Process and installation for the production of insect larvae

Abstract

The present invention relates to a method for producing insect larvae comprising a rearing step (1) of the larvae in a container holding a mixture of larvae and their rearing medium, followed by a separation step (3) of the larvae and their rearing medium, characterized in that the method comprises a drying step (2) of the mixture of larvae and their rearing medium between the end of said rearing step and said separation step. The invention also relates to an installation for carrying out this method.

Description

Title of the invention: Method and installation for producing insect larvae Field of invention

[0001] The present invention relates to the general field of the breeding of insect larvae, in particular black soldier fly larvae, and in particular to the separation of mature larvae from their breeding environment.

[0002] Insect larvae, and in particular black soldier flies, are reared in containers containing substrate, for example agricultural co-products or organic waste. This substrate constitutes the breeding medium for the larvae and is the food source for the larvae. As the larvae are reared, this substrate is consumed by the larvae and the breeding medium in which the larvae evolve is transformed into frass (a mixture of uneaten substrate, larval molts and larval excrement).

[0003] The substrate, the food source of the larvae, must be very moist with a water content of between 60% and 90% so that the larvae can ingest the substance.

[0004] Insect larvae, and in particular black soldier flies, are reared on an industrial scale to be subsequently used as protein for animal or human food and in the form of oil. Frass, which is an effective fertilizer, is also used.

[0005] For this it is necessary to use a separation step to separate the mature larvae from their breeding medium consisting of frass. After this separation step, the larval and frass flows are separated and can be used independently. This separation step is therefore a key step in the overall insect breeding process.

[0006] This separation is generally carried out on a vibrating screen sieve, for example with a solution described in the document “Case studies -> Separation of black soldier flies” https: / / www.russellfinex.com / fr / etudes-de-cas / separateur-automatique-pour-larves-de-bsf / State of the art

[0007] Patent EP3171693B1 is known in the state of the art, describing a continuous system for rearing dipterous insects, comprising a bioconversion unit comprising a plurality of separate larval compartments all adapted to contain insect larvae and growth media and a mechanism for sequentially feeding growth media.

[0008] This patent specifies that the larvae and larval excrement (dried digestate and other materials) can be separated, for example using a zig-zag air separator and / or a sieve. The larvae and excrement can then be processed separately. For example, the excrement can be dried and heat-treated, the larvae can be washed, cooked, dried, cooled or degreased.

[0009] Patent FR3081679 concerns the spawning environment, and mentions the separation of frass / larvae. It provides that the nutrient substrate has a humidity of between 3 and 15%, and proposes the use of an oscillating nutation sieve (“tumbler screening machine”, Allgaier) or a linear vibratory sieve (“linear screening machine”, Mogensen).

[0010] Patent application WO2021255379Al relates to a method for sorting insects comprising the successive steps of: • supply of a mixture comprising nymphs, and • sieving allowing separation of the nymphs from the rest of the mixture, said sieving step comprising sieving the mixture with a plastic screen sieve.

[0011] The sieving of the mixture with a plastic screen sieve may in particular be sieving with a polyurethane screen sieve.

[0012] The sieving of the mixture with a plastic screen sieve can be carried out with a screen sieve inclined relative to a horizontal plane. The sieving of the mixture with a plastic screen sieve can involve movement in a circle or oval in its plane of extension, without a component orthogonal to the plane of the sieve to improve the quality of the sorting and limit the shocks suffered by the nymphs. Disadvantages of the prior art

[0013] The solutions of the prior art are not entirely satisfactory because the optimal conditions for breeding do not correspond to those which are optimal for the separation by sieving of the larvae and their breeding environment.

[0014] Indeed, for good feeding of the larvae and good growth, it is necessary for the substrate to be relatively moist. Conversely, for good sieving, the breeding medium in which the larvae are found at the end of their growth must be relatively dry to allow effective separation without causing blockage or clogging of the sieve.

[0015] The solutions of the prior art provide a compromise between the conditions, in particular humidity and temperature, of the breeding medium containing the larvae to allow suitable sieving without unduly affecting the growth rate. However, in order to avoid excessively long growth times, it is necessary to increase the humidity level of the initial substrate, which leads to poor separation due to clogging of the sieve and sticking of the breeding medium to the larvae, and therefore an imperfect separation requiring post-treatment. Solution provided by the invention

[0016] In order to overcome these drawbacks, the present invention relates to a method for producing insect larvae comprising a step of rearing the larvae in a container containing a mixture of larvae and their rearing medium followed by a step of separating the larvae and their rearing medium, characterized in that the method comprises a step of drying the mixture of larvae and their rearing medium between the end of said rearing step and said separation step.

