Intrinsic Fluorescence Markers for Food Characteristics, Shelf Life, and Safety Estimation: Advanced Analytical Approach

Spectrophotofluorometric assay of Sulfaguanidine in Milk whey

The methylene blue fluorescence quenching and bromocresol purple spectrophotometric methods were applied to achieve the detection of sulfaguanidine in whey. The quenching of the fluorescence marker by sulfaguanidine in whey was used to elucidate the effect of the quencher on the Stern-Volmer quenching constant (KSV) values. The interaction of methylene blue with sulfaguanidine increases in whey by 3 times compared to water (KSV = 3 × 103 M-1 and KSV = 1 × 103 M-1, respectively). The value of the Stern-Volmer quenching constant KSV = 4 × 104 M-1 is the highest for quenching of whey fluorescence by bromocresol purple. The obtained results were applied as a spectral method for determining the concentration of sulfaguanidine in whey. Analytic emission (348, 430 and 700 nm) and absorption (259, 435 and 590 nm) wavelengths were used. The concentration for detecting sulfaguanidine in whey was 5 × 10-7 M (0.01 mg/mL) which is an order of magnitude lower the limit of spectrophotometric method.

What Can Fluorescence Tell Us About Wine?

Rapid and cost-effective measurements of the autofluorescence of wine can provide valuable information on the brand, origin, age, and composition of wine and may be helpful for the authentication of wine and detection of forgery. The list of fluorescent components of wines includes flavonoids, phenolic acids, stilbenes, some vitamins, aromatic amino acids, NADH, and Maillard reaction products. Distinguishing between various fluorophores is not simple, and chemometrics are usually employed to analyze the fluorescence spectra of wines. Front-face fluorescence is especially useful in the analysis of wine, obviating the need for sample dilution. Front-face measurements are possible using most plate readers, so they are commonly available. Additionally, the use of fluorescent probes allows for the detection and quantification of specific wine components, such as resveratrol, oxygen, total iron, copper, hydrogen sulfite, and haze-forming proteins. Fluorescence measurements can thus be useful for at least a preliminary rapid evaluation of wine properties.

The development and application of SERS-based lateral flow immunochromatography in the field of food safety

Surface-Enhanced Raman Scattering-Lateral Flow Immunoassay (SERS-LFIA) inherits the advantages of simplicity, rapidness, and stability from Lateral Flow Immunoassay (LFIA), while integrating the sensitivity and accuracy of SERS, thereby attracting extensive attention in the field of food safety monitoring. This paper delves into the design strategies and principles underlying SERS-LFIA, introducing the detection formats based on SERS and contrasting the differences between traditional Raman molecules and those located in the Raman-silent region. It analyzes two immunoassay methods, namely sandwich and competitive, along with their respective applications. Importantly, by reviewing the applications of SERS-LFIA in food safety monitoring over the past 5 years, this paper summarizes the challenges faced by SERS-LFIA technology in practical applications and development. Furthermore, it provides a forward-looking perspective on the future development of SERS-LFIA. As a pivotal analytical method in the field of food safety monitoring, SERS-LFIA is demonstrating immense potential. It is hoped that this paper will offer valuable insights for the future development and application of SERS-LFIA.

Phage-derived proteins: Advancing food safety through biocontrol and detection of foodborne pathogens

The emergence of antimicrobial-resistant foodborne pathogens poses a continuous health risk and economic burden as they can easily spread through contaminated food. Therefore, the demand for new antimicrobial agents to address this problem is steadily increasing. Similarly, the development of rapid, sensitive, and accurate pathogen detection tools is a prerequisite for ensuring food safety. Phage-derived proteins have become innovative tools for combating these pathogens because of their potent antimicrobial activity and host specificity. Phage proteins are relatively free from regulation compared to phages per se, and there are no concerns about the transduction of harmful genes. With recent progress in next-generation sequencing technology, the analysis of phage genomes has become more accessible, and numerous phage proteins with potential for biocontrol and detection have been identified. This review provides a comprehensive overview of phage protein research on food safety from 2006 to the present, a pivotal period marked by the certification of phages as Generally Recognized As Safe (GRAS). Emphasizing recent advancements, we investigated the diverse applications of various phage proteins for biocontrol and detection purposes. While highlighting the successful implementation of these proteins, we also address the current bottlenecks and propose strategies to overcome these challenges. By summarizing the current state of research on phage-derived proteins, this review contributes to a deeper understanding of their potential as effective antimicrobial agents and tools for detecting foodborne pathogens.

Application of Spectrofluorimetry to Evaluate Quality Changes in Stored Blue Honeysuckle Berry (Lonicera kamtschatica) Preserves

The aim of this study was to use a rapid and non-invasive spectrofluorimetric method to evaluate the qualitative changes occurring in stored Kamchatka berry preserves. Honeysuckle berries were preserved by freezing (-24 °C) and pasteurisation with and without sugar addition. Pasteurised samples were stored at 6 ± 1 °C and 22 ± 1 °C for 9 months. During storage, spectrofluorimetric spectra in the bioactive compounds' fluorescence range were registered. The obtained synchronous spectra were used in a statistical analysis involving principal component analysis (PCA) and linear discriminant analysis (LDA). The analysis of both types of registered spectra indicated that sugar addition could stabilise some phenolic compounds, like gallic acid, p-coumaric acid, and phloridzin. Moreover, some differences in the degradation rate of each analysed compound were observed depending on the preservation method used. Besides the phenolic compounds, other fluorescent compounds like B-vitamins and chlorophyll forms were also observed. Pasteurisation caused the distinct degradation of protochlorophyll forms, whereas practically no changes in the amounts of vitamins B3 and B9 were observed. Based on the results of statistical analyses of PCA and LDA, the effect on the products' composition was moderate for the storage time and relatively low in the case of the storage temperature. The obtained results indicated that spectrofluorimetry would be a useful method for the detailed characterisation of fruit products.

