The invention relates to an apparatus and method for separating sea-squirt organisms (ascidians), and more specifically solitary ascidians, in two different fractions, viz. a first fraction containing the body, and a second fraction containing the inner tunic and the outer tunic of the ascidians. According to the invention sick individuals are detected and removed from the ascidian raw material in order not to contaminate the resulting body fraction, which fraction can be used as fish and animal feed.

State of art The general body organization of ascidians includes an inner body where digestive and reproductive organs are located, and an outer layer - the tunic. The tunic is made up largely of tunicin which is a cellulose substance very similar to the cellulose of terrestrial plants. The tunic consists of several layers. For practical reasons, we divide the tunic into a gelatinous inner layer consisting almost of 100 % cellulose, henceforth referred to herein as inner tunic, and an outer test layer, respectively. Test is the biological term for a harder outer shell or layers in some organisms. The test of ascidians is only a few millimeters thick, leathery or papery, and usually dirty and overgrown with epiphytic microalgae. Hereafter is the test referred to as outer tunic.

WO2013088177 describes the use of parts of the sea squirt Ciona intestinalis as fish and animal feed. The demand for mari ne fish feed is very large in the world. Fish farming industry seeks to re- place marine feed ingredients with vegetable feed ingredients since fishing the raw material negatively affects fish populations and ultimately is ecologically questionable. However, this is problematic because fish need marine fatty acids and proteins in their diets to be able to grow optimally. At a too high ratio of vegetable raw materials, the quality of the fish feed decreases. One estimate is that it takes at least 1.5 kg of feed fish per kg of farmed trout, but this number varies greatly between dif- ferent regions and species cultivated. Zhao scrutinize in "Towards Large-Scale and Feasible Exploitation of Tunicate Cellulose and Cellulose nanocrystals for Different Applications", PhD thesis, KTH Royal Institute of Technology in 2015, with included manuscripts and articles, ISBN 978-91-7595-576- 6, ISSN 1654-1081 very thoroughly the feed properties of Ciona intestinalis and characterizes the inner parts of the animal body, as a very good fish feed which consisted of 62% protein, 20% fat and 6% carbohydrate. Other nearby uses for ascidian biomass is feed for other animals or for human consumption. According to Zhao the tunic of Ciona intestinalis contains nearly 100 % cellulose with a number of positive material properties with respect to cellulose; e.g. the cellulose has a high polymerization degree, a high surface area, a high ratio of length to diameter of the fibres, high degree of crystallinity and good mechanical strength properties. Among the organism group of tunicates ( Urochordata) all the animals in the organism classes sea squirts, (Ascidiacea) and salps (Thaliacea), respectively, produce a tunic of cellulose.

KR20090089956 discloses a method of producing a pharmaceutical for diabetes from sea squirts.

J P2004298161 descri bes multiple uses of sea squirts. WO2011028163 describes the use of Ciona intestinalis to produce biogas. US20140020283 discloses a method of producing a biofuel based on extracts from Ciona intestinalis. CN204362751 discloses a method for separating sea cucumbers from sea squirts.

Methods and devices for separating parts of fish and shell fish are known in the art, e.g.

US5005258 discloses an apparatus for eviscerating scallops, US4481693 discloses an apparatus for treating fish carcasses for separating flesh from frames and skins. US20090325474A1 discloses an ap- paratus processing seacucumbers. US3947921 discloses an apparatus for cleaning marine animals of the mollusc type, but none of which is however suitable for processing ascidians.

Sea squirts have many different uses and it would be desirable to effectively make use of the sea squirts biomass.

A purpose of the invention is to provide an apparatus and a method for producing fish feed from sea squirts.

Summary of the invention

The present inventors have found that the outer tunic contains acidic or non-palatable substances, making the ascidian less suited for fish feed. It has also been found that sick individuals of ascidians tend to contaminate the resulting body fraction, making it less palatable, especially for fish. Accordingly, the invention provides an apparatus and method for producing fish feed from ascidians, wherein the tunic and sick individuals are removed from the harvested ascidians.

In a first aspect, the invention relates to an apparatus for industrial scale separation of ascidians A body parts from each other. The inventive apparatus is provided with means for detecting and removing sick individuals A2 from the ascidians A, so as to obtain a purified ascidian raw material Al, and then separates whole organisms into two different fractions: body B; and a tunic fraction containing inner and outer tunic C and D, respectively. The apparatus according to the invention comprises in its most general embodiment a first roller pair 2 having a roll gap selected from the range of from 0 to 3 mm. The roller pair's longitudinal axis has an inclination in respect to the horizontal plane so that material B remaining on the rollers is led away from the roller pair via the lower end of the rollers. The apparatus is provided with a detection and sorting device 6 for removing sick individuals A2 before reaching the first roller pair 2 by illuminating individually transported ascidians A in a chute with white light 14 and a light meter 16 for measuring the reflected green light, at 520-565 nm, from the ascidians A thereby detecting sick or dead ascidians A2. A sorting device 17 configured to remove thus-detected sick or dead ascidians A2 before they reach the roller pair is also provided in the apparatus. The sorting device 17 is activated by a measured signal of green light in the wavelength 520-564 nm higher than a threshold value.

