Potential application of electronic nose technology in brewery

Recent Progress in Electronic Noses for Fermented Foods and Beverages Applications

Fermented foods and beverages have become a part of daily diets in several societies around the world. Emitted volatile organic compounds play an important role in the determination of the chemical composition and other information of fermented foods and beverages. Electronic nose (E-nose) technologies enable non-destructive measurement and fast analysis, have low operating costs and simplicity, and have been employed for this purpose over the past decades. In this work, a comprehensive review of the recent progress in E-noses is presented according to the end products of the main fermentation types, including alcohol fermentation, lactic acid fermentation, acetic acid fermentation and alkaline fermentation. The benefits, research directions, limitations and challenges of current E-nose systems are investigated and highlighted for fermented foods and beverage applications.

A ratiometric fluorescence sensor for 5-hydroxymethylfurfural detection based on strand displacement reaction

Since 5-hydroxymethylfurfural (HMF) becomes a neo-forming contaminant with latent harm to human health, development of new method for highly sensitive detection of HMF is extremely desirable. Herein, a novel ratiometric fluorescence sensor based on strand displacement reaction and magnetic separation was designed for sensitive and selective detection of HMF with the help of MnO₂ nanosheets. The aldehyde-functionalized DNA (S0-CHO) and HMF competed for binding to amino-functionalized magnetic beads (NH₂-MBs). Then, S0-CHO was collected from supernatant by magnetic separation. In the presence of HMF, the obtained S0-CHO induced the formation of T-shaped DNA by strand displacement reaction (SDR), lighting the fluorescence of FAM. In the absence of HMF, no S0-CHO was present to ignite T-shaped DNA. In this situation, fluorescence of Cy5 was turned on. Thus, a ratiometric fluorescence sensor for high-sensitive detection of HMF was developed. The sensor has a wide linear range from 5 nM to 5 μM. It also exhibited high selectivity against other potential interfering substances. It has been successfully applied to analyze HMF in food samples. The method has potential to be expanded to detect other molecules containing aldehyde groups and further be applied in food safety, environment and other fields.

Application of Neuromorphic Olfactory Approach for High-Accuracy Classification of Malts

Current developments in artificial olfactory systems, also known as electronic nose (e-nose) systems, have benefited from advanced machine learning techniques that have significantly improved the conditioning and processing of multivariate feature-rich sensor data. These advancements are complemented by the application of bioinspired algorithms and architectures based on findings from neurophysiological studies focusing on the biological olfactory pathway. The application of spiking neural networks (SNNs), and concepts from neuromorphic engineering in general, are one of the key factors that has led to the design and development of efficient bioinspired e-nose systems. However, only a limited number of studies have focused on deploying these models on a natively event-driven hardware platform that exploits the benefits of neuromorphic implementation, such as ultra-low-power consumption and real-time processing, for simplified integration in a portable e-nose system. In this paper, we extend our previously reported neuromorphic encoding and classification approach to a real-world dataset that consists of sensor responses from a commercial e-nose system when exposed to eight different types of malts. We show that the proposed SNN-based classifier was able to deliver 97% accurate classification results at a maximum latency of 0.4 ms per inference with a power consumption of less than 1 mW when deployed on neuromorphic hardware. One of the key advantages of the proposed neuromorphic architecture is that the entire functionality, including pre-processing, event encoding, and classification, can be mapped on the neuromorphic system-on-a-chip (NSoC) to develop power-efficient and highly-accurate real-time e-nose systems.

