METHOD FOR THE PRODUCTION OF PROTEIN-CONTAINING FOODS

Abstract

The present invention relates to a method for producing protein-containing foamed food products, comprising the steps: metering raw materials into an extruder, wherein at least one raw material is a protein, mixing the raw materials into the extruder to produce a mixture, extruding the mixture to produce an extrudate, and leading the extrudate out of the extruder through a cooling die with cooling of the extrudate to a temperature of less than 100° C., wherein pores are formed in a controlled manner in the extruder, by providing a gas, by introducing the gas into the extruder or by forming the gas based on a reaction of a gas-forming compound added as a raw material with a gas-releasing compound added as a raw material.

Claims

1.-17. (canceled)

18. A method for the production of protein-containing foamed food products, comprising: a) metering raw materials into an extruder, wherein at least one raw material is a protein, wherein a protein content in the raw materials, based on dry weight thereof, is greater than 50%, and a starch content in the raw materials, based on dry weight thereof, is not more than 50%, and the raw materials comprise at least one component which has a fiber content, b) mixing the raw materials in the extruder to produce a mixture, c) extruding the mixture to produce an extrudate, wherein the solids content of the extrudate is in the range from 20% to 60%; and d) leading the extrudate out of the extruder through a cooling die while cooling the extrudate to a temperature of less than 100° C., wherein a controlled pore formation is performed in the extruder by providing a gas, so as to provide after step d) a foamed product having a protein content in the range from 15-30 wt.-%, and a liquid content of 45-70 wt.-%.

19. The method according to claim 18, wherein the gas is provided in the extruder by introducing this gas into the extruder.

20. The method according to claim 19, wherein the gas is selected from the group consisting of CO.sub.2, N.sub.2, N.sub.2O or SO.sub.2.

21. The method according to claim 20, wherein the gas is introduced into the extruder in an amount from 0.01 to 5% by weight, based on the total weight of the raw materials metered in step a).

22. The method according to claim 18, wherein a specific mechanical energy input introduced by the extruder is in the range from 10 Wh/kg to 120 Wh/kg.

23. The method according to claim 18, wherein a temperature in the extruder is set in the range from 80° C. to 180° C.

24. The method according to claim 18, wherein oil is injected into at least one of the distribution body of the extruder and the cooling die itself.

24. The method according to claim 18, wherein the foamed product has distributed pores having a diameter of approximately 0.1-1 mm with a narrow size distribution and distributed closed cavities.

26. The method according to claim 18, wherein the foamed product has a maximum force in the range from 10-50 N in longitudinal direction (F.sub.L) and in the range from 10-90 N in transversal direction (F.sub.T)

27. A protein-containing foamed food product, obtainable according to the method according to claim 18, wherein the foamed food product has a protein content in the range from 15-30 wt.-% and a liquid content of 45-70 wt.-%.

28. The protein-containing foamed food product according to claim 27, wherein said product is an alternative meat product.

29. The protein-containing foamed food product according to claim 28, wherein the L* value of the foamed food product deviates from the L* value of a meat product by no more than 20%.

30. The protein-containing foamed food product according to claim 29, wherein said product has a fibrillar, porous, longitudinally oriented and cross-linked structure.

31. The protein-containing foamed food product according to claim 30, wherein said product exhibits a maximum force in the range from 10-50 N in longitudinal direction (F.sub.L) and in the range from 10-90 N in transversal direction (F.sub.T).

32. The protein-containing foamed food product according to claim 27, wherein said product has a porous structure with distributed pores having a diameter of approximately 0.1-1 mm with a narrow size distribution, and with distributed closed and interconnected cavities.

33. The protein-containing foamed food product according to claim 27, wherein said product is a food product which comprises at least one vegetable protein, insect protein, cell protein, or a mixture of different proteins.

Description

[0099] The present invention is explained in the following with reference to non-limiting drawings and examples. Shown are:

[0100] FIG. 1 a comparison of the color appearance of a product produced according to the invention with a product produced conventionally (without foaming) and a reference sample (chicken breast)

[0101] FIG. 2 a comparison of the fibrillar structure of a product produced according to the invention with a product produced conventionally (without foaming) and a reference sample (chicken breast)

[0102] FIGS. 3a and b a comparison of the porosity of a product produced according to the invention with a product produced conventionally (without foaming)

[0103] FIGS. 3c and d a further comparison of the porosity of a product manufactured according to the invention with a product manufactured conventionally (without foaming)

[0104] FIG. 4a a comparison of the texture values of a product produced according to the invention with a product produced conventionally (without foaming)

[0105] FIG. 4b a comparison of the anisotropy index values of a product produced according to the invention with a product produced conventionally (without foaming).

[0106] FIG. 5a to c a comparison of the appearance of products produced according to the invention with different gas injection rates

[0107] FIG. 6 a comparison of the texture values of products produced according to the invention

[0108] FIG. 7a a fluctuating texture profile of a commercial snack product

[0109] FIG. 7b a fluctuating texture profile of a foamed product according to the invention

[0110] FIGS. 8a and b a microscopic image of the porosity of a product produced according to the invention

EXAMPLE 1

[0111] In a 30 mm twin-screw extruder from Bühler with an additional gas supply unit (on the penultimate barrel segment in front of the cooling die) and kneading/mixing element at the position of the gas supply unit, the following raw material was processed at 145° C., 380 rpm, and a temperature of the cooling die of 60° C.:

TABLE-US-00003 Pea protein isolate (Protein content ≥75% 43% dry weight) Pea fiber (fiber content ≥50% dry weight,  9% starch content ≤50% dry weight) Sunflower oil  2% Water 46%

[0112] The throughput was 30 kg/h. 23 g/min N.sub.2 having a pressure of 15-30 bar were introduced into the extrudate.

[0113] The protein-containing food produced had an overrun at the die outlet (that is, a height exceeding the height of the extruder outlet and thus an enlarged volume of the sample) of 100% and, after cooling to room temperature at normal pressure, shrank to an overrun of 30-60%. The protein-containing foamed food product thus produced had very homogeneously distributed pores having a diameter of approximately 0.1-0.3 mm with a narrow size distribution.

EXAMPLE 2 (COMPARISON)

[0114] Example 1 was repeated with the difference that no nitrogen was introduced into the extrudate.

Color Measurements

[0115] The products from Examples 1 and 2 were measured using a conventional spectrophotometer with SCI (Specular Component Included). The sample to be measured had such a layer thickness that there was no transmission of light through the sample material and the measuring opening was completely covered with sample material. Reflection measurements were performed using a d/8° measurement geometry and with daylight (D65). L*, a*, b*, and C* values were determined. The results are shown in Table 1 in the following.

TABLE-US-00004 TABLE 1 L* (D65) a* (D65) b* (D65) C* (D65) Example 2 55.61 ± 0.17 11.10 ± 0.11  26.55 ± 0.09 28.77 ± 0.04 Example 1 71.07 ± 0.16 7.22 ± 0.37 25.75 ± 0.87 26.74 ± 0.93 Reference 79.66 ± 0.04 1.53 ± 0.24 13.96 ± 0.59 14.04 ± 0.61 (chicken breast)

[0116] The extrudate according to Comparative Example 2 had the lowest L* value at 55.61 and was therefore the darkest of all samples. The inventive extrudate according to Example 1 had an L* value of 71.06 and thus came close to the L* value of the reference sample (chicken breast at 79.66).

[0117] The extrudate according to Comparative Example 2 also had the highest red component at 11.10, while the proportion in the inventive extrudate according to Example 1 was lower at 7.22. An a* value of 1.53 in the reference sample (chicken breast) indicates an only slight red cast in the sample.

[0118] The yellowness, expressed by the b* value, was relatively the same in the extrudate according to Comparative Example 2 and in the inventive extrudate according to Example 1 (at 26.55 and 27.75 respectively). The chicken breast as a reference had a b* value of 13.96.