[0017] Preferably, said separation step is a granulometric and / or densimetric separation.

[0018] Advantageously, said drying step reduces the humidity level of the larvae breeding environment by at least 10 points.

[0019] According to a variant, said drying step is carried out at a temperature of the mixture of larvae and their breeding medium 5°C to 25°C higher than the breeding temperature.

[0020] According to a preferred embodiment: • said breeding step (1) is carried out in a container containing a mixture of larvae and their breeding medium; • in that said breeding step (1) is followed by a step (3) of separating the larvae and their breeding medium by sieving; • and in that the method comprises a drying step (2) for reducing the humidity of the larvae breeding medium between the end of the breeding step and said separation step.

[0021] According to a particular variant, said drying step is controlled by at least one humidity sensor measuring the humidity level of the larvae breeding environment.

[0022] Preferably, the duration of said drying step is a function of a set value for the humidity of the larvae rearing medium, the age of the larvae and the humidity measured by said humidity sensor.

[0023] According to a preferred embodiment, said drying step is carried out by a belt dryer.

[0024] According to another embodiment, said drying step is carried out by a fluidized bed dryer.

[0025] The invention also relates to an installation for producing insect larvae comprising a larvae rearing area and equipment for separating the larvae and their rearing environment, characterized in that it further comprises a dryer arranged between said larvae rearing area and said separation equipment.

[0026] Advantageously, said dryer ensures a reduction in the humidity level of the larvae breeding environment of at least 10 points.

[0027] Detailed description of a non-limiting example of embodiment

[0028] The present invention will be better understood on reading the following description, concerning a non-limiting example of embodiment illustrated by the appended drawings where: • [Fig.l] [Fig.l] represents a schematic view of the process which is the subject of the invention; • [Fig.2] [Fig.2] represents a schematic view of the breeding facility. General principle

[0029] The method according to the invention is distinguished from the prior art by a breeding step (1) in conditions optimized for the feeding and growth of the larvae in a period of time reduced to the period of weight gain of the larvae or increase in the protein level of the larvae, and not extending beyond this period to prevent the larvae from exceeding their peak mass to enter a fasting phase.

[0030] Under the rearing conditions and with the substrate used, it was observed, from juvenile larvae, that when the larvae reach their peak mass, their rearing medium is too humid to be effectively sieved using standard sieving techniques. Usually, the larvae were kept for an additional 3 to 5 days in the rearing area to allow time for the mixture of larvae and their rearing medium to dry and reach the target humidity level.

[0031] The invention proposes to solve this problem by adding a step of drying the mixture of larvae and their breeding medium before the separation step.

[0032] During these additional 3 to 5 days, the larvae could enter a fasting phase leading to a loss of mass and / or protein levels.

[0033] These 3 to 5 days also involved considerable productivity losses due to the occupation of space in the breeding area.

[0034] In order to overcome the constraint of drying the mixture consisting of the larvae and their breeding environment in the breeding area, the installation of a dedicated dryer before the sieving step makes it possible to sieve the mixture consisting of the larvae and their breeding environment as soon as the larvae have spent the necessary time in the breeding area to reach their maximum weight.

[0035] The drying step (2) must be sized to reduce the humidity by at least 10 points in order to improve the operating conditions of the screening equipment without extending the time spent in the breeding area, and therefore eliminating the fasting phase.

[0036] The drying temperature is slightly higher than the optimum temperature for rearing the larvae in their rearing environment (the difference is less than 25°C and preferably of the order of 15 to 25°C) so that the additional drying step does not harm the integrity of the larvae.

[0037] The advantages resulting from the proposed method are multiple: • gain in yield from the breeding stage (in kg of fresh larvae) of at least 20% in: • increasing the mass of larvae collected; • significantly reducing non-conformities, as non-conforming batches are mostly batches with a long cycle time; • gain in breeding capacity in the breeding area due to the reduction in the time spent by the larvae in this area; • adaptation of the flow of material to be treated during the separation stage (3) to the optimal operating conditions of a sieve. Drying conditions

[0038] This drying step is carried out at a temperature slightly higher than the breeding temperature, on a layer a few centimeters thick of mixture consisting of the larvae and their breeding environment in order to minimize the discomfort of the larvae which thus remain in their breeding environment during the drying step.

