Electrochemical modification of the redox potential of different milk products and its evolution during storage Arnaud Schreyer a , Michel Britten b,1 , Jean-Marc Chapuzet c,2 , Jean Lessard d,3 , Laurent Bazinet e, ⁎ a Institut des Nutraceutiques et des Aliments Fonctionnels (INAF) and Centre de Recherche en Sciences et Technologies du Lait (STELA), Département des sciences des aliments et de nutrition, Université Laval, Sainte-Foy, Quebec, Canada G1K 7P4 b Food Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, Quebec, Canada J2S 8E3 c Laboratoire de synthèse et d'électrosynthèse organiques, Département de chimie, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1K 2R1 d Laboratoire de synthèse et d'électrosynthèse organiques, Département de chimie, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1K 2R1 e Institut des Nutraceutiques et des Aliments Fonctionnels (INAF) and Centre de Recherche en Sciences et Technologies du Lait (STELA), Département des sciences des aliments et de nutrition, Université Laval, Sainte-Foy, Quebec, Canada G1K 7P4 Received 26 February 2007; accepted 1 July 2007 Abstract Redox potential has applications in the food industry, especially to assess the microbiological and organoleptic qualities of milk. Therefore, electroreduction has also been put forward as a means of inhibiting and/or reducing oxidation phenomena in milk by modifying its redox potential. However, these investigations failed to isolate the components contributing to the value of redox potential of milk. In this study, a series of electrolysis treatments were carried out to determine how the different major components of milk as well as thermal treatment influence the redox potential during and after electroreduction. It was found that the fat and protein content of the milk products, together with the heat treatments applied, have a considerable effect on the redox potential of these milk products after electroreduction. Furthermore, this change in redox potential is only temporary, since the redox potential levels of electroreduced milk products return to positive values after only 4 days of storage. © 2007 Elsevier Ltd. All rights reserved. Keywords: Milk; Electroreduction; Redox potential; Dissolved oxygen; Storage Industrial relevance: The redox potential of milk, widely studied in the past, gives some indications of the oxidative quality and stability of milk. This paper presents an innovative and clean method to control the redox potential of milk products with the use of electrochemistry. The results presented demonstrated the efficiency of electroreduction to reduce the redox potential and dissolved oxygen concentration of four milk products. 1. Introduction According to Nernst (Morris, 2000), oxidation-reduction (redox) potential provides an instantaneous measure between a standard redox potential and the concentration ratio of oxidizers and reducers. Simply stated, redox potential can be used to determine whether a system is in an oxidized or a reduced state. Redox potential has many applications in microbiology, i.e. methylene blue or resazurine test (Jacob, 1979), and is used widely in the food industry, especially in determinations of the microbiological quality of canned foods (Montville & Conway, 1982), beverages (VanStrien, 1987; Vivas, 1999) and milk (Pappas, Voutsinas, & Mallatou, 1989). In the case of milk, redox potential has also been used to assess organoleptic quality (Greenbank, 1940; Swanson & Sommer, 1940; Webb & Hileman, 1937), and it has even been used to detect copper contamination of milk products (Webb & Hileman, 1937). These studies have shown the effect of oxidation-reduction Available online at www.sciencedirect.com Innovative Food Science and Emerging Technologies 9 (2008) 255 – 264 www.elsevier.com/locate/ifset Abbreviations: ORP, oxidation-reduction potential or redox potential; DOC, dissolved oxygen concentration. ⁎ Corresponding author. Tel: +1 418 656 2131x7445; fax: +1 418 656 3353. E-mail addresses: arnaudschreyer@hotmail.com (A. Schreyer), brittenm@agr.gc.ca (M. Britten), Jean-Marc.Chapuzet@USherbrooke.ca (J.-M. Chapuzet), Jean.Lessard@USherbrooke.ca (J. Lessard), Laurent.Bazinet@aln.ulaval.ca (L. Bazinet). 1 Fax: +1 450 773- 8461. 2 Fax: +1 819 821- 8017. 3 Fax: +1 819 821- 8017. 1466-8564/$ - see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.ifset.2007.07.001