Scientific pubblications
Colorimetric Sensor Array for Monitoring, Modelling and Comparing Spoilage Processes of Different Meat and Fish Foods
Authors
Lisa Rita Magnaghi, Federica Capone, Camilla Zanoni, Giancarla Alberti,
Paolo Quadrelli and Raffaela Biesuz
Pubblication
Foods, 9 (2020), 684
Abstract
Meat spoilage is a very complex combination of processes related to bacterial activities. Numerous efforts are underway to develop automated techniques for monitoring this process. We selected a panel of pH indicators and a colourimetric dye, selective for thiols. Embedding these
dyes into an anion exchange cellulose sheets, i.e., the commercial paper sheet known as “Colour Catcher®” commonly used in the washing machine to prevent colour run problems, we obtained an array made of six coloured spots (here named Dye name-CC@). The array, placed over the tray containing a sample of meat or fish (not enriched at any extend with spoilage products), progressively shows a colour change in the six spots. Photos of the array were acquired as a function of time, RGB indices were used to follow the spoilage, Principal Component Analysis to model the data set. We demonstrate that the array allows for the monitoring the overall spoilage process of chicken, beef, pork and fish, obtaining different models that mimic the degradation pathway. The spoilage processes for each kind of food, followed by the array colour evolution, were eventually compared using three-way PCA, which clearly shows same degradation pattern of protein foods, altered only according to the different substrates.
Development of a Dye-Based Device to Assess Poultry Meat Spoilage. Part I: Building and Testing the Sensitive Array
Authors
Lisa Rita Magnaghi, Giancarla Alberti, Paolo Quadrelli and Raffaela Biesuz
Pubblication
Journal of Agricultural and Food Chemistry, 68 (2020), 45, 12702–12709
Abstract
The rationale behind the material and dye selection and the investigation of the properties of a solid-phase sensor array designed for following chicken meat spoilage is presented, having in mind that the final target must be the naked eye identification of the degradation steps. The device is obtained by fixing five acid−base indicators, m-cresol purple (1), o-cresol red (2), bromothymol blue (3), thymol blue (4), and chlorophenol red (5), and a sensing molecule specific for thiols, 5,5′-dithiobis(2-nitrodibenzoic acid), called Ellman’s reagent, (6) on a commercial cellulose-based support. The dimensions of the sensor and the amount of dye sorbed on the solid are carefully studied. The preparation protocol to get reproducible sensing materials is established, based on the kinetic study and the color change investigation. The material stability and the capacity of changing color, according to the acid−base properties of the dyes, are tested. The sources of uncertainty, coming from the technique employed for signal data acquisition and treatment and from the intrinsic variability of the spots based on the commercial support, are established.
The highest variability does not come from photo acquisition by a mobile phone, the effect of the illumination equipment, the partial least-squares (PLS) model employed to assess the amount of dye sorbed into the solid but from the variability of different spots and was found equal to 10%. The uncertainty is adequate for final employment since it is referred to as replicates under different conditions that are definitively judged almost always identical by naked eye evaluation, which is our last target for assessing a change of the colors associated with spoilage.
Development of a Dye-Based Device to Assess the Poultry Meat Spoilage. Part II: Array on Act
Authors
Lisa Rita Magnaghi, Giancarla Alberti, Federica Capone, Camilla Zanoni, Barbara Mannucci, Paolo Quadrelli and Raffaela Biesuz
Pubblication
Journal of Agricultural and Food Chemistry, 68 (2020), 45, 12710–12718
Abstract
This work presents a colorimetric dye-based array for naked-eye detection of chicken meat spoilage. The array is obtained by fixing five acid−base indicators, m-cresol purple (1), o-cresol red (2), bromothymol blue (3), thymol blue (4), and chlorophenol red (5), and a sensing molecule specific for thiols, 5,5′-dithiobis(2-nitrodibenzoic acid), called Ellman’s reagent (6), on a cellulose-based support. The dyes, being permanently charged, are fixed on the support via ion-exchange. The entire degradation process of beast poultry meat, at ambient temperature and in a domestic fridge, is followed by the change of the color of the array, placed in the headspace over the meat samples. The device is set after selection of the most suitable starting form, which could be the acidic or the basic color of indicators, being the proper dye concentration and the dimension of the spots already established. Basing on sensors colors, we identified three levels of the degradation process of chicken meat, named SAFE, WARNING, and HAZARD.
By instrumental analysis, we demonstrated that sensors response was correlated to volatile organic compounds (VOCs) composition in the headspace and, thus, to meat spoilage progress. We demonstrated that biogenic amines (BAs), commonly considered a critical spoilage marker, are indeed produced into the samples but never present in the headspace, even in traces, during the investigated time-lapse. The VOC evolution nevertheless allows one to assign the sample as WARNING and further HAZARD. Some indicators turned out to be more informative than others, and the best candidates for a future industrial application resulted in a bromothymol blue (3)-, chlorophenol red (5)-, and Ellman’s reagent (6)-based array.
Naked-Eye Food Freshness Detection: Innovative Polymeric Optode for High-Protein Food Spoilage Monitoring
Authors
Lisa Rita Magnaghi, Giancarla Alberti, Chiara Milanese, Paolo Quadrelli and Raffaela Biesuz
Pubblication
ACS Food Science & Technology, 1 (2021), 2, 165-175
Abstract
This work aims to develop an efficient sensing device to detect milk freshness when stored at typical home conditions. The synthesis of the pH-sensitive optode array, the experimental setup for milk freshness monitoring, and the optode array images acquisition procedure are presented. The employment of various chemometric tools on optode array RGB triplets to visualize, compare, and predict the spoilage of commercial types of milk is discussed. The conclusions drawn from multivariate analyses on optode colors were confirmed using different independent methods. Despite the apparent simplicity, the here proposed sensing device fulfills the requirements for both consumer-friendly naked-eye analysis and chemometrics-assisted prediction of milk freshness. Furthermore, the application of the sensing device on real milk samples during spoilage at home conditions represents a major step forward in the panorama of freshness indicators for dairy products.