Synthesis and morphological studies of Tc-99m-labeled lupulone-conjugated Fe3O4@TiO2 nanocomposite, and in vitro cytotoxicity activity on prostate cancer cell lines

The purpose of this study was to develop a multifunctional theranostic probe for imaging (magnetic resonance imaging [MRI] and single-photon emission computed tomography [SPECT]) and therapy (photodynamic therapy). For this purpose, Tc-99m-labeled lupulone-conjugated Fe₃O₄@TiO₂ nanocomposites (^99mTc-DTPA-Fe₃O₄@TiO₂-HLP and ^99mTc-DTPA-Fe₃O₄@TiO₂-ALP nanocomposites) were synthesized. The average diameter of the nanocomposites was 171 ± 20 nm as seen on transmission electron microscopy images. Fe₃O₄@TiO₂ nanocomposites exhibited fluorescence spectra at an emission wavelength of 314 nm. Lupulone-conjugated Fe₃O₄@TiO₂ nanocomposites were spherical-shaped with a suitable dispersion and without visible aggregation, and their radiolabeling yields were over 85%. Healthy (RWPE-1 normal human prostate epithelial cell line) and cancer prostate cell lines (PC-3 human prostate cancer cell line) were used to determine the in vitro biological behavior of the nanocomposites. The PC-3 cells treated with lupulone-conjugated Fe₃O₄@TiO₂ nanocomposites showed a lower cell viability compared with RWPE-1 cells treated with lupulone-conjugated Fe₃O₄@TiO₂ nanocomposites. Lupulone-modified Fe₃O₄@TiO₂ nanocomposites may serve in the future as a multifunctional probe for positron emission tomography (PET)/MRI, photodynamic therapy, and hyperthermia therapy of cancer.

Smart Detection of Faults in Beers Using Near-Infrared Spectroscopy, a Low-Cost Electronic Nose and Artificial Intelligence

Early detection of beer faults is an important assessment in the brewing process to secure a high-quality product and consumer acceptability. This study proposed an integrated AI system for smart detection of beer faults based on the comparison of near-infrared spectroscopy (NIR) and a newly developed electronic nose (e-nose) using machine learning modelling. For these purposes, a commercial larger beer was used as a base prototype, which was spiked with 18 common beer faults plus the control aroma. The 19 aroma profiles were used as targets for classification ma-chine learning (ML) modelling. Six different ML models were developed; Model 1 (M1) and M2 were developed using the NIR absorbance values (100 inputs from 1596–2396 nm) and e-nose (nine sensor readings) as inputs, respectively, to classify the samples into control, low and high concentration of faults. Model 3 (M3) and M4 were based on NIR and M5 and M6 based on the e-nose readings as inputs with 19 aroma profiles as targets for all models. A customized code tested 17 artificial neural network (ANN) algorithms automatically testing performance and neu-ron trimming. Results showed that the Bayesian regularization algorithm was the most adequate for classification rendering precisions of M1 = 95.6%, M2 = 95.3%, M3 = 98.9%, M4 = 98.3%, M5 = 96.8%, and M6 = 96.2% without statistical signs of under- or overfitting. The proposed system can be added to robotic pourers and the brewing process at low cost, which can benefit craft and larger brewing companies.

Optimization of Classification Prediction Performances of an Instrumental Odour Monitoring System by Using Temperature Correction Approach

Odour emissions generated by industrial and environmental protection plants are often a cause of nuisances and consequent conflicts in exposed populations. Their control is a key action to avoid complaints. Among the odour measurement techniques, the sensory-instrumental method with the application of Instrumental Odour Monitoring Systems (IOMSs) currently represents an effective solution to allow a continuous classification and quantification of odours in real time, combining the advantages of conventional analytical and sensorial techniques. However, some aspects still need to be improved. The study presents and discusses the investigation and optimization of the operational phases of an advanced IOMS, applied for monitoring of environmental odours, with the aim of increasing their performances and reliability of the measures. Accuracy rates of over 98% were reached in terms of classification performances. The implementation of automatic correction systems for the resistance values of the measurement sensors, by considering the influence of the temperature, has been proven to be a solution to further improve the reliability of IOMS. The proposed approach was based on the application of corrective coefficients experimentally determined by analyzing the correlation between resistance values and operating conditions. The paper provides useful information for the implementation of real-time management activities by using a tailor-made software, able to increase and enlarge the IOMS fields of application.

