Freeze induced texturization of alginate and protein for fish analogs

Abstract

The present invention relates to a method of making a plant-based fish analog, said method comprising mixing plant protein, alginate salt, and fat coated calcium salt in water to form a dough mixture; optionally emulsifying the dough mixture with oil or melted fat; transferring the dough mixture to a mold or a packaging; freezing the dough mixture so that the core temperature of the dough mixture reaches -10°C or less; thawing the dough mixture; and optionally cooking, chilling or flash freezing.

Description

[0001] Freeze induced texturization of alginate and protein for fish analogs

[0002] Introduction

[0003] Plant-based analogs are increasingly popular with consumers, including those who identify as flexitarian and want to consume more plant-based products. Compared to their plant-based meat counterparts, plant-based fish analogs are still relatively scarce. It has proven very challenging to bring both meaningful protein content which is close to real fish whilst maintaining the desired textural and visual characteristics.

[0004] An important feature of some plant-based fish analogs is that they should form flakes that break when pressure is applied by a fork. The creation of fibers mimicking flesh found in fish typically uses texturized vegetable protein (TVP) or high moisture extrudate (HME), but these both require extensive energy. Products currently on the market are often not very flaky. It is technically challenging to create layers in fillet format products that break under a fork.

[0005] There is a clear need to provide layered fillet format plant-based fish analogs which are flaky and break under a fork when consumed.

[0006] Summary of invention

[0007] The plant-based fish analog of the invention closely resembles animal versions of white fish and salmon. It is very close to these animal versions in terms of nutrition, particularly protein content. It is minimally processed because it is not extruded like many other plant-based fish analogs. It is characterized by its flaky and non-homogenous texture.

[0008] The plant-based fish analog is made by hydrating the soy protein and rice protein in water, and then generating an emulsion with the oil and adding the remaining dry powders to the mixture.

[0009] The dough is transferred to a fish mold followed by a slow freezing step so that the dough temperature reaches at least -10°C, preferably between -15 to -30°C, preferably about -20°C. Typically, this takes at least 9 hours depending on the thickness of the mold. If the freezing step is too fast, then it is more difficult to get large flakes. The first freezing step is a texturizing step. It was found that flakes can be obtained without the need of a directional freezing, thus simplifying the process. The addition of alginate allows for texturization even at low protein concentration. The type and concentration of alginate allows fine-tuning of the fish texture.

[0010] The incorporation of alginate also brings surprising benefits. During freezing, it was found to help concentrate the protein during the growth of ice crystals. Cooking in the presence of fat- coated calcium salt leads to a second gel network formation that strengthened the protein network. Typically, the salt is added last to help avoid early gelation. It was found that if the calcium salt was not added before freezing, then a liquid dough was obtained. Alginate reacts instantaneously with calcium ions, but the fat-coated calcium salt facilitated the creation of an alginate-protein network which not only benefits from the structuring role of alginate but then also from its gelling properties. The fat-coated calcium salt is a water-soluble calcium salt, preferably calcium lactate. The coating degree is at least 20%, preferably at least 50%. The fat coated calcium salt is used at between 0.5 and 4.5 wt%, preferably between 1.5 and 3 wt%.

[0011] It is important to note that the method does not involve alginate being used as the scaffold to create the fibers, followed by protein addition inside and gel formation. Rather, all components from the beginning are in the matrix and the proteins are successively gelled and then the alginate is gelled. Also, the method of the invention does not use directional freezing to create an aligned texture, but instead random flakes are formed, thus resulting in a superior product.

[0012] After freezing, the product is slowly thawed, typically for at least 2 hours depending on the thickness of the mold. Typically, it is then cooked in an oven until the core temperature reaches 72°C for at least 2 minutes. However, this cooking step was not found to make any difference to the product flakiness. The product can be consumed immediately, or chilled, or flash frozen for long storage.

[0013] Embodiments of the invention

[0014] The invention relates in general to a method of making a plant-based fish analog. In one embodiment, said method comprises mixing soy protein, rice protein, alginate salt, and fat coated calcium salt in water to form a dough mixture.

[0015] In one embodiment, said method comprises emulsifying the dough mixture with oil or melted fat.

[0016] In one embodiment, said method comprises transferring the dough mixture to a mold or a packaging.

[0017] In one embodiment, said method comprises freezing the dough mixture so that the core temperature of the dough mixture reaches -10°C or less.

[0018] In one embodiment, said method comprises thawing the dough mixture.

[0019] In one embodiment, said method comprises cooking, chilling or flash freezing.

[0020] In one embodiment, said method comprises: a) Mixing soy protein, rice protein, alginate salt, and fat coated calcium salt in water to form a dough mixture; b) emulsifying the dough mixture with oil or melted fat; c) transferring the dough mixture to a mold or a packaging; d) Freezing the dough mixture so that the core temperature of the dough mixture reaches -10°C or less; e) Thawing the dough mixture; and f) Optionally cooking, chilling or flash freezing.

[0021] In one embodiment, fat coated calcium salt is added after the alginate salt has been hydrated in the water.

[0022] In one embodiment, the freezing step d) is for at least 1 hour. In one embodiment, the freezing step d) is for at least 5 hours. In one embodiment, the freezing step d) is for at least 9 hours. In one embodiment, the freezing step d) is for between 1 to 20 hours. In an embodiment the dough is not heat treated before freezing the dough. In case of heating the dough before freeting a plain, homogeneous gel mass not having a desired flake structure is obtained.

[0023] In one embodiment, the total soy and rice protein content of the plant-based fish analog is between 4 to 16 wt% plant protein. The combination of soy and rice protein increased the gel strength and has only a minor influence regarding flake dimension compared to soy protein alone.

[0024] In one embodiment, between 1 to 3.5 wt% alginate salt is mixed. In one embodiment, the alginate salt is sodium alginate. In one embodiment, the alginate salt is potassium alginate.

[0025] In one embodiment, between 1 to 3.5 wt% fat coated calcium salt is mixed. In one embodiment, the fat coated calcium salt is fat-coated calcium lactate.

[0026] In one embodiment, between 0.5 to 1.8 wt% gum, is mixed. In one embodiment, the gum is acacia gum.

[0027] In one embodiment, between 2 to 10 wt%, preferably between 2 to 5 wt% vegetable oil is added in step b).

[0028] In one embodiment, salt, flavours, and colours are mixed in step a) or step b), wherein the salt is a sodium salt or a citrate salt.

[0029] The invention further relates to a plant-based fish analog, said analog comprising between 4 to 14 wt% soy protein, rice protein, alginate salt, and fat coated calcium lactate.

[0030] In one embodiment, the plant-based fish analog is obtainable a method according to the invention.

[0031] In one embodiment, the analog further comprises acacia gum.

[0032] In one embodiment, the dough mixture is further layered with a fat mimicking dough, for example an emulgel.

[0033] In one embodiment, the plant-based fish analog is vegan.

[0034] In an embodiment, the method of making a plant-based fish analog does not comprise any further hydrocolloid. In an embodiment, the method of making a plant-based fish analog does not comprise any further hydrocolloid selected from the group of konjac glucomannan, cellulose, methylcellulose or a combination thereof. The incorporation of konjac glucomannan was found to increase the dough viscosity, decrease the gel strength, and decrease the formation of flakes. Therefore, the method of making a plant-based fish analog does not comprise konjac glucomannan.

[0035] Brief description of the figures

[0036] Figure 1. Flake formation induced by freezing prior to gelation.

[0037] Figure 2. Texture properties of frozen samples against cooked ones.

[0038] Figure 3. DSC values and ice crystal formation in alginate / protein doughs.

[0039] Figure 4. Impact of alginate structure and molecular weight on freezing.

[0040] Figure 5. Impact of alginate concentration on gel strength.

[0041] Figure 6. Impact of protein composition on gel hardness after freezing.

[0042] Figure 7. Impact of protein composition on the formation of flakes.

[0043] Figure 8. Impact of protein concentration on gel strength.

[0044] Figure 9. Impact of protein concentration on gumminess and flake formation.

[0045] Figure 10. Impact of hydrocolloid incorporation on gel strength after freezing.

[0046] Figure 11. Impact of oil on gel strength after freezing.

[0047] Figure 12. Visual effect of changing order of method steps.

[0048] Figure 13. Visual differences of homogeneous and flaky samples obtained by freezing.

[0049] Detailed description of invention

[0050] Alginate salt

[0051] The alginate salt can be defined according to certain parameters. The alginate salt may have a viscosity at 1% (in mPa.s) of between 50 to 600, or 200 to 400, or 350 to 550, or 50 to 100, or 400 to 600. The alginate salt may have a molecular weight (Mw in kDa) between about 297 to about 1387, or about 297, or about 343, or about 943, or about 1387. The alginate salt may have a polydispersity index (PDI) of between about 1.6 to about 4.2, or about 1.6, or about 1.8, or about 2.6, or about 4.2. The alginate salt may have a M / G ratio of between about 0.5 to 1.7, or about 0.5, or about 1.0, or about 1.7. The parameters may be measured by a method as described herein. The alginate salt may have parameters which are the same or substantially the same as alginate ingredient 1, 2, 3, or 4, as described herein.

[0052] Plant protein

[0053] The rice protein or soy protein may be in the form of a protein isolate. The water solubility (in %) of the rice isolate may be about 2. The water solubility (in %) of the soy isolate may be about 14.1 or about 21.4. The minimum gelling concentration (in %) at neutral pH of the soy isolate may be about 10.

[0054] Plant-based fish analog recipes

[0055] The plant-based fish analog may be made according to a method and with an ingredient list and with substantially the same amount of ingredients as described in any one of Tables 3 to 11 in the Examples.

[0056] The plant-based fish analog may comprise about 2 wt% alginate, about 6 wt% soy protein isolate, about 2 wt% sunflower oil, about 2 wt% fat-coated calcium lactate, and about 89.5 wt% water. The alginate may have substantially the same parameters as alginate 2 as described herein. The soy protein isolate may have substantially the same parameters as soy protein isolate 1 as described herein.

[0057] Samples may be frozen at about -20°C, for example in a blast freezer. This promotes gelation and flake formation. The samples may be frozen, for example, for at least 9 hours followed by thawing for at least 2 hours prior to cooking for flake generation.

[0058] Definitions

[0059] As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. The words "comprise," "comprises" and "comprising" are to be interpreted inclusively rather than exclusively. Likewise, the terms "include," "including" and "or" should all be construed to be inclusive, unless such a construction is clearly prohibited from the context.

[0060] The compositions disclosed herein may lack any element that is not specifically disclosed. Thus, a disclosure of an embodiment using the term "comprising" includes a disclosure of embodiments "consisting essentially of and "consisting of the components identified. Similarly, the methods disclosed herein may lack any step that is not specifically disclosed herein. Thus, a disclosure of an embodiment using the term "comprising" includes a disclosure of embodiments "consisting essentially of" and "consisting of" the steps identified.

[0061] The term "and / or" used in the context of "X and / or Y" should be interpreted as "X," or "Y," or "X and Y." Where used herein, the terms "example" and "such as," particularly when followed by a listing of terms, are merely exemplary and illustrative and should not be deemed to be exclusive or comprehensive. Any embodiment disclosed herein can be combined with any other embodiment disclosed herein unless explicitly stated otherwise.

[0062] As used herein, "about" and "substantially" are understood to refer to numbers in a range of numerals, for example the range of -10% to +10% of the referenced number, preferably within -5% to +5% of the referenced number, more preferably within -1% to +1% of the referenced number, most preferably within -0.1 % to +0.1 % of the referenced number.

[0063] As used herein, the term "gel" is defined as a 3 dimensional network of proteins in water.

