MILK DECONTAMINATION PROCESS BY DEOXYGENATION AND CONTROL OF DISSOLVED GASES

Abstract

A process for treating a food medium, and in particular milk or a dairy medium, comprising a deoxygenation operation of the medium by the injection of selected gases or gas mixtures, characterized in that the medium into which the injection is carried out is at a temperature in the range of 30°C-70°C, preferably 40-60°C, and even more preferably in the range of 50-60°C. Figure from the abstract: Fig. 1

Description

Description Title of the invention: METHOD FOR DECONTAMINATING THE MILK BY DEOXYGENATION AND GAS CONTROL DISSOLVED

[0001] — The present invention relates to the field of food, and it is more concerned with particularly in the dairy sector, with the milk itself but also the by- products of its microfiltration or ultrafiltration, i.e. concentrates and retentates milk, but also whey, possibly demineralized, possibly skimmed, possibly lactose-free, as well as the by-products of its micro or ultrafiltration i.e. serum permeates and concentrates.

[0002] But of course the invention also relates to other food liquids, such as for example, the liquids involved in protein extraction plant-based.

[0003] Currently, in common industrial practice, milks, whether liquid, Skimmed, concentrated or dried in powder form, undergo in the majority of In this case, before concentration { which is a filtration step to concentrate a molecules, such as proteins for example), a "preheating", carried out at temp- elevated temperature (typically from 60°C to 95°C) for a specified period of time, or another pasteurization, in order to ensure sufficient destruction of the flora microbial.

[0004] — Although this heat treatment is quite severe, it leads to a final product of which The bacteriological quality is not optimal, for the following reasons:

[0005] - this is a pasteurization process which aims to remove part of the load, But this is not sterilization, so some bacterial load remains which, when the temperature increases (for example, during filtration), can develop again. On the other hand, there are bacteria that are more resistant to heat. Furthermore, this technique has some drawbacks, the most significant of which is... The impactful factor is that it leads to the denaturation of milk proteins. This denaturation- Turation has an impact on the nutritional value of the product and risks leading to the technical downgrading of the finished product (milk, milk powder, etc.), This can lead to a loss of commercial value or even outright exit from the circuit. sale.

