For an Eco-designed cold chain – optimizing energy consumption, safety, quality and shelf-life of refrigerated processed foods – OPTICOLD

The project will build a global model of the cold chain, by linking energy consumption with variables that determine food shelf life: its microbiological safety and its quality. This type of model does not exist at the moment for the whole cold chain. It will be established using the relations linking all these variables, energy consumption, safety and quality, to the temperatures of the cold chain. In particular cold in the food processing plant, for which scientific knowledge is lacking, but for which empirical professional knowledge indicates a high potential to save energy, will be
studied in priority.

The global model of the cold chain, that integrates temperatures distribution at all the refrigerated steps of processing, the energy needed to obtain these temperatures and the impact of these temperature on food quality, have been built. The model was used to simulate scenarios, and to calculate for instance the impact on food quality and on energy cost, of modifications in the cold temperature at the various steps of the process.
A multicriteria approach was developed, so far using data from the literature, to optimise choices between energy cost, food quality and food safety. It will be applied to data produced and scenarios simulated in the OPTICOLD project.
Impact of temperature on food spoilage for the three products of the has been acquired. This information is being used in the global model. In the case of fresh cut salads, the release of water from the vacuole of a category of cells is a likely cause of spoilage and could represent an early marker of quality loss and decrease in processability of the raw material.
Strains diversity of L. monocytogenes was characterised for cold adaptation and markers of a rapid adaptation have been identified. The consequences of this diversity on the risk of listeriosis have been quantitatively assessed. A gene coding for an RNA helicase and a gene involved in the division process have been identified as markers of the exit of lag phase in B. cereus. L. monocytogenes cells exposed to stresses seems to have a reduced growth probability at cold temperatures. Growth probability of individual spores of B. cereus in food matrices is being measured. These data will be used to better adjust the multicriteria optimisation.

A management of cold chain based in priority on energy consumption will permit to reduce energy consumption, but it may results in cold temperatures distribution more prone to deteriorate quality and safety (the variables determining shelf life), and consequently leading to an increase in food wastes. In the next steps of the OPTICOLD project, the global model will be used to simulate various scenarios for the different food products, with different energy costs, food safety risks and wastes. The multicriteria approach developed in the project will then be applied to the scenarios. The food companies and various stake-holders will be asked to define their weight for the different choice criteria, so as to include various priorities.
Project results on food spoilage and pathogenic bacteria will improve the quantification of the impact of cold and should permit to adjust more finely the compromise between energy cost, food safety and food waste.
Further to OPTICOLD, it would be interesting to explore the way toward exploiting the project results into easy to use tools available for stakeholders. This would particularly concern the global model and the muticriteria approach, as well as the markers of spoilage and of microbial risk.

Guillier L., Duret S., Hoang H.M., Flick D., Nguyen-The C., Laguerre O. (2016) Linking food waste prevention, energy consumption and microbial food safety: the next challenge of food policy? Current Opinion in Food Science, 12:30–35.
Fritsch, L., Guillier, L., Augustin, J.-C., (2018). Next generation quantitative microbiological risk assessment: Refinement of the cold smoked salmon-related listeriosis risk model by integrating genomic data. Microbial Risk Analysis 10, 20-27. doi.org/10.1016/j.mran.2018.06.003.
Duret, S., Hoang, H., Derens-Bertheau, E., Delahaye, A., Laguerre, O. and Guillier, L. (2018), Combining Quantitative Risk Assessment of Human Health, Food Waste, and Energy Consumption: The Next Step in the Development of the Food Cold Chain? Risk Analysis, 39(4)906-925. doi: 10.1111/risa.13199.
Fritsch, L., Felten, A., Palma, F., Mariet, J.-F., Radomski, N., Mistou, M.-Y., Augustin, J.-C., Guillier, L., (2019). Insights from genome-wide approaches to identify variants associated to phenotypes at pan-genome scale: Application to L. monocytogenes' ability to grow in cold conditions. International Journal of Food Microbiology 291, 181-188. doi.org/10.1016/j.ijfoodmicro.2018.11.028.
Français M, Carlin F, Broussolle V, Nguyen-Thé C. 2019. Bacillus cereus cshA is expressed during the lag phase of growth and serves as a potential marker of early adaptation to low temperature and pH. Appl Environ Microbiol 85:e00486-19. doi.org/10.1128/AEM.00486-19.
Sorin, C., Mariette, F., Musse, M. 2019. NMR study of fresh cut salads: influence of temperature and storage time on leaf structure and water distribution in escarole. Magnetic Resonance in Chemistry, Accepted article. doi: 10.1002/mrc.4865.

The cold chain permits to process and commercialise in good conditions of quality and safety a wide range of foods. However the cold chain represents high energy consumption. OPTICOLD objective is to increase sustainability of the cold chain by optimising the compromise between energy consumption, safety, quality and shelf life for refrigerated processed foods. Cold chain is currently managed to respect target temperatures, determined by regulation and specifications agreed among stake-holders. OPTICOLD project proposes a new approach, aiming at a multi-criteria management of the cold chain, with a main role for minimisation of energy consumption.
To meet this objective, OPTICOLD project will build a global model of the cold chain, by linking energy consumption with variables that determine food shelf life: its microbiological safety and its quality. This type of model does not exist at the moment for the whole cold chain. It will be established using the relations linking all these variables, energy consumption, safety and quality, to the temperatures of the cold chain. In particular cold in the food processing plant, for which scientific knowledge is lacking, but for which empirical professional knowledge indicates a high potential to save energy, will be studied in priority.
A management of cold chain based in priority on energy consumption will permit to reduce energy consumption, but it may results in cold temperatures distribution more prone to deteriorate quality and safety (the variables determining shelf life). It is therefore necessary to develop multicriteria approaches to determine the margins of action on temperature distributions, or “acceptable variations for cold temperatures”, considering the requirements for quality and safety. This implies the most accurate prediction of safety and quality as a function of cold temperatures. A the moment, relations between food safety or quality and cold temperatures are described with important uncertainties, which imply important margins of safety on the temperature regimes of the cold chain, and therefore over-spending of energy. OPTICOLD will therefore integrate to the studies on energy consumption, researches on the physiology of cold adaptation in bacteria and researches in bio-physic on plant tissues destructuration, as the cause of non-microbiological spoilage of raw plant foods.
In an optimised cold chain, the relation built in the project between energy cost and the shelf-life variables will permit to quantify the gain in energy consumption reduction with the consecutive loss in shelf-life, for all the steps of the chain. Then the steps for which the most important gain in energy consumption can be obtained for the least loss in shelf life will be identified.
The approach of the OPTICOLD project will be developed on processed, refrigerated foods. Three food categories will be studies, to cover very different conditions to impart a generic dimension to the project: living food with a physiological activity which spoilage is mostly not microbiological (fresh cut salads), dead and raw food (fresh pastry dough), pasteurized chilled food (fresh pasteurized pasta). The possibilities to generalize the OPTICOLD approach developed on these three food categories to other types of foods will be studied.