[0064] A vegan product is defined as being devoid of animal products, for example devoid of dairy products and meat products. A vegan fish analogue product of the invention has the look, taste, and texture which is close to the real fish version.

[0065] A heat gelling protein is protein which can form a heat induced gel at neutral pH when the protein concentration is between 4% and 15%.

[0066] The invention will now be illustrated by way of examples, which should in no way be thought to limit the scope of the invention as herein described.

[0067] EXAMPLES Example 1

[0068] Materials and methods

[0069] The following ingredients were purchased and characterized as described below.

[0070] Alginates

[0071] Table 1

[0072] The weight averaged molecular weight (mw) and the polydispersity index (PDI) were measured by size exclusion chromatography (SEC) using an Agilent 1200 HPLC coupled to three detectors: multi-angle laser light scattering (MALLS) operating at eighteen angles (Dawn Heleos II, Wyatt, CA, USA), on-line viscosimeter (VISCOSTAR II, Wyatt, CA, USA) and differential refractometer (Optilab T-rEX, Wyatt, CA, USA). The system was composed of one Tosoh PWH pre-column followed by three columns in series (Tosoh G6000PW, G3000PW and GP2500). All samples were prepared in 0.1 M NaNOs and 0.05M LiCI solution (2 mg / mL), filtered through a 0.22 pm filter and eluted through the system with 0.1 M NaNOs and 0.05M LiCI solution containing 0.05% ProCiin 2000 at a constant flow rate of 0.6 mL min-1and 30 °C. Data were analysed using ASTRA software 8.1.0 (Wyatt Technologies, Santa Barbara, CA).

[0073] The M:G ratio was measured by1H NMR following ASTM standard F2259.

[0074] Proteins

[0075] Table 2 TA measurements

[0076] Texture measurements of unlayered alginate gels were performed with a TA.HDplusC (Stable Microsystems, UK) with a 50kg load cell. The dough was prepared in a Thermomix as described previously, placed in a piping bag, and vacuum-sealed twice to remove as much air as possible. The bags were used to fill a metal ring (3.2 cm diameter, 2cm height), ensuring that no air bubbles were created, and the samples were trimmed to ensure homogeneous height and sample preparation. Samples were cooked in an oven for 50 min at 100°C and left in a fridge overnight prior. The next morning a texture profile analysis (TPA) measurement was done with a P70 plate at a test speed of 1 mm / s and with a 70% compression (two cycles, 5 sec waiting time). The parameters obtained were firmness (the force applied in the first cycle that is required to compress by 70%) and gumminess (the energy needed to disintegrate a semi-solid food until it can be swallowed). All measurements were performed at least 10 times at room temperature. Data was acquired and processed with TA exponent software.

[0077] The freezing parameters (melting point Tmand Tm', glass transition Tg') were measured by DSC with a DSC Q2000 (TA instrument) as described in literature.

[0078] Example 2

[0079] Impact of freezing prior to alginate gelation

[0080] The following recipe was prepared:

[0081] Table 3

[0082] The soy protein was hydrated in water for 15 min at low shear. The oil was then added and an emulsion was generated at maximum shear for 2 min. The alginate and salt were added and hydration was pursued for 20 min. The fat-coated calcium lactate was added last, then the dough was transferred into molds and either: 1) cooked in a fan oven (100°C for 50 min); or

[0083] 2) slowly frozen at -20°C, thawed the next day for 3 hrs, and then cooked in a fan oven 100°C for 50 min

[0084] The samples that were cooked were a plain, homogeneous gel mass. The samples that were stored in the freezer first had a layered texture with flakes that presented a particular breaking ratio and supported a compression test (75%). The hardness of both samples (cooked or frozen) was comparable, but the elasticity and gumminess increased a lot.

[0085] The glass and melting transition of the dough are important parameters in freeze-induced gelation of proteins and were measured by DSC. For the alginate dough, optimum big ice crystal formation should occur between -28 and -40°C (Figure 2). Samples frozen at -40°C in a blast freezer did not lead to gelation or flake formation, while samples frozen at -20°C did. A minimum of 9 hrs was required for the formation of flakes using the salmon fish molds as well as a slow thawing (min 2 hrs) prior to cooking for flake generation.

