Applicability of biological time temperature integrators as quality and safety indicators for meat products M. Ellouze a,b, ⁎, J-C. Augustin b a CRYOLOG S.A. Département R&D. 58, Boulevard Gustave Roch, 44261 Nantes, France b Unité MASQ Microbiologie des Aliments – Sécurité et Qualité, Ecole Nationale Vétérinaire d' Alfort, 7, Avenue du Général de Gaulle 94704 Maisons Alfort, France abstract article info Article history: Received 18 September 2009 Received in revised form 4 December 2009 Accepted 9 December 2009 Keywords: Biological TTI Meat products Microbial growth Exposure assessment model Listeria monocytogenes Staphylococcus aureus Salmonella The objective of this study was to evaluate (eO) ® , a biological time temperature integrator (TTI) as a quality and safety indicator for ground beef packed under modified atmosphere and spiced cooked chicken slices packed under modified atmosphere. Storage trials and challenge tests were thus performed on several batches of the studied food to monitor and model the behavior of Listeria monocytogenes, Salmonella, Staphylococcus aureus and the indigenous food flora. Then, two different prototypes of the TTI (eO) ® were set and manufactured according to the studied products shelf lives. The TTI evolution with time at static and dynamic temperatures was monitored and modeled. Finally, exposure assessment models were set and used under several realistic storage profiles to assess the distributions of the concentration of the indigenous food flora and the distributions of the increase in the pathogens populations obtained at the end of the product shelf life or at the end point of the TTI, taking into account the TTIs batch variability. Results showed that in case of poor storage conditions, TTI can reduce the consumer exposure to altered or hazardous foods. © 2009 Elsevier B.V. All rights reserved. 1. Introduction The food law and the recent regulatory changes in the food industry in Europe, emphasize the importance of the development of a structured quality assurance system using the Hazard Analysis Critical Control Point method (HACCP) and Good Manufacturing and Hygiene Practices. Such a system is based on prevention and control all through the manufacturing process rather than on testing and verification of the final products; its application requires a continuous monitoring and control of critical parameters (Taoukis et al., 1999) throughout the manufacturing process not only at the production level but during the entire food chain from production through distribution and storage (Nuin et al., 2008) including domestic storage at the consumer level. However, conditions during transportation and at the retail level are out of manufacturer's direct control (Tsironi et al., 2008). For example, the temperature of storage, which is one of the major factors influencing the rate of microbial development in foods (McMeekin et al., 2008), often deviates from specifications and this is generally recognized by industrialists, retailers and even food authorities (Giannakourou et al., 2005). Time temperature integrators (TTIs) can provide a solution to this issue as they are recognized as cost effective and user friendly devices (Taoukis et al., 1999) to monitor, record and translate, at a unit level, the overall effect of the temperature history of a food product (Vaikousi et al., 2008) on its quality and safety. The basic requirement for an effective TTI is to indicate a clear, continuous and irreversible reaction to changes in temperature. Commercially available TTIs include a number of diffusion, enzymatic, polymer based, solid state reaction and microbiological systems. Diffusion-based TTIs such as the Monitor Mark ® TTI, commercialized by the 3 M Company are based on the temperature-dependent diffusion reaction of a colored fatty acid ester along a porous wick made of high-quality blotting paper. Its measurable response is the distance of the advancing diffusion front from the origin (Kerry et al., 2006). Enzymatic systems such as the VITSAB Check Point ® TTI are based on a color change in the TTI induced by a pH drop resulting from the controlled enzymatic hydrolysis of a lipid substrate which changes the color of the chromatic indicator from green over yellow to orange red (Kerry et al., 2006; Tsironi et al., 2008). Polymer-based systems such as the Fresh Check ® TTI produced by the company TempTime, are based on the solid state polymerization of a thinly coated colorless acetylenic monomer that changes to a highly colored opaque polymer at a temperature-dependent rate (Nuin et al., 2008). Solid state reaction systems represented by the OnVu™ TTI produced by the Ciba company are based on photosensitive compounds such as benzylpyridines. Once exposed to a low wavelength light, they become colored and this colored state reverses to the initial colorless state according to temperature (Tsironi et al., 2008). Microbiological TTIs are proposed by the French company CRYOLOG. TRACEO ® and (eO) ® are microbiological TTIs made of selected strains of lactic acid bacteria. Prior to utilization, these TTIs are stored in a frozen state (−18 °C) to prevent International Journal of Food Microbiology 138 (2010) 119–129 ⁎ Corresponding author. Ecole Nationale Vétérinaire d'Alfort, Unité MASQ, Pôle HQSA, 7, Avenue du Général de Gaulle 94704 Maisons Alfort, France. Tel.: + 33 1 43 96 71 78; fax: +33 1 43 96 70 90. E-mail address: mellouze@vet-alfort.fr (M. Ellouze). 0168-1605/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2009.12.012 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro