Spectroscopic Differentiation and Quantification of Microorganisms in Apple Juice

Ways to reduce the labor intensiveness of applying the method of optical estimation of microbial cell concentration in suspension

The labor intensity (in hours) of the optical method of microbial cell counting in suspension compared to the method of microbial cell counting using a Goryaev chamber is evaluated. The relevance of assessing the production labor intensity of microbial cell counting methods in suspension is related to the need to use them in many studies. Often the commonly used methods are too labour-intensive, time-consuming, or require expensive equipment. A comparative experiment was carried out with our previously developed "Method for optical estimation of microbial cell concentration in suspension" (Priority certificate No. 2016141859 dated 25.10.2016) and the method of microbial cell counting using a Goryaev chamber. Production labor intensity of the measurements performed was calculated in hours according to the formula: Tp=Tt+Tob, where Tp is production labour input, Tt is technological labour input, Tob is maintenance labour input. Technological labour input of measurements with use of Goryaev's chamber made up 32,18 ± 0,95, whereas with optical method - 1,03±0,06 (reliability of differences at p<0,01) at amount of measurements n = 100. Labour input of service at optical method 0,24 ± 0,03, at application of method with use of Goryaev chamber 0,15±0,01 hours. Labour input of measurements of concentration of microbial cells in suspension at application of method of measurement with Goryaev chamber remains (p<0,01) higher than at an optical method of estimation, 32,33±0,96 and 1,27±0,05 hours accordingly. When using the optical method of concentration estimation in the suspension it is necessary to carry out not a small amount of necessary mathematical calculations, which in the future, probably, corrected by creating a special program for a personal computer. The labour input of results obtained by measuring by optical evaluation of the concentration of microbial cells in suspension is lower than that obtained by using a measurement method using a Goryaev chamber. Taking into consideration that its implementation does not require purchase of special equipment as in turbidimetry, its cost-effectiveness compared to existing ones is obvious.

Overview of Monitoring Techniques for Evaluating Water Quality at Potable Reuse Treatment Facilities

Needless to say, the safety of treated water for potable reuse must be definitively ensured. Numerous methods are available for assessing water quality; it's important to understand their challenges and limitations.

An investigation of inactivation mechanisms of Bacillus amyloliquefaciens spores in non-thermal plasma of ambient air

BACKGROUND

To utilize the potential of non-thermal plasma technologies for food safety control and sanitation, the inactivation mechanisms of Bacillus amyloliquefaciens spores by non-thermal plasma of ambient air (NTP-AA) were investigated using scanning electron microscopy, atomic force microscopy, attenuated total reflectance Fourier transform infrared spectroscopy with chemometric analysis and proton nuclear magnetic resonance spectroscopy, aiming to probe both the morphological and biochemical changes occurring in spores during the kinetic inactivation process.

RESULTS

Kinetic analysis indicates that there is no intrinsic D-value (i.e. time required to inactivate 90% of the spores) in spore inactivation by NTP-AA because we observed non-linear (biphasic) inactivation kinetics and, in addition, the inactivation rate depended on the initial spore concentration and how the spores were exposed to the reactive species in the NTP-AA. The presence of suitable amount of water in the NTP-AA field accelerates spore inactivation.

CONCLUSION

Progressive erosion of spore surface by NTP-AA with ensuing or concomitant biochemical damage, which includes the alteration of structural proteins, internal lipids and the loss of dipicolinic acid content from the spore core, represent the main mechanisms of inactivation, and there is evidence that reactive NTP-AA species could penetrate the cortex and reach the core of spores to cause damage. © 2018 Society of Chemical Industry.

Space-variant video compression and processing in digital holographic microscopy sensor networks with application to potable water monitoring

Water-related diseases affect societies in all parts of the world. Online sensors are considered a solution to the problems associated with laboratory testing in potable water. One of the most active research areas of such online sensors has been within optics. Digital holographic microscopy (DHM) has the potential to rival state-of-the-art techniques such as advanced turbidity measurement. However, its use as an online sensor is limited by the large data requirements typical for digital holographic video. In this paper, we provide a solution that permits DHM to be applied to a whole class of online remote sensor networks, of which potable water analysis is one example. The designed sensors incorporate a novel space-variant quantization algorithm to preprocess each frame of a video sequence before transmission over a network. The system satisfies the generally accepted requirements of an online system: automated, near real-time, and operating in a real environment. To verify the effectiveness of the design, we implemented and evaluated it in an active potable water facility.

