2024-03-08 10:30:36
Scientists have developed three simulation tools to assess the feasibility of raising the ambient temperature in processing workshops in the food industry, while ensuring the health quality of the products. In initial tests, a 30% reduction in energy consumption was calculated.
In meat processing workshops, the regulations of the European hygiene package require that the core temperature of meat products does not exceed 7 degrees. To guarantee the health quality of their products, food manufacturers tend to cool their workshops significantly, often to a temperature between 4 and 5 degrees. This practice causes high energy consumption as well as a deterioration of working conditions for employees. Scientific teams from the Carnot AgriFood Transition Institute[1] carried out a project called Coolcontrol whose objective is to develop a methodology to assess the feasibility of raising the ambient temperature in processing workshops, while ensuring the health and organoleptic quality of the products.
“Our study was carried out on foodstuffs of meat origin, and more particularly on pork, because it is a material on which certain microorganisms will develop more easily and to a greater extent, explains Florian Brisson, R&D engineer at Pôle Cristal. We have deliberately selected this meat, which is a little more risky, in order to work in the most unfavorable context possible. We developed three simulation models, then compared their results to sausage preparation tests carried out in real conditions. »
The first two tools are both interconnected and linked to the food matrix. The first is a thermal model, the role of which is to predict the increase in product temperature as the transformation process progresses. It takes into account different parameters such as the nature of the product, like pork, which has a particular conductivity and thermal capacity. Other parameters are also integrated such as the outside temperature, convective effects, that is to say the presence or absence of air currents coming for example from fans, as well as the manufacturing process. In the case of studies, the pork meat underwent a curettage step with blades mixing the sausage meat, a process which contributes to a significant contribution of heat to the meat material.
A second model, this time microbiological, was developed and predicts the growth of microorganisms as a function of the temperature of the food matrix estimated by the thermal model. In the case of studies, three types of germs, the most dangerous on sausage meat, were measured: Escherichia coli, Listeria monocytogenes and Bacillus weihenstephanensis.
The results of the three models compared to sausage manufacturing trials
In parallel with these two simulation tools, an energy model was built, the role of which is to predict the energy consumption necessary to maintain the desired temperature in the meat processing workshop. It works based on variables such as the set temperature, the external contributions linked to the transfer of heat due to the external temperature, as well as the internal contributions linked to the heat released by the people present in the workshop, but also that coming from machines operating in the processing enclosure.
To validate these three simulation models, their results were compared to a series of experiments carried out in the laboratory and consisting of preparing sausages in conditions as close as possible to industrial reality. Results: the thermal model proved capable of predicting the evolution of the temperature in the food matrix with a degree of precision very close to reality. “We changed the ambient temperature during our tests from 6 to 11 degrees and our model estimated the temperature of the food product with a margin of error less than or equal to one degree, which is entirely acceptable”, analyzes Frédéric Bazantay, director of the Pôle Cristal. As for the microbiological analysis model: “the estimates are consistent with the experimental results. Faced with an increase of 5 degrees in the ambient temperature, we observe almost no difference in the evolution of the population of microorganisms in the product for 5, 10, and even 20 days after the sausage manufacturing process. . »
In terms of pathogenic flora, the only point to be vigilant is surface contamination. “Experiments show that as soon as there is a little meat material remaining on the work surfaces and the various tools, the increase in microorganisms is much greater on these surfaces with an ambient temperature of 11 degrees compared to 6 degrees, analyse Florian Brisson. But this risk can be controlled in different ways, including by carrying out more extensive cleaning. »
Providing a decision support tool to manufacturers in the agri-food sector
As much as the results of the first two models are consistent with the experiments, those of the energy model turned out to be different. The latter estimated an energy saving of around 30% by going from an ambient temperature of 6 to 11 degrees, while the experiments tended towards a gain of 75%. “We believe that the refrigeration machine used during the tests malfunctioned, because we have calculated theoretically what is the maximum gain that can be expected by raising the set temperature by 5 degrees and this gain cannot exceed 50%. “, adds Frédéric Bazantay.
In any case, the Coolcontrol project made it possible to demonstrate the concept of three tools capable of measuring the energy benefit of raising the ambient temperature in processing workshops, while measuring the risk that such a change may have on the health quality of food products. The scientists will continue this research work by improving the predictive nature of the three models, particularly the energy model, and by testing it on several types of food products and on different transformation processes. They are also in discussions with manufacturers to carry out experiments in real conditions in the food industry.
“Even if we obtain a gain in energy consumption of 30%, this is a very good result, easy to obtain, with zero investment, provided of course that good health control of the foodstuffsrejoices Frédéric Bazantay. We have here a lever for energy efficiency in the processing workshops and many industrialists have shown signs of interest in our project. Ultimately, our ambition is to offer them a decision-making tool that can be applied to meat processing workshops, but also to other types of agri-food industries, such as out-of-home catering. »
[1] The CoolControl project was carried out by ADRIA, Pôle Cristal and the Lubem laboratory, all three members of the Carnot AgriFood Transition institute
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