Search Results (53)

Strawberry leaf extract (SLE) was used in dry fermented sausages, “Salchichón”, to enrich them with antioxidants. The effect of SLE on various characteristics was monitored during ripening and storage. SLE had a slight effect on microbiological characteristics; however, the pH after 3, 14, and 21 days was slightly lower (4.51–4.55) in the samples with higher SLE concentration (0.5% + 1% dextrose). Peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) values of sausages with SLE and with ascorbic acid (reference antioxidant), at the end of ripening, were similar. SLE acted as a pro-oxidant when the sausage was stored in the light; however, it showed antioxidant activity in the dark and at 50 °C storage conditions. Higher extract concentration reduced redness a* value and increased yellowness b* value in the CIELab colour system. Addition of SLE to dry fermented sausages has no negative effect on the ripening process; however, storage conditions of the final product should be carefully controlled. Sensory analysis of the final product showed that SLE imparts a recognisable herbal odour; however, it did not reduce the overall product acceptability. It may be concluded that SLE may be a promising ingredient for increasing the nutritional quality of fermented sausages. Full article

Background: In response to the growing demand for the real-time, in-field characterization of odorous anthropogenic emissions, this study develops and uses a MEMS-based micropacked thermal desorption Gas Chromatography system coupled with a PhotoIonization Detector (GC/PID) for Hot Mix Asphalt (HMA) plant emissions. Methods: The innovative portable device, Pyxis GC, enables the high-sensitivity profiling of Volatile Organic Compounds (VOCs), particularly aldehydes and ketones, with sub-ppb detection limits using ambient air as the carrier gas. A comprehensive experimental design optimized the preconcentration parameters, resulting in an efficient, green analytical method evaluated via the Green Analytical Procedure Index (GAPI). Sorbent comparison showed quinoxaline-bridged cavitands outperform the conventional materials. Results and conclusions: The method was successfully deployed on site for source-specific sampling at an HMA plant, generating robust emission fingerprints. To assess environmental impact, a Generalized Additive Model (GAM) was developed, incorporating the process temperature and Sum of Odour Activity Values (SOAV) to predict odour concentrations. The model revealed a significant non-linear influence of temperature on emissions and validated its predictive capability despite the limited sample size. This integrated analytical–statistical approach demonstrates the utility of MEMS technology for real-time air quality assessment and odour dispersion modelling, offering a powerful tool for environmental monitoring and regulatory compliance. Full article

The odour quality of atmospheric air plays an important role in the comfort of life and human health. Odours can originate from various sources, including municipal facilities, the agricultural and food sectors or industrial plants. A holistic approach to reducing the formation and emission of odorous substances should therefore include the development of odour-neutral process solutions, deodorisation techniques and analytics to measure and monitoring such pollutants in the atmosphere. The implementation of appropriate measures in these three areas can enable the effective management and control of odour emissions. The aim of the work is to carry out a comparative analysis of current methods for measuring the content of odorous substances in the air and for monitoring this type of pollutant. The characterisation of existing solutions carried out became the basis for determining the strengths and weaknesses of the applied protocols and indicating the directions for their further development and improvement. Full article

The final stage of green waste treatment typically occurs in composting plants, where waste is biologically stabilised through the activity of microorganisms. The composting process is accompanied by the emission of volatile organic compounds responsible for odour perception. Such nuisance odours are commonly regarded as atmospheric air pollutants and are subject to monitoring and legal regulation. Olfactometry remains the standard method for quantifying odours. Unfortunately, due to its dependence on human evaluators, it is often regarded as both labour-intensive and costly. Electronic noses are an emerging measurement method that could be used for such applications. This manuscript reports experimental measurements that were carried out at a composting facility specialising in the processing of biodegradable materials. VOC concentration was measured by the TSI OmniTrak™ Solution. The efficiency of the deodourisation process was evaluated by means of field olfactometry. A gas sensor array of a PEN3 electronic nose was used for the on-site measurements of emitted gas characteristics. A strong correlation between measurements by the three distinct techniques was confirmed. Three different phases of the composting process could be distinguished in the collected results. Full article