[0039] To minimize handling and stress on the mixture in order to avoid damaging the larvae, drying is preferably carried out on a woven belt dryer. A thickness of a few centimeters of mixture consisting of larvae and their rearing medium is distributed uniformly on a woven belt through which air can pass while retaining the mixture to be dried in order to prevent it from being carried away by the air flow. The belt advances at a defined speed to evaporate part of the moisture in the larvae rearing medium and to reach at the end of the dryer a residual humidity at least 10 points lower than the initial humidity, and to convey the mixture from the inlet to the outlet of the dryer. Heated air is drawn through the mixture and through the belt in order to dry the larvae rearing medium. The airflow can be directed either from top to bottom or from bottom to top.

[0040] A humidity sensor at the outlet of the belt makes it possible to adjust the residence time of the mixture and the thermal power used in order to adjust the humidity level of the larvae rearing medium at the outlet. This humidity level of the larvae rearing medium is the key parameter for obtaining efficient screening downstream.

[0041] Alternatively, the dryer used may also be a fluidized bed dryer.

[0042] This drying stage taking place at the end of the larval breeding period, the breeding environment in which the larvae evolve is frass. Cultivation and separation facility

[0043] The larvae are reared in a rearing area (10) in which the atmosphere is controlled in temperature and humidity to promote consumption by the larvae. of the substrate. In this rearing area (10), the larvae evolve in their rearing environment in multi-stage modules. A control area (11) is provided to check the maturity of the larvae and detect any dead larvae. In the event of mortality or non-compliance, the multi-stage module is transferred to a waste area (12). The other multi-stage modules are transferred to a turner (20) which allows the mixture of larvae and their rearing environment to be poured into a dryer (21) receiving a heat input. Typically, the dryer is a belt dryer or a fluidized bed dryer and the heat input is provided by circulating hot air to reduce the humidity level of the larvae rearing environment by at least 10 points between the inlet of the belt dryer (21) and its outlet.

[0044] After the drying step, the separation is carried out by a sieve (22), for example a trampoline sieve.

[0045] The frass is transferred to a granulation line (23); and the larvae are conveyed to a processing line (30) producing a protein meal and oil.

Claims

Claims

1. A method of producing insect larvae comprising a step of rearing (1) the larvae in a container containing a mixture of larvae and their rearing medium followed by a step (3) of separating the larvae and their rearing medium, characterized in that the method comprises a step of drying (2) the mixture of larvae and their rearing medium between the end of said rearing step and said separation step.

2. Process for producing insect larvae according to claim 1 characterized in that said separation step is a granulometric and / or densimetric separation.

3. Method for producing insect larvae according to claim 1 characterized in that said drying step reduces the humidity level of the larvae rearing medium by at least 10 points.

4. Method for producing insect larvae according to claim 1 characterized in that said drying step (2) is carried out at a temperature of the mixture of larvae and their breeding medium 5°C to 25°C higher than the breeding temperature.

5. A method for producing insect larvae according to claim 1 comprising a breeding step (1) characterized in that: • said breeding step (1) is carried out in a container containing a mixture of larvae and their breeding medium; • in that said breeding step (1) is followed by a step (3) of separating the larvae and their breeding medium by sieving; • and in that the method comprises a drying step (2) for reducing the humidity of the breeding medium of the larvae between the end of the breeding step and said separation step.

6. Method for producing insect larvae according to claim 1, characterized in that said drying step (2) is controlled by at least one humidity sensor measuring the humidity level of the larvae breeding environment.

7. Method for producing insect larvae according to the preceding claim, characterized in that the duration of said drying step (2) is a function of a set value for the humidity of the medium.

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13. larval rearing, larval age and humidity measured by said humidity sensor. Method for producing insect larvae according to claim 1, characterized in that said drying step (2) is carried out by a belt dryer. Method for producing insect larvae according to claim 1, characterized in that said drying step (2) is carried out by a fluidized bed dryer. Insect larvae production facility comprising a larvae rearing area (10) and equipment (22) for separating the larvae and their rearing environment, characterized in that it further comprises a dryer (21) arranged between said larvae rearing area (10) and said separation equipment (22). Insect larvae production plant according to the preceding claim, characterized in that said dryer ensures a reduction in the humidity level of the larvae breeding environment of at least 10 points. Insect larvae production plant according to claim 10, characterized in that said dryer (22) is a belt dryer. Insect larvae production plant according to claim 10, characterized in that said dryer (22) is a fluidized bed dryer.

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