Available online at www.sciencedirect.com ScienceDirect Procedia Engineering 168 (2016) 460 – 464 30th Eurosensors Conference, EUROSENSORS 2016 Quality Evaluation of Parmigiano Reggiano Cheese by a Novel Nanowire Device S3 and Evaluation of the VOCs Profile M P Bhandaria,b, E Núñez Carmonaa,b,*, V Galstyana,b, V Sberveglieria b a Sensor Laboratory, CNR, National Institute of Optics (INO), Via Valotti 9, 25133 Brescia, Italy Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy Abstract A novel nanowire-based sensor device is presented for the quality evaluation of the Italian Parmigiano Reggiano (PR) cheese As a Protected Designation of Origin (PDO) trademark product, the cheese should follow stringent manufacturing guidelines and must exhibit the representative aromatic volatile organic compounds (VOCs) biomarkers and sensory profile Any alteration in these features indicates an adulteration of the product as many low quality and substandard PR cheeses are widely available in the market Different types of grated cheese samples were analyzed and the VOCs were characterized by evaluating the samples with the portable sensor device S3 and Gas Chromatography–Mass Spectrometry technique The ability of S3 device to distinguish the cheese quality demonstrates its suitability for monitoring the quality control and authenticity of PR cheese © Published by Elsevier Ltd This © 2016 2016The TheAuthors Authors Published by Elsevier Ltd.is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the organizing committee of the 30th Eurosensors Conference Peer-review under responsibility of the organizing committee of the 30th Eurosensors Conference Keywords: electronic nose; nanowire gas sensor; Parmigiano Reggiano; cheese quality; GC-MS-SPME; VOCs Introduction Parmigiano Reggiano is the most appreciated Italian cheese throughout the world Its rich flavor, high nutritional value, historical background and strict manufacturing procedures make it very expensive and thus has earned the nickname in the dairy industry, ‘The king of cheeses’ The authentication of PDO cheeses is an important issue because consumers are becoming increasingly aware of the quality and origin of foods [1] The higher price of PR has encouraged more frequent counterfeiting and imitation, so it is crucial to find an analytical method in order to * Corresponding author Tel.: +39-388-633-3180 E-mail address: e.nunezcarmona@unibs.it 1877-7058 © 2016 The Authors Published by Elsevier Ltd This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the organizing committee of the 30th Eurosensors Conference doi:10.1016/j.proeng.2016.11.126 M.P Bhandari et al / Procedia Engineering 168 (2016) 460 – 464 461 protect it against mislabeling In addition, the aroma compounds and volatile profile of the cheese contribute to the distinct sensory characteristics and biochemical properties of the cheese [2] Technological advances have made it rather easy to detect fraudulent activities in food industry In recent years, sensors and electronic noses have been successfully applied in cheese quality control, aroma and odor detection, microbial analysis, authenticity assessment, as well as other aspects of manufacturing [3] However, they are not only expensive and complex but also fairly time-consuming The present study is intended to illustrate the use of a novel nanowire sensor device Small Sensors System (S3) to determine the quality of grated PR cheese and evaluate its odor-active VOCs fingerprint The system has been designed to gather a greater amount of information through a user-friendly control panel It consists of a series of gas sensors, flow sensors, temperature and humidity sensors and actuators (valves, pumps) all enclosed in a portable interface Zinc and Tin oxide crystalline nanowires have been fabricated and incorporated in the S3 sensor network These nanowires enhance the sensing performance of the sensor device [4] Experimental 2.1 S3 device and nanowire technology The nanowire sensor device S3 was designed and built at SENSOR laboratory, Brescia, Italy The excellent characteristics of metal oxide nanowires in terms of sensitivity, stability, low power dissipation and content production costs allowed their use for the manufacture of S3 as a gas detection equipment The fabrication of nanostructures has enabled to achieve a remarkable degree of miniaturization of components that implement the S3 device It is equipped with six metal oxide semiconductor gas sensors, three of them prepared with nanowire technology [5] and the other three with RGTO thin film technology [6] Two of the three nanowires in the array are ZnO sensors with different operating temperatures and the third one is a SnO2 sensor The instrument was provided with an autosampler headspace system HT280T (HTA srl, Brescia, Italy), supporting a 40 loading sites carousel and a shaking oven to equilibrate the sample headspace Figure depicts the layout of the S3 device together with a schematic sketch of the conductometric substrate and SEM images of the nanowires used Fig (a) Photograph of the portable S3 sensor device; (b) Left: Structure of the conductometric device Alumina substrate is in white color in the middle, TiW pads are in brown, platinum heater and contacts are in metallic gray SEM images of Tin (center) and Zinc (right) oxide nanowires 2.2 Samples preparation