The natural process of lake and reservoir eutrophication through nutrient accumulation within sediments has been accelerated through anthropogenic sources of nitrogen and, especially, phosphorus (P). Stored nutrients can result in significant internal loading (during periods of low sediment redox potential or elevated pH), which may drive poor water quality despite best practices in catchment management. Internal P loading can promote proliferation of cyanobacterial and algal taxa responsible for harmful algal blooms (HABs), as well as taste and odour (T&O) and cyanotoxin events. Here, we investigate the sediment and water column P content of eight reservoirs by analysing iron-bound (Fe-P), calcium-bound (Ca-P), and labile P fractions. We find that all but one reservoir demonstrated high iron (Fe) content (27–52 g Fe/kg sediment), suggesting a high Fe-P binding capacity and hence a potentially high susceptibility to redox-mediated internal loading. However, we found no correlation between Fe-P and Fe content in sediments, suggesting the Fe pool was not saturated with P and thus has capacity for further storage. All sites had low levels of labile P (up to 0.14 mg P-PO₄/g dry sediment), with the highest pool of P being Ca-bound, which would be expected based on catchment geology and the presence of Ca-minerals which bind P. Currently, within industry, emphasis falls on controlling the external loading of nutrients from the surrounding catchment, often ignoring the critical role of internal loading. However, here, we demonstrate the need to continually monitor sediment P content and potential internal loading as part of the standard monitoring regime used by water companies to inform reservoir management strategies. Full article

Composting is a key component of sustainable development strategies, as it supports ecological waste management, minimises the impact of human activities on the environment, and promotes the efficient use of natural resources. Reducing the generation of additional waste—as “recirculation” of composted waste—is also an important indicator of sustainability processes. The intermediate fraction (IF) is the material within the 10 mm to 60–90 mm range. It can be incorporated into composting materials to enhance the composting process. Maintaining an appropriate proportion of this fraction in the compost mixture is crucial for its practical use. This research examined the impact of adding the IF to composting on reducing the release of odorous substances. Additionally, it aimed to optimise the composting process by effectively managing the fraction. Optimisation sought to achieve high-quality compost, minimise odour emissions, and enhance the overall efficiency of the process. The study enabled the selection of the optimal variant—adding 9% of IF with inoculum—considering both ammonia emissions and odour impact. This variant yielded 13% less ammonia and 37% less odour than the variant without additives. This included identifying the intermediate fraction’s ideal proportion and adding pre-composted waste to compost piles. Full article

Biofilms in drinking water systems hosting diverse microbial communities are potential sources of opportunistic pathogens and taste/odour complaints. Domestic distribution networks are especially prone to biofilm formation due to high surface-to-volume ratio, elevated ambient temperature and intermittent use. Bacterial community diversity and determinants of community structure were investigated in two buildings using a purpose-designed in situ device containing stainless steel and polypropylene coupons and an online biofilm sensor. Next generation sequencing and scanning electron microscopy revealed increasing diversity and complexity over time. Initial biofilms were dominated by Proteobacteria (86–99%, primarily Burkholderiales and Sphingomonadales, core genera Aquabacterium and Blastomonas in month 1, and Rhizobiales in month 3), with an increasing ratio of Actinbacteriota (51–65%, mainly Corynebacteriales) and Bacteroidota (3–5%) by month 6. The impact of the sampling location was secondary to biofilm age in determining microbial diversity, and within-building variation was comparable to differences between facilities. The coupon material had a negligible effect on community structure. Real-time monitoring by online sensors did not yield interpretable data. Important nosocomial pathogens (Mycobacterium, Legionella, Methylobacterium, Bosea) were detected in the biofilm samples that were absent in bulk water, implying that water monitoring alone is not sufficient for estimating the risk of water-related pathogens. Full article