[0006] — Furthermore, the tendency among many milk users is to prefer products having undergone only moderate or low heating (for example, the powders designated in Anglo-Saxon terminology uses the names "medium-heat" or "low-heat", on These products are called "thermized" in France. These powders are defined by a soluble protein content measured under standardized conditions (ADMI. 1965). "Low-heat" powders must contain more than 6 mg / g of nitrogen from soluble proteins, while "medium-heat" powders must contain between 1.5 and 6 mg / g. Understandably, it would therefore be very interesting to be able to lower preheating or pasteurization temperatures compared to the conditions currently practiced, while focusing on finding other ways to control the number of bacteria surviving in milk. It should be noted that currently, milk decontamination methods rely on pasteurization, UV treatment, or the use of pulsed light. As mentioned previously, pasteurization has the major drawback of impacting the organoleptic quality of the product. UV treatment and pulsed light preserve the intrinsic qualities of milk; however, the high investment costs are prohibitive. Furthermore, these last two technologies are still in the experimental phase and have not yet been adopted by the industry. As will be seen in more detail below, the present invention proposes a method of deoxygenating milk allowing control of dissolved gases, through the use of well-selected gases or mixtures. According to the invention, the use of inert gases such as nitrogen or argon is preferred, possibly mixed with an active gas such as carbon dioxide, nitrous oxide, or hydrogen (for its redox properties). This deoxygenation can be carried out from milking to final packaging, including intermediate storage, processing, and transport stages, taking every precaution to prevent any subsequent oxygen uptake. The main benefit of deoxygenation is to limit or eliminate thermal processes (especially treatment at excessively high temperatures), thus preserving milk proteins and the organoleptic aspects of the final product. But in addition to the use of selected gases or gas mixtures, the present invention, unlike the prior art, proposes to carry out such gaseous treatment of milk not at cold, but within a given temperature range. The experiments carried out by the Applicant [have indeed suggested that when the optimum growth temperature of a bacterium is exceeded, it is put in difficulty, in a state of stress, so to speak. It even seems that there is a synergy between this stress ("thermal") and the stress created by the absence of oxygen, and therefore a tenfold effect that is not limited to slowing microbial growth since in some trials, microbial mortality was even observed. It is therefore recommended according to the invention to operate at a milk temperature in the range of 30°C-70°C, preferably 40-60°C, and even more preferably in the range of 50-60°C. To better understand the present technical proposal, let us consider below an example of implementation, detailed in connection with [fig.1] below. To simulate a microfiltration process, 60 litres of dairy retentate were used, stored in a tank (reference 1 in [fig.1]), and a "control" test was carried out on the one hand and a "deoxygenation" test on the other. "Control" test: The dairy medium was heated to 50°C, for example by a double jacket of the tank in which hot water circulates. This liquid was circulated in a closed loop (see figure 1 and in particular the pump 3) for 5 hours while maintaining the target temperature. We perform a sample taken once per hour for the 5 hours during which the The middle loops. "Deoxygenation" test: This trial was conducted as follows using the same batch of retests: Deoxygenation of the liquid by in-line injection (point 2 in the figure) of a mixture 30%COy / 70%N;, . Here, a direct injection was carried out into the ca- nalisation, but we can of course consider other methods, and in particular use a Venturi type injector, or a static mixer. Once the dissolved oxygen is removed (the dissolved oxygen passes into the bubbles) nitrogen (Henry's law) and once back in the tank, the nitrogen bubbles oxygen-rich particles exit the liquid and go into the headspace, then to the outside of the tank, taking with them the oxygen they contain), the The liquid was heated to 50°C by a double jacket integrated into the tank. storage. Once the set temperature is reached, the 5 hours of operation were deducted, in other words, as before, a deduction was made once an hour for the 5 hours during which the fluid circulates loop (the difference for this test being that we waited for the oxygen dissolved (either removed to start heating). The results obtained during these tests are presented in the table below (where CFU / mg = "Colony Forming Unit"). It is important to note first that, given the duration of a trial, the two trials could not be carried out on the same day. The "Control" trial was conducted on the first day, which explains why the "Deoxygenation" trial has a much higher concentration of microorganisms, as they had more time to develop. The results observed on the "Deoxygenation" test are therefore all the more significant and interesting, and clearly highlight the value of the process according to the invention. The microbial load in the "Control" remained stable for 2 hours. In contrast, in the "Deoxygenation" trial, it decreased drastically during the deoxygenation and heating phase, dropping by 1.3 log units very rapidly. This microbial mortality continued during the first hour of operation. Thus, overall, deoxygenation combined with moderate heating reduced the total bacterial count in the milk by 2.5 log units in 1 hour of recirculation. In the control case, a slight decrease in total flora began to be observed after 3 hours. This is most likely due to the fact that, as the system operates in a closed loop, the bacteria gradually consumed oxygen and thus deoxygenated it very progressively. This would not be the case if the system were supplied with "fresh" liquid, as in a conventional dairy process. [Table 1] Control Deoxygenation Cold Retentate (TO of Control) |>30000 640000 TO deoxygenated retentate at 32000 50°C 1h >30000 2800 T2h >30000 2100 [Tan 9800 1700 [Tan 6700 2100 |T 5h 8500 [1200 Although [fig.1] suggests an in-line injection, it is clear that an injection into a tank is also possible. The present invention relates to a method for treating a food medium, and in particular milk or a dairy medium, comprising an operation of deoxygenating the medium by the injection of selected gases or gas mixtures, characterized in that the medium in which the injection is carried out is at a temperature in the range of 30°C-70°C, preferably 40-60°C, and even more preferably in the range of 50-60°C.

Claims

[Claim 1] Demands Milk treatment process, comprising a deoxygenation operation by the injection of selected gases or gas mixtures, characterized in that the water in which the injection is carried out is at a temperature in the range of 50-60°C.

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