The two wanted fractions B and C have different commercial usage areas and there is a huge economic benefit in separating them in only one process. The body B is used for animal feed or food as it is very rich in marine fats and proteins, and does not contain the acidic or unpalatable substances found in the outer tunic D. The inner tunic C consists mostly of pure cel lulose, which is used in sev- eral technical applications such as textile fibres or plastics raw material .

Accordingly, in one embodiment the apparatus is configured to further separate the inner tunic C from the outer tunic D, which apparatus further comprises a second pair of rollers 3 for separating inner tunic C from outer tunic D having a roll gap selected from the range of from 0 to 1 mm, which roll gap is smaller than that of the first roller pair 2, wherein the first roller pair is an upper roller pair, and the second roller pair is a lower roller pair, the two roller pairs being essentially parallel to each other, said lower roller pair being located so that material (C, D) passing through the upper roll gap by gravity falls down to the second roll gap.

Such embodiment allows for a more efficient use of the ascidian raw material A.

The inventive apparatus is a mechanical construction to avoid using chemical substances in the separation. The apparatus is preferably designed to be used on board a ship where the separation is conducted either directly after harvest or at an appropriate time thereafter.

I n another aspect the invention relates to a process for separating bodies B of solitary ascidians Al comprising the steps of: (a) providing ascidians A; (b) detecting sick ascidians A2; (c) separating detected sick ascidians A2 from ascidians A, to obtain a purified ascidian fraction Al; (d) passing the purified ascidian fraction Al obtained in step (c) to a pair of rollers 2 having a roll gap within the range of from 0 to 1 mm, for separating the body B from the ascidians A; (e) collecting the body fraction B which is retained on the roller pair; and, (f) allowing the remaining parts (inner tunic C and outer tunic D) of the ascidians Al to pass through the roll gap. The method may suitable be carried out using the device described in this invention, and can be used on board a ship where the separation is conducted, either directly after harvest or at an appropriate time thereafter.

The inventive method is preferably carried out using water as the only addition to the input of as- cidians A.

In a preferred embodiment of the method sexually mature ascidians A are used, since the body B of these animals contains higher contents of protein and fat, respectively.

In one embodiment of the inventive method the inner tunic C is further separated from the outer tunic D. In such embodiment the method further comprises the following steps: (g) passing the inner and outer tunic (C and D) obtained in step (f) to a second pair of rollers having a smaller roll gap selected from the range of from 0 to 1 mm for separating the inner tunic C from the outer tunic D; (h) collecting the inner tunic fraction C which is retained on the second roller pair; and, (i) allowing the remaining outer tunic D to pass through the roll gap of the second roller pair.

In conventional land-based production, of corresponding material fractions obtained in this inven- tion, negative effects arise such as competition with land usage for food production as well as usage of pesticides and the use of plant nutrients which leak from agriculture and causes eutrophication of lakes and seas. This problem is avoided by localizing the raw material production to the sea, and where the raw material production is the growth of filter-feeding invertebrates. These filtering animals grow by filtering out plankton and bacteria from the sea and use it as food for growth, meas- ured as increase in weight of biomass per area and year, which is very high in the upper productive part of the ocean. With the present invention, valuable material fractions can be obtained without the negative effects associated with land-based production.

Preferred embodiments and advantages thereof are described in the following description and claims. Brief description of the drawings

FIGURE 1 shows a preferred embodiment of the device according to the invention, where A designates incoming biomass, 10 an exit opening for the first fraction B (body), chute 12 for fraction B, 11 exit opening for the second fraction C (inner tunic), chute for fraction C, third fraction D (outer tunic), 1 housing that encloses the two roller pairs, 2 upper roller pair, 3 lower roller pair, 4 scrapers located at both roller pairs, 5 water spray nozzles located at both roller pairs, and 6 detecting and sorting de- vice located at the entry of biomass A, where sick individuals are detected and sorted out as a fraction A2, and where Al is the purified fraction that is obtained and that is transported to the roller pairs.

FIGURE 2 show a section of FIGURE 1 as shown by the sectional line I-I pinpointing the rotational direction of the rollers and a detail of one embodiment of the detection and sorting device 6 in sectional view showing a white light source for reflected light 14 and the light meter 15. The ascidian material is transported in a chute 16 and sick individuals are sorted as discharge A2 using the opena- ble part 17 of the chute.