Raspberry, Rape, Thyme, Sunflower and Mint Honeys Authentication Using Voltammetric Tongue

The aim of this study was to authenticate five types of Romanian honey (raspberry, rape, thyme, sunflower and mint) using a voltammetric tongue (VE tongue) technique. For the electronic tongue system, six electrodes (silver, gold, platinum, glass, zinc oxide and titanium dioxide) were used. The results of the melissopalynological analysis were supplemented by the data obtained with the electronic voltammetric tongue system. The results were interpreted by means of principal component analysis (PCA) and linear discriminant analysis (LDA). In this way, the usefulness of the working electrodes was compared for determining the botanical origin of the honey samples. The electrodes of titanium dioxide, zinc oxide, and silver were more useful, as the results obtained with these electrodes showed that it was achieved a better classification of honey according to its botanical origin. The comparison of the results of the electronic voltammetric tongue technique with those obtained by melissopalynological analysis showed that the technique was able to accurately classify 92.7% of the original grouped cases. The similarity of results confirmed the ability of the electronic voltammetric tongue technique to perform a rapid characterization of honey samples, which complements its advantages of being an easy-to-use and cheap method of analysis.

Triangular Test of Amanita Mushrooms by Using Electronic Nose and Sensory Panel

This work aims to advance understanding of the differentiation of mushroom species through electronic devices that use sensors of various technologies and techniques for pattern recognition, comparing mainly volatile substances that emanate from them. In this first phase, the capacity of human olfaction to differentiate between the smell released by different wild mushrooms of the genus Amanita was analyzed by means of a triangular sensory test, comparing later the data to those obtained for the same samples with an electronic nose in a similar test. The results, still very preliminary, encourage imagining the wide application that these techniques will have and the feedback that this application can suppose for the training of the sense of human olfaction.

Beer Molecules and Its Sensory and Biological Properties: A Review

The production and consumption of beer plays a significant role in the social, political, and economic activities of many societies. During brewing fermentation step, many volatile and phenolic compounds are produced. They bring several organoleptic characteristics to beer and also provide an identity for regional producers. In this review, the beer compounds synthesis, and their role in the chemical and sensory properties of craft beers, and potential health benefits are described. This review also describes the importance of fermentation for the brewing process, since alcohol and many volatile esters are produced and metabolized in this step, thus requiring strict control. Phenolic compounds are also present in beer and are important for human health since it was proved that many of them have antitumor and antioxidant activities, which provides valuable data for moderate dietary beer inclusion studies.

Application of Electronic Nose Systems on Animal-Source Food

Electronic nose, which is designed to perceive artificially the odour-active molecules in a sample headspace, has seen an increased use in the food industry as a rapid and reliable tool for quality assessment, classification, and authentication of several food items. The use of chemometrics and pattern recognition methods, together with gas sensors, emerged to be a very powerful analytical approach. In this chapter, an overview of the recent achievements in the field of electronic nose applications on animal-source food is given. Moreover, the authors deal with the recent research trends to overcome the actual sensor shortcomings, including sensor fusion techniques and their applications to evaluate animal-source foods and novel electronic nose systems.

Efficacy of a titanium dioxide nanoparticles - based indoor anti-odor product as assessed by electronic nose and gaschromatography-mass spectrometry

