Feasibility of Lactobacilli Concentration Detection in Beer by Automated Impedance Technique

Riccò

2017

J. Sens. Sens. Syst.

311

160

Abstract. Electrical impedance spectroscopy (EIS), in which a sinusoidal test voltage or current is applied to the sample under test to measure its impedance over a suitable frequency range, is a powerful technique to investigate the electrical properties of a large variety of materials. In practice, the measured impedance spectra, usually fitted with an equivalent electrical model, represent an electrical fingerprint of the sample providing an insight into its properties and behavior. EIS is used in a broad range of applications as a quick and easily automated technique to characterize solid, liquid, semiliquid, organic as well as inorganic materials. This paper presents an updated review of EIS main implementations and applications.

Section: Impedance Microbiologymentioning

confidence: 92%

Electrical impedance spectroscopy (EIS) for biological analysis and food characterization: a review

Riccò

2017

J. Sens. Sens. Syst.

311

160

“…These techniques are competitive with the reference methods in terms of measurement speed, but require expensive instrumentation and/or are characterized by low accuracy. In this context, Electrochemical Impedance Spectroscopy (EIS) is a very promising technique that, in recent years, has been used for the characterization of different food products such as: apple bruise detection [15]; control of persimmons" ripening stage [16]; automatic classification [17] and control of the freezing process of ice-cream mixes [18]; detection of bacterial concentration in ice-cream [19,20], raw milk [21], beer [22] and water [23]. The method consists in the application of a sinusoidal test voltage in a broad range of frequencies to the sample under test (SUT) and in the measurements of its electrical behavior, i.e.…”

mentioning

confidence: 99%

Fast and Accurate Determination of Olive Oil Acidity by Electrochemical Impedance Spectroscopy

Lecce²,

Toschi

et al. 2014

IEEE Sensors J.

Virgin olive oil is an important ingredient of the Mediterranean diet highly appreciated for its beneficial health effects due to the presence of mono-unsaturated fatty acids and antioxidant properties. The olive oil quality is defined by many parameters, among which acidity and peroxide index and according to international regulations, these two determinations are carried out in laboratory environment, by means of manual titration. This kind of method, however, cannot be used on oil production sites, where, instead, it would be desirable to know the main characteristics of the oil for proper product classification.In this paper a new technique to measure olive oil acidity by electrical conductance is presented that allows for fast, costeffective and on-site measurements. Such a technique has been validated with a set of 55 olive oil samples. Two different oil emulsions have been used and compared for the measurements: based on a hydro-alcoholic solution (60% ethanol 40% distilled water) and distilled water, respectively. The data show that the electrical conductance of the emulsion with hydro-alcoholic solution is a strong function of the olive oil acidity, that can be estimated with good accuracy (R 2 = 0.9308). The experiments with distilled water, instead, exhibit no significant correlation between oil acidity and emulsion conductance that, however, is found to provide information about peroxide index, polyphenols content and filtration technique.Furthermore, using both types of emulsions to compensate for conductance variations other than free fatty acids the accuracy in acidity determination can be improved reaching R 2 = 0.9786.

“…IM can be easily implemented in automatic form and provides results in a shorter time compared to the PCT. IM has been successfully tested for bacterial concentration measurements in various types of samples, such as ice cream (Grossi et al, 2008(Grossi et al, , 2010, meat (Firstenberg-Eden, 1983), vegetables (Hardy et al, 1977), raw milk (Grossi et al, 2011a), fresh water (Grossi et al, 2013), beer (Pompei et al, 2012), and human urine samples (Settu et al, 2015), and to test the efficiency of various antibiotics and chemical preservatives (Zhou and King, 1995).…”

Section: Introductionmentioning

confidence: 99%

A portable sensor system for bacterial concentration monitoring in metalworking fluids

Parolin

Vitali

et al. 2018

J. Sens. Sens. Syst.

Abstract. The detection of bacterial concentrations in metalworking fluids (MWFs), oil-in-water emulsions used in the cutting industries for cooling and lubrication, is important in order to extend the product life-cycle and plan its disposal according to regulations and legislations. The standard method of measuring culturable bacterial concentration is the plate count technique (PCT) that, however, has long response times and is not suitable for automatic implementation outside a laboratory. In this paper a portable sensor system that measures the bacterial concentration in liquid and semi-liquid media exploiting impedance microbiology is presented and tested for the application of MWF microbial monitoring. A set of MWF samples, taken from metalworking plants, have been tested and good agreement has been found between the system response and that of the PCT. The proposed system allows automated bacterial concentration measurements with shorter response times than the PCT (4 to 24 h vs. 24 to 72 h) and is suitable for in-the-field MWF monitoring.