[0086] Figure 3 shows the DSC values for alginate dough (2% alginate 3, 2% oil, 6% soy protein 2, 2% rice protein, and 0.5% NaCI). The Tm(in °C) is -27.62 ± 0.13, the Tm' (in °C) is -28.99 ± 0.12, and the Tg(in °C) is -54.95 ± 1.97.

[0087] Example 3

[0088] Samples without calcium

[0089] The following recipe was prepared:

[0090] Table 4

[0091] The soy protein was hydrated in water for 15 min at low shear. The oil was then added and an emulsion was generated at maximum shear for 2 min. The alginate and salt were added and hydration was pursued for 20 min. The fat-coated calcium lactate was not added, then the dough was transferred into molds and slowly frozen at -20°C, thawed the next day for 3 hrs then cooked in a fan oven 100°C for 50 min. After thawing the samples were still liquid. No flakes were visible. The samples were very liquid and flowed immediately when removed from the molds.

[0092] Example 4

[0093] Impact of type of alginate

[0094] The impact of the type of alginate used was tested with the following recipe and prepared as described in example 2.

[0095] Table 5

[0096] The alginate structure and molecular weight was varied. Samples were prepared as described previously. High mannuronic (M) alginates (1) gave low gel strength and small flakes, when higher guluronic (G) alginates gave stronger sample (3, 4). Low molecular weight alginates (3) was preferred over higher Mw for flakes formation. Shorter chains may be more flexible and favour water mobility and ice crystal formation during freezing, giving bigger flakes. The impact of the alginate concentration was performed with alginate 2 (M=G). The following recipes were investigated, and samples were prepared as described earlier:

[0097] Table 6 Increasing the amount of alginate improved gel strength but decreased the size of the flakes formed. Without wishing to be bound by theory, that could be due to a lower amount of free water in the system, thereby decreasing the formation of ice crystals.

[0098] Example 5

[0099] Impact of protein type and concentration

[0100] The impact of the type and concentration of protein used was tested on the following recipes as described above.

[0101] Table ?

[0102] The soy protein used impacted on both the gel strength (TA hardness, Figure 6) and structure (flakes, gumminess, TA test Figure 7). Soy protein isolate 2 (high solubility) gave weaker gels, more mushy, and with almost no flakes (gumminess lower than for cooked samples). Soy protein isolate 1 favored gel strength but also the formation of flakes (increased gumminess / elasticity of samples). Mixing both soy gave intermediate properties, maintaining flake formation but decreasing gel strength, bite, and initial viscosity. The incorporation of rice increased gel strength and had minor impact on flake dimension.

[0103] In a second experiment, the best soy protein (1) was selected and the concentration was varied to see the impact on flake formation. The following recipe was chosen:

[0104] Table 8

[0105] Higher protein concentration improved the hardness and maintained the formation of flakes up to a critical concentration of 10%, after which samples turned mushy and no flakes were formed (decreased of strength and gumminess values respectively according to TA - see Figure 8 and Figure 9). Increasing the concentration of soy protein isolate 2 did not bring any benefit.

[0106] Example 6

[0107] Effect of addition of hydrocolloids The following recipes were produced as described in Example 1:

[0108] Table 9

[0109] The incorporation of konjac was found to increase the dough viscosity, decrease the gel strength, and decrease the formation of flakes. Acacia gum decreased the initial dough viscosity, so that the concentration of alginate was increased. This was observed in other processes and was attributed to incompatibility between acacia gum and proteins and alginates, leading to phase separation and decreasing the initial viscosity. Acacia gum did not have any impact on the flakiness but increased the overall bite. Example 7

[0110] Impact of TVP addition

[0111] The alginate binder was prepared according to recipe 1 and mixed with hydrated TVP (prehydrated for 10 min in water, 1:1 weight ratio). TVP could be well bonded to the dough but it destroyed the formation of flakes and brought mushiness. Different TVP sizes were used but always with the same results.

