Research note Evaluation of lacquered tinplated cans containing octopus in brine by employing X-ray microanalysis and electrochemical impedance spectroscopy Antonios V. Pournaras, Mamas I. Prodromidis, Alexandros P. Katsoulidis, Anastasia V. Badeka, Dimitrios Georgantelis, Michael G. Kontominas * Department of Chemistry, University of Ioannina, Ioannina 45110, Greece Received 23 March 2007; received in revised form 28 September 2007; accepted 30 September 2007 Available online 17 October 2007 Abstract Investigation of metal can discoloration, lacquer adhesion failure and side seam steel corrosion in tin plated cans containing cooked octopus in brine was evaluated with X-ray microanalysis (energy dispersive X-ray spectroscopy, EDS) and electrochemical impedance spectroscopy (EIS). The effectiveness of EDS to analyze corrosion defects in metal food containers has been proven already in previous studies carried out in our laboratory. Complementary and/or alternative to sophisticated surface analysis methods, which require advanced and expensive instrumentation, simple and inexpensive quality tests based on EIS were also performed and results are dis- cussed. Obvious alterations of the electrochemical properties of corroded and non-corroded samples (internal can walls and side seam) used as working electrodes in a common three-electrode compartment electrochemical cell can be used for rapid and simple evaluation of corrosion defects in tinplated food cans. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: X-ray microanalysis; Electrochemical impedance spectroscopy; Discoloration; Can corrosion 1. Introduction A large portion of processed food products including meat and fish products, soups, fruit and fruit juices, con- densed milk etc. reach the consumer annually in the form of canned products (Kraus and Tarulis, 1997; Robertson, 1993). Out of the several millions of canned products reaching the consumer worldwide, the overwhelming majority of which are of excellent quality, metal containers occasionally develop integrity problems which can lead to early failure through corrosion, loss of seal integrity, dis- coloration development, all resulting to canned product rejection by the consumer (Charbonneau, 1997). Can integrity problems reported in the literature include: stress corrosion cracking (SCC) involving corro- sion at stressed areas of the container, sulfide black corro- sion involving the formation of a black body and occasionally discoloration on the product surface, pitting corrosion involving rapid iron dissolution at fractures or pores in the organic coating leading to product blackening, external (filiform) corrosion involving the formation of rust on the external surface of metal container due to scratch defects and enamel adhesion failure involving the chemistry of the organic coating, the application procedure of the coating or the nature of the metal substrate (Charbonneau, 1997; Resnik, 1997). Tinplate corrosion depends on many factors including can material (tin coated steel, tin free steel), nature of the organic coating (epoxy, polyester, acrylic resins), enamel properties (adhesion, porosity and corrosion resistance), nature of the contacting medium (aqueous, fatty foodstuffs) 0260-8774/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2007.09.034 * Corresponding author. Tel.: +30 2651098342; fax: +30 2651098795. E-mail address: mkontomi@cc.uoi.gr (M.G. Kontominas). www.elsevier.com/locate/jfoodeng Available online at www.sciencedirect.com Journal of Food Engineering 86 (2008) 460–464