This study evaluated the reliability of an electronic nose in monitoring odour concentration near a wastewater treatment plant and examined the correlation between four sensor readings and odour intensity. The electronic nose chemical sensors are related to the concentration of the following chemical species: two values for the concentration of VOCs recorded via the PID sensor (VPID) and the EC sensor (VEC), and concentrations of sulfuric acid (VH₂S) and benzene (VC₆H₆). Using Random Forest and least squares regression analysis, the study identifies VH₂S and VC₆H₆ as key contributors to odour concentration (C^c_OD). Three Random Forest models (RF0, RF1, RF2), with different characteristics for splitting between the test set and the training set, were tested, with RF1 showing superior predictive performance due to its training approach. All models highlighted VH₂S and VC₆H₆ as significant predictors, while VPID and VEC had less influence. A significant correlation between odour concentration and specific chemical sensor readings was found, particularly for VH₂S and VC₆H₆. However, predicting odour concentrations below 1000 ou_E/m³ proved challenging. Linear regression further confirmed the importance of VH₂S and VC₆H₆, with a moderate R-squared value of 0.70, explaining 70% of the variability in odour concentration. The study demonstrated the effectiveness of combining Random Forest and least squares regression for robust and interpretable results. Future research should focus on expanding the dataset and incorporating additional variables to enhance model accuracy. The findings underscore the necessity of specific sensor training and standardised procedures for accurate odour monitoring and characterisation. Full article

Exposure to high concentrations of odours can result in health effects associated with direct health risks and irritation from nuisance. This investigation aimed to correlate aspects of the waste composting process with the emission levels of malodourous compounds. An essential optimisation criterion is the reduction of negative environmental impacts, particularly odour emissions. This study characterises odour concentration variations across various technological variants over different weeks of the composting process. A secondary objective is evaluating the efficacy of these variants, which differ in inoculation substances and compost heap composition. Olfactometric analyses were conducted using portable field olfactometers, enabling precise dilutions by mixing contaminated and purified air. The primary aim was to examine the correlation between selected odour parameters, determined via sensory analysis, and ammonia concentration during different composting weeks. Ammonia levels were measured using an RAE electrochemical sensor. Research shows that odour concentration is a significant indicator of compost maturity. In situ, olfactometric testing can effectively monitor the aerobic stabilisation process alone or with other methods. The most effective technological solution was identified by combining olfactometric and ammonia measurements and monitoring composting parameters, ensuring minimal odour emissions and the safety of employees and nearby residents. Full article

Waste treatment plants (WTPs) often generate odours that may cause nuisance to citizens living nearby. In general, people are becoming more sensitive to environmental issues, and particularly to odour pollution. Instrumental Odour Monitoring Systems (IOMSs) represent an emerging tool for continuous odour measurement and real-time identification of odour peaks, which can provide useful information about the process operation and indicate the occurrence of anomalous conditions likely to cause odour events in the surrounding territories. This paper describes the implementation of two IOMSs at the fenceline of a WTP, focusing on the definition of a specific experimental protocol and data processing procedure for dealing with the interferences of humidity and temperature affecting sensors’ responses. Different approaches for data processing were compared and the optimal one was selected based on field performance testing. The humidity compensation model developed proved to be effective, bringing the IOMS classification accuracy above 95%. Also, the adoption of a class-specific regression model compared to a global regression model resulted in an odour quantification capability comparable with those of the reference method (i.e., dynamic olfactometry). Lastly, the validated models were used to process the monitoring data over a period of about one year. Full article

Understanding the stimuli used by insect pests to find their food plants can be a first step towards manipulating their behaviour and, thus, controlling them. We investigated the responses of the sugar beet weevil Asproparthenis punctiventris (Coleoptera: Curculionidae) to the volatile leaf odours of its food plants, including Beta vulgaris subsp. vulgaris (Altissima and Cicla groups), Atriplex hortensis, Chenopodium album, and Amaranthus retroflexus, in a four-arm olfactometer. A bioassay procedure was developed, and the frequency of visits and time spent by adult weevils in the quadrant of the olfactometer with leaf volatiles was recorded, as was their first choice of quadrant. Females and males were equally attracted to the leaf odours of young B. vulgaris subsp. vulgaris plants, i.e., sugar beet and chard, as indicated by the overall picture of the behavioural parameters analysed. Males, but not females, responded positively to the leaf odour of the garden orache (A. hortensis), and no response was observed when the weevils were tested with the leaf odours of fat hen (C. album) or common amaranth (A. retroflexus). These results suggest that A. punctiventris uses leaf odours to locate sugar beet and other food plants. Knowledge of the olfactory responses of this pest can provide a basis for improved monitoring or mass trapping strategies. Full article