FIGURE 3 shows a schematic description of a sea-squirt, where D designates the outer tunic, C designates the inner tunic and B designates the body.

Detailed description of the invention

Marine biomass - Ascidians

Sea squirts, Ascidiacea, is a class of tunicates with approximately 2,300 species worldwide, of which about 50 are living at the Swedish west coast. They are sessile, solitary or colony forming filter feeders. The body is sack like and completely surrounded by the tunic. As an example, the sea squirt Ciona intestinalis L. may grow in very high abundances and has been reported in densities of over 5,000 individuals per m ¹ . The weight of biomass has been measured to ~7 kg of dry weight/m ² in Norwegian waters and to 200 kg wet weight/m ² in Canadian waters. Applying a dry matter content of 4 %, this would correspond to a value of 8 kg dry matter/m ² . They live by filtering plankton from the water and have a very fast growth rate compared to many other animals. They may have a daily length growth of 2-3% and a doubling of weight in 10 days. In boreal waters Ciona intestinalis propagates twice per year and in warmer water three times, possibly four times. The growth rate of Ciona intestinalis has also been measured in the ocean by the inventor and found to be 8.5 cm (n = 350, S.D. = 3.2 cm) in 93 days and as a growth in the biomass, measured as wet weight per m ² of 33 kg during the same time (location: Lysekil, Sweden, from May 2009 to August 2009, depth 1-2 meters on vertical concrete foundations, approximate salinity 20-34 psu, approximate temperature of 10- 20°C).

As well as harvesting the species that we have practical experience of, i.e. Ciona intestinalis, which is suitable to cultivate in Swedish waters, other solitary tunicates could also be cultured where the conditions are favourable for such species or if Ciona intestinalis is not naturally existing in the area. White the invention is described with particular reference to Ciona intestinalis, the device can equally well separate other solitary ascidians from the class Ascidiacea. Solitary ascidians are an established biological term meaning those ascidians who do not share any part of the body with other individuals. Non-solitary types of ascidians are termed compound ascidians in English and they share different degree of tissue between individuals (e.g. Botryllus schlosseri). As examples of solitary ascidians the following can be mentioned, the whole genus Ciona, such as the species Ciona Edwardsi, Ciona fascicularis, Ciona geiatinosa, Ciona imperfecta, Ciona intestinalis, Ciona mollis, Ciona savignyi, Ciona robusta, Ciona longissima, Ciona antarctica, Ciona pomponiae, Ciona roulii, Ciona sheikoi and species of sea pineapple, Halocynthia aurantium, Styela clava, and the genus Ascidia in general. Parasites and other diseases reduces the quality of ascidians as raw material for various uses. The tissue of the ascidians is broken down and the valued properties are destroyed, and the taste and smell of a parasitized ascidia is negatively affected, and there is a risk that the parasite-infected or sick individuals can spread disease to the animals feeded with ascidia feed. We have in our own studies of Ciona intestinalis, intended to be used as fish feed, measured that a certain proportion of Ciona populations always are infected, with a so far unidentified pathogen characterized in that Ciona-ani- mal becomes clearly greenish, or more precisely have colours in the visible wavelength of ~520-565 nm, and very malodorous. The smell is reminiscent of poorly managed wounds. Other parasites affecting Ciona intestinalis may be mentioned, for example the apicomplexan parasites Cardiosporid- ium cionae, Lankesteria ascidiae and Haplosporidium ascidiarum. Apparatus for separation

The apparatus is provided to separate solitary ascidians into two different fractions, and is based on a roller pair 2. In embodiments of the apparatus for separating solitary ascidians into three different fractions, the apparatus is based on two roller pairs, 2 and 3, respectively, where the first roller pair 2 has a wider roll gap and the second roller pair 3 has a smaller roll gap. The roller pairs may e.g. be made of plastic or metal . The surface of the rollers of the roller pairs must have enough friction so the ascidians are transported through the roller pairs. The rollers can be provided with a surface coating of a higher coefficient of friction . In one embodiment rubber is used as a surface coating to promote the transport of ascidian material through the roll gap. In another embodiment the rollers are coated with a soft coating preferably made of natural or synthetic rubber with a hardness of SO- 90 in the Shore A scale.

For ease of transport of the retained fraction B, and C, respectively, from the roller pairs, the roller pairs' longitudinal axes are inclined in relation to the horizontal, preferably at an angle of 20- 50°, more preferably 30-40°. A chute 12, and 13, respectively, is preferably arranged at the lower end of each roller pair where the retained fraction is led away from the roller pair.

In order to facilitate removal of the retained fraction from each roller pair, the apparatus preferably comprises nozzles 5 for ejecting a jet of water onto the upper part of each roller pair. In embodi- ments with chutes the water jet transports the retained fractions B, and C, respectively, down to the chute, which in turn is configured to transport the retained fraction, preferably via an opening 10, and 11, respectively, on the side of the housing 1, to be collected outside the apparatus.