A total of 20 PR cheese samples from certified origin and with a good, flat and bad organoleptic quality as classified previously by an official panel of judges were provided by Parmigiano Reggiano Cheese Consortium 462 M.P Bhandari et al / Procedia Engineering 168 (2016) 460 – 464 (CFPR), Reggio Emilia, Italy gm of grated cheese was placed in a 20 ml chromatographic vial Subsequently all the vials containing different samples were covered with Silicon-PTFE septum, crimped with an aluminium crimp and then subjected to analysis 2.3 GC-MS analysis GC-MS analysis was carried out on a Shimadzu Gas Chromatograph GC2010 PLUS (Kyoto, KYT, Japan) coupled to a Shimadzu single quadrupole Mass Spectrometer MS-QP2010 (Kyoto, KYT, Japan) ultra and a HT280T autosampler that allowed SPME analysis A DVB/carboxen/PDMS stable flex (50/30 ȝm) (Supelco Co Bellefonte, PA, USA) SPME fiber was used to extract the volatile compounds of the cheese samples which were separated by a low-polarity capillary column (DB-WAX, Agilent Technologies, Santa Clara, CA, USA) The chromatogram was recorded with the following temperature program: 40°C held for min, linear gradient 4°C/min up to 190°C and held for min, followed by a rise from 190°C to 210°C at 5°C/min Results and discussion The explorative data analysis was performed by Principal Component Analysis (PCA), operated with Nose Pattern Editor software and data were processed by EDA software developed in MATLAB at SENSOR laboratory PCA score plot (Figure 2) obtained from S3 analysis showed a clear separation among the good, flat and bad quality cheese samples The instrument was therefore able to discriminate the bad samples from the good and the flat ones The bad samples are all grouped in the same cluster (black) while most of the flat samples overlapped with the good samples, so they are grouped together in the same graph area and within the same cluster (blue) In general, good and flat samples were similar Hence, there was a clear distinction in the flavor profiles between the good and bad samples, in a satisfactory correlation with GC-MS results Fig PCA score plot showing the clusters formed by bad, flat and good cheese samples represented by black stars, green dots and blue circles respectively; PC1=53.73%, PC2=26.30% and PC3=9.23% M.P Bhandari et al / Procedia Engineering 168 (2016) 460 – 464 The GC-MS analysis in Figure indicated both qualitative and quantitative differences between the volatile headspace composition of different classes of samples The most abundant volatile compounds found were alcohols, aldehydes, ketones, esters, lactones, alkaline compounds, hydrocarbons, free fatty acids, amines and pyrazines Butanoic, hexanoic, octanoic and decanoic acids, ethyl butanoate, ethyl hexanoate, ethyl octanoate, 2-heptanone, 2nonanone, 3-methylbutanal, acetic acid, benzeneacetaldehyde and furfural are the major compounds that impart characteristic flavor and aroma to PR cheese and also provide knowledge about quality and safety of the product, acting sometimes as an indicator of processing mistake as well Fig.3 Histogram obtained from GC-MS analysis showing the volatile organic compounds from good (red) and bad (blue) Parmigiano Reggiano cheese samples Conclusion The ability to distinguish PR cheese quality by an easy-to-use, rapid, economic, portable, non-destructive and low power consuming S3 sensor device is crucial as it can be utilized to validate if a given sample is according to law and standards in order to assess fraudulent or imitative production The obtained results showed that the nanowire based S3 device represents a promising tool for the quality control and authenticity evaluation of grated PR cheese To further elucidate the work, we propose to develop S3 on an industrial scale for cheese-chain productions and also introduce it in the wireless mobile systems Acknowledgements The authors thank Parmigiano Reggiano Cheese Consortium (CFPR), Reggio Emilia, Italy for providing the cheese samples References [1] A Caligiani, M Nocetti, V Lolli, A Marseglia, G Palla, Development of a quantitative GC-MS method for the detection of cyclopropane fatty acids in cheese as new molecular markers for Parmigiano Reggiano authentication, J Agric Food Chem., 2016, 64(20), 4158-4164 [2] V Sberveglieri, Validation of Parmigiano Reggiano cheese aroma authenticity, categorized through the use of an array of semiconductors nanowire device (S3), Materials, 2016, 9(2), 81 463 464 M.P Bhandari et al / Procedia Engineering 168 (2016) 460 – 464 [3] V Sberveglieri, E.N Carmona, E Comini, A Ponzoni, D Zappa, O Pirrotta, A Pulvirenti, A novel electronic nose as adaptable device to judge microbiological quality and safety in foodstuff, Biomed Res Int., 2014, 2014, 529519 [4] A Ponzoni, D Zappa, E Comini, V Sberveglieri, G Faglia, G Sberveglieri, Metal oxide nanowire gas sensors: application of conductometric and surface ionization architectures Chem Eng Trans., 2012, 30, 31-36 [5] G Sberveglieri, I Concina, E Comini, M Falasconi, M Ferroni, V Sberveglieri, Synthesis and integration of tin oxide nanowires into an electronic nose, Vacuum, 2012, 86(5), 532-535 [6] G Sberveglieri, G Faglia, S Groppelli, P Nelli, A Camanzi, A new technique for growing large surface-area SnO2 thin-film (RGTO technique), Semiconductor Science and Technology, 1990, 5(12), 123-1233