This work proposes an electronic nose (e-nose) system based on resistive gas sensors to predict the cooking evolution of different types of bread. The e-nose includes six metal-oxide semiconductor (MOS) gas sensors, a low-noise electronic system for signal conditioning and data acquisition, and a classification algorithm for real-time detection of the cooking stage. Baking tests with five different recipes were carried out, and the system performances were evaluated by a panel of tasters, obtaining a -88% accuracy for the automatic detection of cooking time. Full article

The realisation of an electronic nose network for the monitoring of the odour concentrations at the fenceline of a waste treatment plant has been investigated. One of the main challenges for instrumental environmental monitoring concerns the interference of the daily variability of humidity and temperature of the ambient air to which sensors are exposed. In this study, we propose a solution to overcome this problem, implementing a specific normalisation pretreatment into the data processing procedure. The preliminary results obtained show a better classification and quantification performance whenever humidity model compensation is applied. Full article

Generating rapid, easy-to-interpret community data for drinking reservoirs as a means of tackling water quality management is of increasing demand within the water industry. Taste and odour (T&O) is one of many increasing concerns to water companies worldwide, incurring huge costs as customer complaints accumulate and additional treatment and resource management are required. However, there remains a two-fold issue in addressing T&O management: firstly, predicting the initial onset of a T&O event relies on a highly complex understanding of environmental considerations and their interaction with T&O-related taxa, and secondly, there remains a lag between the notification of a T&O event and the resolution of the issue by reservoir management staff. This is partly due to slow, low-resolution methods of detecting and reliably identifying problem taxa in samples. These methods are unable to provide information on the huge plethora of taxa related to T&O metabolite production and often cannot provide data in a timely enough manner for an opportune management response. This means the water industry is often forced to use a reactive, rather than proactive, approach to water quality monitoring. Here, we present methods for implementing a high-throughput sequencing approach to monitoring drinking reservoirs for water quality and improving the sustainability of water supplies, as well as methods for presenting these data on easy-to-interpret data dashboards that can be updated rapidly as new data are generated. Our methods and dashboarding approaches are currently being trialled and tested within the UK water industry, and so here, we show anonymised examples of those data presentations. We propose that these methods can greatly aid reservoir management teams in their approach to T&O monitoring and can be used to implore more sustainable management pipelines, safeguarding future water sources. Full article

Geosmin and 2-methylisoborneol (MIB) are the most common causes of unpleasant odours in drinking water. A method was proposed to detect and recognise these compounds in water and determine their concentrations. The method utilises commercial solid-state gas sensors and data analysis. Sample preparation plays an important role. The aqueous solution is converted into a gas sample using a specially designed dynamic headspace. The responses of the sensors are recorded during exposure to headspace vapours in a dynamic mode. The best limit of detection for geosmin, LOD = 6.20 µg/L, was attained with a TGS2602 sensor. The best limit of detection for MIB, LOD = 0.52 µg/L, was attained with a TGS826 sensor. Geosmin and MIB recognition was 100% successful based on TGS826 and TGS2602 response classifications. Geosmin and MIB concentrations were effectively determined in solutions containing one or both compounds. The respective mathematical models utilised the responses of TGS826 and TGS2602. The smallest concentration prediction error was RMSE = 2.19 µg/L (for geosmin) and RMSE = 0.33 µg/L (for MIB). The study demonstrated the application potential of non-specific gas sensors for the early warning monitoring of geosmin and MIB presence in water. Further studies are needed to develop a system that can be tested in field conditions. Full article