Spatially Offset Raman Spectroscopic (SORS) Analysis of Wine Alcoholic Fermentation: A Preliminary Study

Spatially offset Raman spectroscopy (SORS) is a non-invasive analytical technique that allows the analysis of samples through a container. This makes it an effective tool for studying food and beverage products, as it can measure the sample without being affected by the packaging or the container. In this study, a portable SORS equipment was used for the first time to analyse the alcoholic fermentation process of white wine. Different sample measurement arrangements were tested in order to determine the most effective method for monitoring the fermentation process and predicting key oenological parameters. The best results were obtained when the sample was directly measured through the glass container in which the fermentation was occurring. This allowed for the accurate monitoring of the process and the prediction of density and pH with a root mean square error of cross-validation (RMSECV) of 0.0029 g·L−1 and 0.04, respectively, and R2 values of 0.993 and 0.961 for density and pH, respectively. Additionally, the sources of variability depending on the measurement arrangements were studied using ANOVA-Simultaneous Component Analysis (ASCA)

Development of an integrated method of concentrationand immunodetection of bacteria

The microbial quality of water is a key aspect to avoid environmental and public health problems. The low pathogen concentration needed to produce a disease outbreak makes it essential to process large water volumes and use sensitive and specific methods such as immunoassays for its detection. In the present work, we describe the development of a device based on microfiltration membranes to integrate the concentration and the immunodetection of waterborne bacteria. A microfiltration membrane treatment protocol was designed to reduce the non-specific binding of antibodies, for which different blocking agents were tested. Thus, the proof of concept of the microbial detection system was also carried out using Escherichia coli as the bacterial pathogen model. E. coli suspensions were filtered through the membranes at 0.5 mL s−1, and the E. coli concentration measurements were made by absorbance, at 620 nm, of the resultant product of the enzymatic reaction among the horseradish peroxidase (HRP) bonded to the antibody, and the substrate 3,3′,5,5′-tetramethylbenzidine (TMB). The results showed that the homemade concentration system together with the developed membrane treatment protocol is able to detect E. coli cells with a limit of detection (LoD) of about 100 CFU in 100 mL.The authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (BACSYS pro- ject CTQ2014-54553-C3-1-R). N.U. and O.C. acknowledge funding from the People Programme (Marie Curie Actions) of the 7th Framework Programme of the E uropean Union (FP7/2007-2013), TECNIO-spring program from the Agency for Business Competitiveness of the Government of Catalonia (ACCIÓ). J.J.E. ac- knowledges financial support from the Catalan Industrial Doctorate pro- gram and Waterologies. S.L. and N.P. acknowledge financial support from Gas Natural Fenosa.Peer reviewe

A New Index to Detect Process Deviations Using IR Spectroscopy and Chemometrics Process Tools

Process analytical technologies (PATs) have transformed the beverage production management by providing real-time monitoring and control of critical process parameters through non-destructive measurements, such as those obtained with infrared (IR) spectroscopy and enabling process readjustment if necessary. New requirements in the analysis of beverages call for new methods, so in this article, we propose a method based on the construction of multivariate statistical process control (MSPC) charts from a new dissimilarity index (the evolving window dissimilarity index, EWDI) to monitor fermentation processes. The EWDI was applied to monitor wine alcoholic fermentation, the biochemical transformation of sugars into ethanol. Small-scale fermentations were carried out and analyzed using a portable mid-infrared spectrometer. In some of them, process deviations due to nitrogen deficiency or temperature changes were intentionally promoted to evaluate the performance of the EWDI. The MSPC charts build by using the fermentations carried out under normal operating conditions allowed identifying deviations of the fermentation in its early stages. Furthermore, the shape of the EWDI curve over time provides insights about the specific type of deviation occurring. These results show the potential of this new approach to improve the monitoring and control of key process stages in biochemical processes in the food industry, which allows maximizing quality and minimizing losses