The third fraction of outer tunic D passing both roller pairs is collected below the second roller pair 3 to be transported out of the apparatus, for example through a hole (not shown) i n the housing 1, or in a variant of the embodiment through a hole underneath (not shown) in the housing.

In embodiments with a housing 1 an opening is located in the top part of the housing 1 and is constructed so that material A to be separated is led by gravity and lands centred on the upper roller pair. As shown in FIG 1, each roller of the two pairs of rollers are preferably provided with scrapers 4 to scrape off materials adhering to the rollers, and the angles of the scrapers is preferably aligned and located so that the scraped material lands on the lower roller pair 3 or collected under the lower roller pair 3.

The quality of the ascidians deteriorates if the animals are sick or parasitized and the apparatus is therefore equipped with a light source 6 for illuminating the ascidian material A with white light and a light meter for measuring the proportion of reflected green light in wave lengths of 520-565 nm from the ascidians and a thereto connected separation device which removes green ascidians A2 before reaching the upper roller pair 2, so that a purified fraction Al is obtained and is further processed in the inventive apparatus and method. A diseased or parasitized animal can be detected by the device when provided with one or two light sources producing white light from above 14 the transportation chute 16 and a light meter for measuring the proportion transmitted light 15, and a thereto connected separation device that removes diseased ascidians before they reach the roller pairs by closing an openable part 17 of the chute 16 which makes a sick individual to be transported out of the apparatus as fraction A2 when the openable part is closed. The chute 16 is constructed to fit individual ascidians with a diameter of the chute slightly exceeding the maximal radius of the harvested ascidians and is in the range of 20-60 mm. The material of the chute can be any suitable mate- rial but preferred materials are stainless steel or plastics.

When harvested material A contains mussels or other organisms with hard shells, the apparatus may preferably be equipped with grids (not shown) for removing unwanted hard material such as clams, snails or rocks, where the distance between the grid bars can be selected to be from 15 mm to 30 mm depending on the size of the sea squirts to fall through the grid and of the hard material to be retained on the grid, respectively. An alternative or additional device to screen out undesirable material can be mounted before the separation device and is designed in such a way that the unwanted material is separated through differences in density in comparison to that of the ascidians, which are to be retained, wherein the device comprises a water tank with overflow separator where mussels and other heavy materials sink into the tank and ascidians pass over the water tanks' overflow opening and is led into the separation device opening and the first roller pair 2.

To verify the inventive separation apparatus as described herein fish was fed with the body fraction of Ciona intestinalis, that is, the first separated fraction B of the presently disclosed invention. As comparison fish was fed with non-separated Ciona intestinalis, namely fraction A or whole Ciona intestinalis. The nutritional composition, expressed as percentage of dry matter, of the whole animal A was 35% protein, 24% carbohydrate and 4% fat. Feed made of the entire animal was not eaten by fish (investigated with the species herring, cod, catfish, pollock, small-mouthed wrass [Centrolabrus exoletus] and goldsinny [Ctenolabrus rupestris]). The nutritional composition of body fraction B, ex- pressed as a percentage of dry matter for the produced body fraction B, was 62% protein, 5% carbohydrates and 7% fat, and was willingly eaten by the investigated fish species above. The experiment was carried out both with fresh and dried feed, without differences in willingness to eat between the investigated fish species. In trials using only sexually mature Ciona intestinalis a higher protein and fat content was obtained in the feed and this fraction was willingly eaten by the investigated fish spe- cies above . The degree of sexual maturity is determined by how much, and the degree of maturity, of gonads there are in the animal. Since many species of ascidians are hermaphrodites and thus produce both eggs and sperm in the same individual this tissues contain higher levels of protein than other tissue. As an example, the results of Zhao above report a protein content, measured as ash- free dry weight, of 89% in the ovaries compared to 50% of the entire animal. In one embodiment of the inventive method harvesting ascidians when their gonads are well developed will produce a more protein-rich fraction suitable for fish feed. Ascidians are preferably harvested when the weight of the gonads exceeds 10% of the body wet weight.

When the inner tunic C is not separated from the body B, the fishes tested in the verification test of this invention did not willingly eat the body B. The inventors concluded that the inner tunic C did have some taste or other characteristic that made the feed untasty for the different fish species tested. When the inner tunic C was fully removed from the body B, the fish willingly ate the produced feed. This implies that it is highly preferably to remove all the parts of cellulosic tunic, both inner tunic C and outer tunic D, especially when the body fraction B is intended for use as fish feed. In embodiments of the apparatus wherein the second roller pair 3 is omitted, the associated chute 13 and, where appropriate, the opening 11 in the housing and the lower water jets 5 may also be omitted.