[0112] Example 8

[0113] Impact of oil

[0114] The following recipes were prepared as described above:

[0115] Table 10

[0116] Increasing the amount of oil gave stronger gels. When no oil was present samples were mushy and had very small flakes at this low protein concentration. When higher protein concentrations were used, bigger flakes were obtained. High amount increased gel strength, but when the oil was too high, then the flakes were smaller.

[0117] Example 9

[0118] Combination of freezing and layering

[0119] The following recipes were prepared:

[0120] Table 11

[0121] The flesh mass was prepared as described above.

[0122] The connective tissue dough was made as follows: soy protein isolate 1 (9%, 90g) was suspended in demineralized water (71%, 710g) for 15 min, then high oleic sunflower oil (20%, 200g) was added slowly and the speed was increased to the maximum progressively and maintained for 1 min. The dough was mixed with a spatula and mixed to maximum speed for 1 min one more time.

[0123] For the layering, both doughs were transferred in piping bags and dosed alternatively in a mold, frozen at -20°C for at least 18 hrs, thawed for 2 hrs and cooked in a fan oven at 100°C for 50 min. The connective tissue dough was very thin and would melt upon cooking, creating flakes of a white fish, whilst the freezing prior to cooking would produce small fibers signature of fish filet.

Claims

Claims1. A method of making a plant-based fish analog, said method comprising a) Mixing soy protein, rice protein, alginate salt, and fat coated calcium salt in water to form a dough mixture; b) emulsifying the dough mixture with oil or melted fat; c) transferring the dough mixture to a mold or a packaging; d) Freezing the dough mixture so that the core temperature of the dough mixture reaches -10°C or less; e) Thawing the dough mixture; and f) Optionally cooking, chilling or flash freezing; wherein the dough is not heat treated before freezing the dough.

2. The method of making a plant-based fish analog according to claim 1, wherein fat coated calcium salt is added after the alginate salt has been hydrated in the water.

3. The method of making a plant-based fish analog according to any one of claims 1 and 2, wherein the freezing step d) is for at least 1 hour, preferably at least 5 hours, more preferably at least 9 hours.

4. The method of making a plant-based fish analog according to any one of claims 1 to 3, wherein the soy and rice protein content of the plant-based fish analog is between 4 to 16 wt%.

5. The method of making a plant-based fish analog according to any one of claims 1 to 3, wherein the plant-based fish analog does not comprise any further hydrocolloid.

6. The method of making a plant-based fish analog according to any one of claims 1 to 5, wherein between 1 to 3.5 wt% alginate salt, for example sodium alginate or potassium alginate, is mixed.

7. The method of making a plant-based fish analog according to any one of claims 1 to 6, wherein between 1 to 3.5 wt% fat coated calcium salt, preferably fat-coated calcium lactate, is mixed.

8. The method of making a plant-based fish analog according to any one of claims 1 to 7, wherein between 0.5 to 1.8 wt% gum, preferably acacia gum, is mixed.

9. The method of making a plant-based fish analog according to any one of claims 1 to 8, wherein between 2 to 10 wt%, preferably between 2 to 5 wt% vegetable oil is added in step b).

10. The method of making a plant-based fish analog according to any one of claims 1 to 9, wherein the dough mixture is further layered with a fat mimicking dough, for example an emulgel.

11. The method of making a plant-based fish analog according to any one of claims 1 to 10, wherein salt, flavours, and colours are mixed in step a) or step b), wherein the salt is a sodium salt or a citrate salt.

12. A plant-based fish analog, said analog comprising between 4 to 14 wt% soy protein, rice protein, alginate salt, and fat coated calcium lactate.

13. The plant-based fish analog according to claim 12, wherein the analog further comprises acacia gum.

14. The plant-based fish analog according to any one of claims 12 to 13, wherein the plantbased fish analog is vegan.

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