Effects of mining activities and municipal wastewaters on element accumulation and integrated biomarker responses of the European chub (Squalius cephalus)

This study aimed to determine concentrations of 29 elements in the gills and liver as well as biomarker response in gills, liver, and blood of European chub from Pek River (exposed to long-term mining activities), and to compare these findings with individuals from Ibar River (influenced by emission of treated municipal wastewater) and Kruščica reservoir (source of drinking water) using inductively-coupled plasma optical emission spectrometry (ICP-OES). The metal pollution index (MPI) was also calculated. Supporting analyses for the detection of the municipal wastewater presence at investigated localities included analyses of microbiological indicators (total coliforms and Escherichia coli) of faecal pollution. We have assessed biomarker responses from molecular to organism level using the condition index, comet assay, micronucleus test, oxidative stress parameters, histopathological alterations, and fluorescence spectroscopy parameters. Multibiomarker analysis was summarized by Integrated Biomarker Response v2 (IBRv2). Among these locations, Kruščica exhibited the lowest, whereas the Pek River displayed the highest values for both categories of indicator bacteria. Due to the porphyry copper ores mining, individuals from Pek River had several times higher Cu concentrations in both gills and liver compared to the other localities which was confirmed by biomarker responses and IBRv2 value. On the contrary, fish from Kruščica reservoir were the least affected by elemental pollution which is also confirmed by low MPI and IBRv2 values. Responses of biomarkers correspond to the elemental accumulation in the liver and gills of the Ibar River are positioned between the Pek River and Kruščica reservoir. Of all the biomarkers analyzed in this study, the condition index was the least sensitive. The results of this study showed that fluorescence spectroscopy may be a method for fast screening of structural changes in gills caused by the pollution burden.

Unveiling angular sweep total fluorescence Spectroscopy:A novel multidimensional technique for analysis of complex multi-fluorophoric systems

Analyzing multi-fluorophoric real systems without pre-processing is challenging, often addressed with unconventional fluorescence techniques and chemometrics. In this context, we introduce a novel addition - 'Angular Sweep Total Fluorescence Spectroscopy (ASTFS),' to the arsenal of multidimensional steady-state fluorescence spectroscopic techniques. ASTFS utilizes a series of variable angle synchronous fluorescence spectra, strategically covering the fluorescence region between the first and second-order Rayleigh scattering ridges. The plot features a minimal data matrix size, avoids Rayleigh scattering signals, and incurs no blind regions. The study delves into the instrumental configurations for spectral acquisition, highlights the enhanced spectral resolution due to the band-narrowing effect, and discusses other notable features of the ASTFS plot. Further, this technique is reported to be effective in analyzing analytes in complex systems with strong background fluorescence, such as milk. The antibiotic- Norfloxacin is quantified via minimal pre-processing in milk samples and yields excellent analytical figures of merit.

Light-Emitting-Diode-Induced Fluorescence from Organic Dyes for Application in Excitation-Emission Fluorescence Spectroscopy for Food System Analysis

An experimental study is presented on the possibility of using the fluorescence from organic dyes as a broadband light source together with a monochromator for applications in excitation-emission matrix (EEM) fluorescence spectroscopy. A high-power single-chip light-emitting diode (LED) was chosen as an excitation source with a central output wavelength at 365 nm to excite a fluorescent solution of Coumarin 1 dye dissolved in ethanol. Two excitation configurations were investigated: direct excitation from the LED and excitation through an optical-fiber-coupled LED. A Czerny-Turner monochromator with a diffraction grating was used for the spectral tuning of the fluorescence. A simple method was investigated for increasing the efficiency of the excitation as well as the fluorescence signal collection by using a diffuse reflector composed of barium sulfate (BaSO4) and polyvinyl alcohol (PVA). As research objects, extra-virgin olive oil (EVOO), Coumarin 6 dye, and Perylene, a polycyclic aromatic hydrocarbon (PAH), were used. The results showed that the light-emitting-diode-induced fluorescence was sufficient to cover the losses on the optical path to the monochromator output, where a detectable signal could be obtained. The obtained results reveal the practical possibility of applying the fluorescence from dyes as a light source for food system analysis by EEM fluorescence spectroscopy.

Synchronous Front-Face Fluorescence Spectra: A Review of Milk Fluorophores

Milk is subjected to different industrial processes, provoking significant physicochemical modifications that impact milk's functional properties. As a rapid and in-line method, front-face fluorescence can be used to characterize milk instead of conventional analytical tests. However, when applying fluorescence spectroscopy for any application, it is not always necessary to determine which compound is responsible for each fluorescent response. In complex matrixes such as milk where several variables are interdependent, the unique identification of compounds can be challenging. Thus, few efforts have been made on the chemical characterization of milk' fluorescent spectrum and the current information is dispersed. This review aims to organize research findings by dividing the milk spectra into areas and concatenating each area with at least one fluorophore. Designations are discussed by providing specific information on the fluorescent properties of each compound. In addition, a summary table of all fluorophores and references cited in this work by area is provided. This review provides a solid foundation for further research and could serve as a central reference.