The present invention relates to the food industry and in particular to the milk industry but more generally the invention is targeted at liquids which will be fermented, in particular by lactic acid bacteria. This is the case with milk, to which bacteria are added in order to produce yoghurt, cheese, and the like, but this can also be the case with soya milk, for example.
The advantage of maintaining, in the milk used to make yoghurts, an amount of dissolved O2 which is low, as low as possible, with the aim of lowering the latency time of the lactic acid bacteria and thus of shortening the production time, has been reported in the literature of this technical field.
It is appropriate to recall in what follows the concepts which are involved here.
Lactic acid fermentation is the process by which lactic acid bacteria grow, under anaerobic conditions, producing lactic acid from the carbohydrates present in the product which is fermented (lactose in the case of milk).
Lactic acid bacteria, which include, for example, lactobacilli, streptococci, bifidobacteria, leuconostocci and enterococci, are anaerobic bacteria, partially tolerant to oxygen.
The growth curve of the bacteria during lactic acid fermentation is the same as for any other fermentation and comprises:
A lever for improving the productivity of lactic acid fermentation is to reduce the lag phase. In particular, it has been proven that a low level of dissolved oxygen in milk at the start of fermentation makes it possible to reduce the duration of the lag phase. This is because the oxygen dissolved in milk would delay the production of lactic acid.
The literature in this field has in particular shown the following points:
However, vacuum degassing exhibits the following disadvantages:
While the preceding example describes an in-line injection, copious literature furthermore proposes to carry out a deoxygenation in “batch” mode, but “batch” deoxygenation, in addition to exhibiting the same disadvantages as in-line deoxygenation, represents an amount of gas consumed per amount of liquid treated which is high. Furthermore, “batch” deaeration, that is to say the injection of a neutral gas by diffusion or agitation of the liquid, requires in this case one more step in the process, a step which will consume time, knowing that the objective is to save time on the latency step at the start of the fermentation. In conclusion, to add a “batch” deoxygenation step will in all probability have the opposite effect to that expected on the productivity.
Furthermore, it is not always possible to ensure permanent agitation or bubbling of the liquid. This is because the milk is often fermented for the production of yoghurt or cheese, and the fermentation step makes possible the formation of a gel, the texture of which is important for the quality of the final product. If agitation or bubbling disturbs the formation of the gel, the product obtained will not have the desired texture.
On the other hand, the injection of a gas into milk is limited by the formation of foam which causes processing difficulties as well as cleaning difficulties, and product losses. Finally, foaming can detrimentally affect the state of the milk proteins.
One of the objectives of the present invention is therefore to provide a new fermentation process exhibiting better productivity than a conventional process because it employs a fermentation medium having a level of dissolved oxygen which is zero or virtually zero, without the need for a step of deoxygenation with vacuum or with nitrogen as according to the prior art.
As will be seen in more detail in what follows, the present invention proposes to work under the following conditions, where the liquid, for example milk, but the targeted “liquid” can also be a mixture, for example a mixture for the production of a yoghurt, undergoes in particular the following steps:
According to one of the embodiments of the invention, a small amount of CO2 (or a gas comprising CO2), for example an amount of between 20 and 1500 mg/l, preferentially an amount of between 150 and 900 mg/l, can be injected into (dissolved in) the liquid: in line (before its arrival in the tank) or in an upstream vessel, in order to prelower the pH thereof and to thus further reduce the fermentation time. This is because fermenting a liquid amounts to lowering its pH by the action of bacteria, which produce lactic acid. Thus, for example, during the fermentation of milk for the production of yoghurt, the pH falls with the growth of lactic acid bacteria; when the pH reaches 4.6 (isoelectric pH of caseins, major proteins of milk), the milk curdles, forming a gel. If CO2 is added, the pH falls a little faster, supporting the work of the bacteria.
This small amount of dissolved CO2 will also have the advantage of more effectively protecting the milk from a possible uptake of oxygen via air during transfers into partially inerted containers.
In the case of certain liquids to be fermented (for example yoghurts), which are not “simple” milk, liquids which result from the mixing of several liquid and possibly solid ingredients, for example considering the case of a yoghurt, the liquid which will be fermented, and which will thus pass through the pasteurizer before inoculation, is a mixture of milk, milk protein powder, optionally sugar, optionally cream, and the like. It is then very advantageous, in the context of the present invention, for the mixing of these ingredients to be carried out under inerting in order, on the one hand, to remove the dissolved oxygen present in the ingredients and, on the other hand, to avoid the incorporation of oxygen due to the very action of mixing.
The main advantages of the technical proposal according to the present invention can be summarized thus:
Unlike the prior art touched on above in the present description, the present invention takes advantage of the fact that the residual oxygen in the liquid, for example milk, on leaving pasteurization is very low and that the tank is inerted BEFORE the arrival of the liquid. Thus, according to the present invention, deoxygenation is not carried out, uptake of oxygen is avoided, which consumes less gas, and that, by the fact that the inerting takes place in parallel with the pasteurization, a time for an additional step is not added.
The appended
The following plant elements can be recognized in the FIGURE:
The present invention consequently relates to a process for the production of a fermented liquid food, comprising the following steps:
characterized in that the tank was, before the arrival of the liquid, inerted beforehand, for example by flushing the headspace of the tank using a neutral gas, such as nitrogen, containing or not containing CO2.
An inerting by flushing using a gas is touched on above but other methods can be envisaged, and in particular the use of the low pressure created during the aseptic cleaning of the tank and the injection of an inert gas, such as nitrogen, to compensate for the low pressure.
While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing i.e. anything else may be additionally included and remain within the scope of “comprising.” “Comprising” is defined herein as necessarily encompassing the more limited transitional terms “consisting essentially of” and “consisting of”; “comprising” may therefore be replaced by “consisting essentially of” or “consisting of” and remain within the expressly defined scope of “comprising”.
“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.
All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.
Number | Date | Country | Kind |
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FR 1857436 | Aug 2018 | FR | national |
This application is a § 371 of International PCT Application PCT/EP2019/071390, filed Aug. 9, 2019, which claims § 119(a) foreign priority to French patent application FR 1857436, filed Aug. 10, 2018.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/071390 | 8/9/2019 | WO | 00 |