EVOH-Based pH-Sensitive Optode Array and Chemometrics: From Naked-Eye Analysis to Predictive Modeling to Detect Milk Freshness
Authors
Lisa Rita Magnaghi, Federica Capone, Giancarla Alberti, Camilla Zanoni, Barbara Mannucci, Paolo Quadrelli and Raffaela Biesuz
Pubblication
ACS Food Science & Technology, 1 (2021), 5, 819-828
Abstract
This work presents a colorimetric dye-based array for naked-eye detection of chicken meat spoilage. The array is obtained by fixing five acid−base indicators, m-cresol purple (1), o-cresol red (2), bromothymol blue (3), thymol blue (4), and chlorophenol red (5), and a sensing molecule specific for thiols, 5,5′-dithiobis(2-nitrodibenzoic acid), called Ellman’s reagent (6), on a cellulose-based support. The dyes, being permanently charged, are fixed on the support via ion-exchange. The entire degradation process of beast poultry meat, at ambient temperature and in a domestic fridge, is followed by the change of the color of the array, placed in the headspace over the meat samples. The device is set after selection of the most suitable starting form, which could be the acidic or the basic color of indicators, being the proper dye concentration and the dimension of the spots already established. Basing on sensors colors, we identified three levels of the degradation process of chicken meat, named SAFE, WARNING, and HAZARD.
By instrumental analysis, we demonstrated that sensors response was correlated to volatile organic compounds (VOCs) composition in the headspace and, thus, to meat spoilage progress. We demonstrated that biogenic amines (BAs), commonly considered a critical spoilage marker, are indeed produced into the samples but never present in the headspace, even in traces, during the investigated time-lapse. The VOC evolution nevertheless allows one to assign the sample as WARNING and further HAZARD. Some indicators turned out to be more informative than others, and the best candidates for a future industrial application resulted in a bromothymol blue (3)-, chlorophenol red (5)-, and Ellman’s reagent (6)-based array.
Towards intelligent packaging: BCP-EVOH@ optode for milk freshness measurement
Authors
Lisa Rita Magnaghi, Camilla Zanoni, Giancarla Alberti, Paolo Quadrelli and Raffaela Biesuz
Pubblication
Talanta, 241 (2022), 123230
Abstract
Intelligent packaging represents an emerging trend in the food industry, especially for highly perishable foods like milk and dairy products. Despite the apparent simplicity, miniaturized BCP-EVOH@ sensor, made of bromocresol purple (BCP) covalently bound to ethylene-vinyl alcohol (EVOH) copolymer, meets the goal of milk freshness monitoring during chilled storage, allowing both naked-eye evaluation and chemometric-assisted spoilage modelling and measurements.
Freshness Traffic Light for Fish Products: Dual-Optode Label to Monitor Fish Spoilage in Sales Package
Authors
Lisa Rita Magnaghi, Camilla Zanoni, Giancarla Alberti, Paolo Quadrelli and Raffaela Biesuz
Pubblication
ACS Food Science & Technology, 2, 6 (2022), 1030-1038
Abstract
Freshness and safety of fish products alongside the supply chain, from the harvest to the final consumers, represent an increasing concern due to the perishability of these foods. Therefore, there is an urgent need for low-cost, reliable, and easy-to-read devices to monitor fish products’ freshness, directly implemented on sales packages. The here presented device consists of two colorimetric sensor units, in which a pH indicator, o-cresol red, is covalently bound to a plastic support, ethylene vinyl alcohol, and equilibrated at different pHs. The dual-optode label works as a freshness traffic light that turns color according to the spoilage by-products and, thus, the real freshness. The naked-eye readout and the chemometric-assisted spoilage modeling are demonstrated and validated for a panel of fish products, simulating distribution and domestic storage conditions. The sensing performances and the versatility make this dual-optode label an interesting candidate to be implemented as smart labels in packed fish products.
pH-sensitive sensors at work on poultry meat degradation detection: from the lab to the supermarket shelf.
Authors
Lisa Rita Magnaghi, Camilla Zanoni, Elena Bancalari, Jasmine Hadj Saadoun, Giancarla Alberti, Paolo Quadrelli and Raffaela Biesuz
Pubblication
AppliedChem, 2, 3 (2022), 128-141
Abstract
In the last twenty years, the number of publications presenting generalized pH-sensitive devices proposed for food freshness monitoring has been steadily growing, but to date, none of them have succeeded in exiting the laboratory and reaching the supermarket shelf. To reach this scope, we developed a large-scale applicable pH-sensitive sensor array to monitor perishable foods’ degradation. We ensured freshness monitoring in domestic conditions, using sales packages and during chilled storage, by simple naked-eye readout and multivariate imaging analysis, and we fully corroborated the device by (i) projection of unknown independent samples in the PCA model, (ii) TVB-N quantification and (iii) microbiological assay. The choice of commercial and cheap dye and polymeric support already employed in food packaging ensures the low-cost and scalability of the device and the promising results obtained make this device an eligible candidate for large-scale implementation.