Fourier Transform Near-Infrared Spectroscopy and Chemometrics To Predict Zygosacchromyces rouxii in Apple and Kiwi Fruit Juices

This study investigated the capability of near-infrared spectroscopy (NIRS) to predict the concentration of Zygosaccharomyces rouxii in apple and kiwi fruit juices. The yeast was inoculated in fresh kiwi fruit juice ( n = 68), reconstituted kiwi juice ( n = 85), and reconstituted apple juice ( n = 64), followed by NIR spectra collection and plate counting. A principal component analysis indicated direct orthogonal signal correction preprocessing was suitable to separate spectral samples. Parameter optimization algorithms increased the performance of support vector machine regression models developed in a single variety juice system and a multiple variety juice system. Single variety juice models achieved accurate prediction of Z. rouxii concentrations, with the limit of quantification at 3 to 15 CFU/mL ( R² = 0.997 to 0.999), and the method was also feasible for Hanseniaspora uvarum and Candida tropicalis. The best multiple variety juice model obtained had a limit of quantification of 237 CFU/mL ( R² = 0.961) for Z. rouxii. A Bland-Altman analysis indicated good agreement between the support vector machine regression model and the plate counting method. It suggests that NIRS can be a high-throughput method for prediction of Z. rouxii counts in kiwi fruit and apple juices.

Multifunctional bacterial imaging and therapy systems

Advanced antibacterial materials are classified and introduced, and their applications in multimodal imaging and therapy are reviewed.

Detection of poultry meat specific bacteria using FTIR spectroscopy and chemometrics

FTIR spectra of poultry meat specific bacteria viz. Salmonella enteritidis, Pseudomonas ludensis, Listeria monocytogenes and Escherichia coli were collected and investigated for identification of spectral windows capable of bacterial classification and quantification. Two separate datasets obtained at different times were used in the study to check reproducibility of results. Multivariate data analysis techniques viz. principal component analysis (PCA), partial least-squares discriminant analysis (PLSDA) and soft independent modelling of class analogy (SIMCA) were used in the analysis. Using full cross-validation and separate calibration and prediction datasets, the highest correct classification results for SIMCA and PLSDA were achieved in spectral window (1800-1200 cm-1) for both datasets. The window was also tested then for quantification of different bacteria and it had been observed that PLS models had better R values for classification (R = 0.984) than predicting various concentration levels (R = 0.939) of all four poultry specific bacteria inoculated in distilled water. The identified spectral window 1800-1200 cm-1 also demonstrated potential for 100% correct classification of chicken salami samples contaminated with S. enteritidis and P. ludensis from control using SIMCA. However, this wavenumber range yielded few misclassifications using PLS-DA approach. Thus FTIR spectroscopy in combination with chemometrics is a powerful technique that can be developed further to differentiate bacteria directly on poultry meat surface.

Nano/micro and spectroscopic approaches to food pathogen detection

Despite continuing research efforts, timely and simple pathogen detection with a high degree of sensitivity and specificity remains an elusive goal. Given the recent explosion of sensor technologies, significant strides have been made in addressing the various nuances of this important global challenge that affects not only the food industry but also human health. In this review, we provide a summary of the various ongoing efforts in pathogen detection and sample preparation in areas related to Fourier transform infrared and Raman spectroscopy, light scattering, phage display, micro/nanodevices, and nanoparticle biosensors. We also discuss the advantages and potential limitations of the detection methods and suggest next steps for further consideration.

Detection of Escherichia coli O157:H7 and Salmonella typhimurium using filtration followed by Fourier-transform infrared spectroscopy

Fourier-transform infrared spectroscopy has been successfully used as a nondestructive method for identifying, distinguishing, and classifying pathogens. In this study, a less time-consuming Fourier-transform infrared procedure was developed to identify Escherichia coli O157:H7 and Salmonella Typhimurium. Samples containing 10(9) CFU/ml were prepared in tryptic soy broth and then serially diluted (up to eight times) to obtain bacterial solutions of 10(9) to 10 CFU/ml. These dilutions were incubated at 37 degrees C for 6 h, samples were filtered through a Metricel filter hourly (for 0 to 6 h), and spectra were obtained using a ZnSe contact attenuated total reflectance accessory on a Continu mum infrared microscope. Midinfrared spectra (4,000 to 700 cm(-1)) of Salmonella Typhimurium and E. coli O157:H7 were generated, and peak areas in the region of 1,589 to 1,493 cm(-1) were used to detect the pathogens. Initially, detection limits were between 10(6) and 10(7) CFU/ml without preenrichment, and samples starting with 500 CFU/ml were detectable following incubation for 6 h, when counts reached at least 10(6) CFU/ ml. Compared with results of previously published studies in which Fourier-transform infrared spectroscopy was used to identify select pathogens, this method is more rapid and less expensive for practical large-scale sample analysis.