Electrochromogenic Detection of Live Bacteria Using Soluble and Insoluble Prussian Blue

Microbial detection is crucial for the control and prevention of infectious diseases, being one of the leading causes of mortality worldwide. Among the techniques developed for bacterial detection, those based on metabolic indicators are progressively gaining interest due to their simplicity, adaptability, and, most importantly, their capacity to differentiate between live and dead bacteria. Prussian blue (PB) may act as a metabolic indicator, being reduced by bacterial metabolism, producing a visible color change from blue to colorless. This molecule can be present in two main forms, namely, the soluble and the insoluble, having different properties and structures. In the current work, the bacterial-sensing capacity of soluble and insoluble PB will be tested and compared both in suspensions as PB-NPs and after deposition on transparent indium tin oxide-poly(ethylene terephthalate) (ITO-PET) electrodes. In the presence of live bacteria, PB-NPs are metabolized and completely reduced to the Prussian white state in less than 10 h for soluble and insoluble forms. However, when electrodeposited on ITO-PET substrates, less than 1 h of incubation with bacteria is required for both forms, although the soluble one presents faster metabolic reduction kinetics. This study paves the way to the use of Prussian blue as a metabolic indicator for the early detection of bacterial infection in fields like microbial diagnostics, surface sterilization, food and beverage contamination, and environmental pollution, among others

Rapid detection of legionella pneumophila in drinking water, based on filter immunoassay and chronoamperometric measurement

Legionella is a pathogenic bacterium, ubiquitous in freshwater environments and able to colonise man-made water systems from which it can be transmitted to humans during outbreaks. The prevention of such outbreaks requires a fast, low cost, automated and often portable detection system. In this work, we present a combination of sample concentration, immunoassay detection, and measurement by chronoamperometry. A nitrocellulose microfiltration membrane is used as support for both the water sample concentration and the Legionella immunodetection. The horseradish peroxidase enzymatic label of the antibodies permits using the redox substrate 3,3′,5,5′-Tetramethylbenzidine to generate current changes proportional to the bacterial concentration present in drinking water. Carbon screen-printed electrodes are employed in the chronoamperometric measurements. Our system reduces the detection time: from the 10 days required by the conventional culture-based methods, to 2–3 h, which could be crucial to avoid outbreaks. Additionally, the system shows a linear response (R2 value of 0.99), being able to detect a range of Legionella concentrations between 101 and 104 cfu·mL−1 with a detection limit (LoD) of 4 cfu·mL−1.The authors acknowledge financial support from the Spanish Ministry of Science, Innovation and University [BACSYS projects CTQ2014-54553-C3-1-R and C3-2R] and [RTI2018-101974-B-C22]. J.J.E. acknowledges financial support from the Catalan Industrial Doctorate program [2017-DI-051] and Waterologies S.L.Peer reviewe

Rapid detection of Legionella pneumophila in drinking water, based on filter immunoassay and chronoamperometric measurement

Legionella is a pathogenic bacterium, ubiquitous in freshwater environments and able to colonise man-made water systems from which it can be transmitted to humans during outbreaks. The prevention of such outbreaks requires a fast, low cost, automated and often portable detection system. In this work, we present a combination of sample concentration, immunoassay detection, and measurement by chronoamperometry. A nitrocellulose microfiltration membrane is used as support for both the water sample concentration and the Legionella immunodetection. The horseradish peroxidase enzymatic label of the antibodies permits using the redox substrate 3,3',5,5'-Tetramethylbenzidine to generate current changes proportional to the bacterial concentration present in drinking water. Carbon screen-printed electrodes are employed in the chronoamperometric measurements. Our system reduces the detection time: from the 10 days required by the conventional culture-based methods, to 2-3 h, which could be crucial to avoid outbreaks. Additionally, the system shows a linear response (R2 value of 0.99), being able to detect a range of Legionella concentrations between 101 and 104 cfu·mL−1 with a detection limit (LoD) of 4 cfu·mL−