Indoor air pollutants and odorants may have psychological and physical impact on exposed individuals and the unpleasant room air is considered as one of the factors associated with sick building syndrome comprising general symptoms such as headache and lethargy. Approaches for improving the quality of indoor air are thus important as support for human health and well-being. Photo-oxidation catalyzed by titanium dioxide (TiO₂), is one of the methods used for elimination of volatile organic compounds, which are the cause of odor nuisance in indoor and outdoor air. In the present investigation, the efficacy of an experimental anti-odor air freshener based on TiO₂ nanoparticles was estimated by testing its ability in removing from a small air chamber (200mL) the odor of triethylamine solutions (50μL at concentrations between 0.700 to 700mM), used as a model volatile molecule for simulating fish-like unpleasant indoor environment. The evaluation was performed by electronic nose which provided a holistic and objective data on the efficacy of the product, demonstrating that the effects of triethylamine even at the highest tested concentrations can be completely removed by application of 3.0g of the product at 25% TiO₂ nanoparticles concentration. The obtained results were confirmed by gaschromatography-mass spectrometry (GC-MS) analysis addressed to the quantitative determination of residual triethylamine in the environment after treatment by the anti-odor product.

Application of E-tongue, E-nose, and MS-E-nose for discriminating aged vinegars based on taste and aroma profiles

The combined approach of E-senses was undertaken to discriminate the taste and aroma profiles of aged vinegars, including Chinese Shanxi extra aged vinegar (EX, 5-8 years), Japanese black vinegar (BL, 1-5 years), and Italian balsamic vinegar (BA, 8-25 years). The principal component analysis plot for E-tongue revealed that EX, BL, and BA formed individual groups with clear distinctions. The volatile compounds detected in E-nose based on Kovats indices represented that a major component in all vinegars was matched to acetic acid, which showed a strong relationship with the aging period (R=0.8186-0.9998). The discriminant function analysis plot accompanied by the MS-E-nose indicated that more volatiles were produced during prolonged aging in cereal vinegar, whereas the aging process degraded volatile constituents in fruit vinegar. Categorization with respect to aging years was possible using both E-noses. The approach using E-senses indicated a better discrimination for distinguishing the complex sensory information in aged vinegars.

Characteristics of compounds in hops using cyclic voltammetry, UV-VIS, FTIR and GC-MS analysis

The article presents the antioxidant properties of the extracts of hop EI and EII, by the electrochemical methods on a platinum electrode and comparative analysis of the composition of the extracts of hops using UV-VIS, FTIR and GC-MS methods. The hops extract EI, was obtained from the waste of the hops cone. The hops extract EII, was obtained from the hops cone itself. Hops contain a wide range of polyphenolic compounds with antioxidant properties divided in various chemical classes. Flavonoids and other polyphenolic compounds contained in hops show antioxidant capacity because of the presence of hydroxyl groups in various configurations and numbers within their molecules. The electrochemical properties and antioxidant capacity of hop samples were determined to select the most effective antioxidant. Based on the cyclic and pulse voltammograms, it was observed that hop extract EI contains polyphenols that are oxidised at a less positive potential than extract EII, i.e., it shows better antioxidant capacity. From the analysis of the UV-VIS and FTIR spectra and the GC-MS analysis, it was observed that extract EI contains less phenyl compounds than EII. In addition to flavonoids, EII contains hop acids and chlorophyll. The solutions of hop extracts show very good antioxidant capacities; therefore, they can effectively inhibit or slow negative oxidation reactions and scavenge free radicals and reactive oxygen species (ROS).

On-line monitoring of food fermentation processes using electronic noses and electronic tongues: a review

Fermentation processes are often sensitive to even slight changes of conditions that may result in unacceptable end-product quality. Thus, close follow-up of this type of processes is critical for detecting unfavorable deviations as early as possible in order to save downtime, materials and resources. Nevertheless the use of traditional analytical techniques is often hindered by the need for expensive instrumentation and experienced operators and complex sample preparation. In this sense, one of the most promising ways of developing rapid and relatively inexpensive methods for quality control in fermentation processes is the use of chemical multisensor systems. In this work we present an overview of the most important contributions dealing with the monitoring of fermentation processes using electronic noses and electronic tongues. After a brief description of the fundamentals of both types of devices, the different approaches are critically commented, their strengths and weaknesses being highlighted. Finally, future trends in this field are also mentioned in the last section of the article.