Development of methodology for assessment of shelf-life of fried potato wedges using electronic noses: Sensor screening by fuzzy logic analysis Dipan Chatterjee a , Paramita Bhattacharjee a,⇑ , Nabarun Bhattacharyya b a Department of Food Technology and Biochemical Engineering, Jadavpur University, Kolkata 700 032, India b Centre for Development of Advanced Computing (C-DAC), E-2/1, Block – GP, Sector – V, Salt Lake, Kolkata 700 091, India article info Article history: Received 4 September 2013 Received in revised form 29 January 2014 Accepted 12 February 2014 Available online 20 February 2014 Keywords: Electronic nose Fried food products Shelf-life study Fuzzy logic analysis Mahalanobis distance abstract Development of a methodology for rapid assessment of shelf-life of fried potato wedges were carried out using electronic noses (e-noses) with metal oxide gas sensors. Fuzzy logic analysis was applied for the first time for screening the sensors and it was found that four sensors were more specific for detecting volatile organic compounds from fried potato wedges. Data obtained from these screened sensors concluded that fried potato wedges had shelf-life of 3 days when stored in inert atmosphere of nitrogen in Ziploc pouches at 23 ± 2 °C. Mahalanobis distance method was adopted for quantifying the extent of spoilage and was correlated to peroxide values and free fatty acid content obtained by biochemical assays. Since, this methodology accurately and rapidly predicted the shelf-life of fried potato wedges; it could be also applied for fast and reliable estimation of shelf-life of various fried food products. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Fried potato wedges are globally consumed as a very popular deep fried snack owing to their crisp texture, flavor, color and mouth-feel (Van Loon et al., 2007). However, the major problem encountered with fried potato wedges is during their storage owing to their propensity to deteriorate consequent to microbial infestation and by biochemical reactions, primarily by lipid oxida- tions. These oxidative reactions decrease their nutritional quality with simultaneous generation of potentially toxic products (Nawar, 1997). Currently, global strategic research agenda empha- sizes PAN (Preference, Acceptance and Need) analyses of food products, hallmarked as the key characteristics that lead consumer choices for a given food product (Schweiger, 2013). These charac- teristics are primarily governed by food product formulation and design and also by the product shelf-stability. To ascertain the latter, it is necessary to monitor the spoilage pattern of food products with time (Nawar, 1997). Conventionally, spoilage of lipid-rich products are determined through microbial and biochemical assays, which are time consuming, less reliable and of low sensitivity. Electronic nose (e-nose) technology, which works by mimicking the human olfactory system, is widely used in food industries for effective and convenient process monitoring, shelf-life investigation, freshness evaluation, authenticity assess- ment and quality control for cooking and fermentation processes (Peris and Escuder-Gilabert, 2009; Chatterjee et al., in press). Vin- aixa et al. (2005) used this technology for directly detecting rancid- ity in potato crisps, foregoing the problems associated with conventional biochemical assays. Wide et al. (1997) applied this technology, in fusion with tactile and auditory sensors for studying ageing and quality of potato chips. This work endeavored to extend the application of e-nose technology in detecting spoilage in fried potato wedges, which with their higher oil and moisture content pose additional challenges in data acquisition and analyses. The objective of the current investigation is to develop a methodology to predict the shelf-life of fried potato wedges using an e-nose system, equipped with metal oxide gas sensors which are sensitive towards a wide range of volatile gases. Generally for a particular food system, certain sensors are more specific and sensitive than others. Therefore, it is better to screen the most appropriate sensors for a particular food system for accurate estimation of shelf-lives of foods. It has also been reported by several authors that with large number of sensors, the discrimina- tion indices in principle component analysis are generally poor and better discrimination indices are obtained when number of sensors http://dx.doi.org/10.1016/j.jfoodeng.2014.02.009 0260-8774/Ó 2014 Elsevier Ltd. All rights reserved. Abbreviations: AOAC, Association of Analytical Communities; AR, analytical reagent; C-DAC, Centre for Development of Advanced Computing, Kolkata, India; CFC, chlorofluorocarbon; FFA, free fatty acids; meq, Milliequivalent; PAN, Prefer- ence, Acceptance and Need; PV, peroxide values; TFN, triangular fuzzy number; TOC, total organic carbon; VOCs, volatile organic compounds. ⇑ Corresponding author. Tel./fax: +91 33 2414 6822. E-mail address: pb@ftbe.jdvu.ac.in (P. Bhattacharjee). Journal of Food Engineering 133 (2014) 23–29 Contents lists available at ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng