration for determination of microbial 29 growth [3]. Since bacterial metabolism may significantly alter 30 electrical conductivity of the growth media, impedance technique 31 can be successfully applied for estimation of microbial biomass [4], 32 detection of microbial metabolism, as well as for determination of 33 the physiological state of bacteria growth [5][6][7].…”

Section: Q2mentioning

confidence: 99%

Fast determination of viable bacterial cells in milk samples using impedimetric sensor and a novel calibration method

Uría

Moral‐Vico

Abramova

et al. 2016

Electrochimica Acta

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A B S T R A C TAs a first stage toward the development of an impedimetric biosensor to quantify viable bacterial cells, this work defines the relationships between microbial growth and impedance changes associated with acidification of the culture medium. Escherichia coli bacterium was used as a model of a common pathogenic bacterium found in a foodstuff. Impedance was measured at a fix frequency of 10 kHz using interdigitated microelectrodes. Impedance changes were found to depend on the number of microorganisms in a sample. However, as the kinetics greatly depends on the bacterial concentration, it was not possible to obtain a single calibration curve in a wide concentration range at a fixed incubation time. To resolve this, a novel calibration method was proposed by measuring the sensor response at 270 and 390 min of incubation and taking a mean value. Obtained calibration plots were used to determine E. coli in a spiked milk samples. Performed experiments demonstrated the capacity of the method to detect E.coli concentrations in a range between 10 2 and 10 6 cfu mL À1 in milk in only 6 hours with 5-12% error margin.

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Section: Q2mentioning

confidence: 99%

Fast determination of viable bacterial cells in milk samples using impedimetric sensor and a novel calibration method

Uría

Moral‐Vico

Abramova

et al. 2016

Electrochimica Acta

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“…Impedance measurement, defined as the resistance to flow of an alternating current through a conducting material, can be used to monitor the growth of LAB [10] and to determine the shelf life and bacteriological quality of raw materials of different food products [6,15,29,30,32].…”

Section: Introductionmentioning

confidence: 99%

Influence of pH and temperature on the growth of Enterococcus faecium and Enterococcus faecalis

Morandi

Brasca

Alfieri

et al. 2005

Lait

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-A total of 70 enterococcal strains isolated from traditional Italian raw milk cheeses were identified by API 20 Strep and Biolog GP. All the identifications were confirmed by species-specific PCR. Four species of genus Enterococcus were found: E. faecalis, E. faecium, E. durans and E. hirae. E. faecalis and E. faecium were the dominant enterococcal species isolated in artisanal cheeses. According to the most representative species and the origin of isolation, 21 strains (11 E. faecalis and 10 E. faecium) were selected for the conductimetric analysis. The influence of pH (5.0; 5.5; 6.0 and 6.5) and temperature (25 °C and 37 °C) on the metabolism and the development of enterococci was evaluated by determination of Generation Time (GT), Detection Time (DT) and the maximum conductance value (∆µS) of the curve during a period of 48 hours. Conductance trials showed that both species were able to adapt to adverse cultural conditions (low values of pH and temperature) during cheese-making and ripening. E. faecalis appeared to be less sensitive on the whole. In the worst conditions (pH 5.0, 25 °C), after an adaptation phase (about 10 h), these microorganisms showed GT values almost double those at 37 °C. The same behavior can occur in cheese, where enterococci can reach numbers of up to 10 5 -10 8 cfu·g -1 during ripening. This could explain the fact that enterococci (in particular, E. faecalis and E. faecium) represent the typical and important microflora in raw milk cheese. E. faecalis / E. faecium / conductimetric analysis / pH / temperature / growthRésumé -Influence du pH et de la température sur la croissance d'Enterococcus faecalis et Enterococcus faecium. Un total de 70 souches d'entérocoques, isolées de certains fromages italiens traditionnels, a été identifié à l'aide des galeries API 20 Strep et Biolog GP. Toutes les identifications ont été confirmées par PCR espèce-spécifique. Quatre espèces de ce genre ont été isolées : E. faecalis, E. faecium, E. durans et E. hirae. E. faecalis et E. faecium étaient les espèces dominantes isolées des fromages artisanaux. Un total de 21 souches (11 E. faecalis et 10 E. faecium) a été sélec-tionné pour les analyses de conductimétrie selon les espèces les plus représentées et selon l'origine de l'isolement. L'influence du pH (5,0 ; 5,5 ; 6,0 et 6,5) et de la température (25 °C et 37 °C) sur le métabolisme et sur le développement des entérocoques a été évaluée par détermination du temps de génération (GT), du temps de détection (DT) et de la valeur conductimétrique maximale (∆µS) de la courbe au cours d'une période de 48 h. Les mesures de conductance ont démontré que les deux espèces ont la capacité de s'adapter aux conditions de culture défavorables (valeurs faibles du pH et de la température) aussi bien pendant la fabrication du fromage que l'affinage. Les deux espèces ont un comportement différent : E. faecalis s'est avéré être moins sensible. Dans les plus mauvaises conditions (pH 5,0-25 °C), après la phase d'adaptation (environ 10 h), ces micro-organismes montrent...

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“…One of the major applications of microbiological impedance devices is to determine the initial bacteria count in a food medium through a technique called Impedance Detection Time (IDT) [12][13][14][15][16]. The initial bacteria count obtained from IDT is then used to estimate the useful shelf life of a food product.…”

Section: Introductionmentioning

confidence: 99%

Remote Query Resonant-Circuit Sensors for Monitoring of Bacteria Growth: Application to Food Quality Control

Ong

Bitler

Grimes

et al. 2002

Sensors

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This paper presents a technique for in-situ remote query monitoring of bacteria growth utilizing a printed thin or thick-film sensor comprised of an inductor-capacitor (LC) resonant circuit. The sensor, which is placed within the biological medium of interest and remotely detected using a loop antenna, measures the complex permittivity of the medium. Since bacteria growth increases the complex permittivity of a biological medium the LC sensor can be used to determine bacteria concentration. This paper presents results on monitoring of three different bacteria strains, Bacillus subtilis, Escherichia coli JM109, and Pseudomonas putida, demonstrating application of the sensor for monitoring bacteria growth in milk, meat, and beer. Due to its low unit cost and remote query detection, the sensor is potentially useful for commercial scale monitoring of food quality.

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Impedance microbiology: quantification of bacterial content in milk by means of capacitance growth curves

Cited by 118 publications

References 17 publications

Fast determination of viable bacterial cells in milk samples using impedimetric sensor and a novel calibration method

Fast determination of viable bacterial cells in milk samples using impedimetric sensor and a novel calibration method

Influence of pH and temperature on the growth of Enterococcus faecium and Enterococcus faecalis

Remote Query Resonant-Circuit Sensors for Monitoring of Bacteria Growth: Application to Food Quality Control

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