[0119] The C* value describes the chroma and can be calculated from the a* value and the b* value. It was similar in the extrudate according to Comparative Example 2 and the inventive extrudate according to Example 1 (at 28.77 for Example 2 and 26.74 for Example 1). The chroma of the chicken breast was lower at 14.04.

[0120] These color differences are shown in FIG. 1. FIG. 1, on the left, shows the product produced according to Comparative Example 2, in the middle, the inventive product produced according to Example 1 and on the right, the reference sample (chicken breast). It can be seen that the sample according to Example 1 comes considerably closer to the appearance of the reference sample.

Fibrillar Structure

[0121] The fibrillar structure is intended to describe the differences in the muscle fiber structure in a piece of meat (here a chicken breast as a reference sample) compared to the fibrous structure which is achieved by the thermal texturing of plant proteins. For this purpose, the extrudates according to Examples 1 and 2 were ripped open and the internal structure was analyzed macroscopically and microscopically. The result is shown in FIG. 2.

[0122] The product produced according to Comparative Example 2 was clearly built up in layers, wherein the inner core was straight in length. The layers were placed around it one after another. This reflects the shear force that was exerted on the material in the process and the die. Due to the high moisture content of the sample, these layers were held together relatively compactly. However, as soon as the product produced according to Comparative Example 2 was dried out in the air, the individual layers clearly fell apart from one another.

[0123] The inventive product produced according to Example 1 had a structure similar to that of the product produced according to Comparative Example 2 with regard to the longitudinally oriented layers. However, there was no inner core, just a cavity. The layers had then been placed around this cavity by means of the shear force. In this sample, these layers were not placed very compactly with one another, but were interrupted by small cavities. This resulted in a porous structure. As soon as the inventive product produced according to Example 1 began to dry out, not only did the individual layers become more clearly recognizable, but also the porous structure and the crosslinking that took place as a result. The individual layers no longer fell apart from one another, but were linked to one another at some points. The fibrillar structure of the two textured samples was oriented longitudinally, corresponding to the die in the thermal process. The reference sample, the chicken breast, is visibly more compact and more complexly networked.

Porosity

[0124] A thin section of each sample was made and a contrast between sample and pores was created by means of transmitted light. The images were recorded and processed by means of a VHX 6,000 digital microscope from KEYENCE. The result is shown in FIGS. 3a) and 3b).

[0125] It can be seen that the porosity was very pronounced in the inventive product produced according to Example 1 and thus also ensured structural cohesion in the dried state. The individual cavities were closed and had a homogeneous distribution, wherein the cavities on the outer edge were smaller. The closer to the center, the larger the cavities. The average area of a cavity was 21,292±36,110 μm.sup.2 with an average minimum and maximum diameter of 125±73 μm.sup.2 or 239±153 μm.sup.2. The results are summarized in Table 2.

TABLE-US-00005 TABLE 2 Max Minimum Area Circumference diameter. diameter [μm.sup.2] [μm] [μm] [μm] Average 21192 866 239 125 Normal deviation 36110 791 153 73 Max. 721276 15354 2342 925 Min. 5683 274 91 35

[0126] The product produced according to Comparative Example 2 had only a slight irregular porous structure. Hardly any porosity was visible in the outer regions, while cavities were visible in the inner part. These are due to the layered arrangement during the process and underline the statement that the individual layers are poorly networked with one another and detach relatively quickly from one another after loss of moisture.

Texture

[0127] The maximum force (peak force) which is required to break up the structure of the products according to Examples 1 and 2 when cutting or biting was determined using a Warnzer-Brazler blade set with a “V” slot blade (https://textureanalysis-professionals.blogspot.com/2014/12/texture-analysis-in-action-blade-set.html). This analysis helps to quantify the cutting or biting property of the product. All texture analysis measurements were made at room temperature of 25° C.

[0128] The extruded samples were cut into square pieces of 30 mm×30 mm as part of sample preparation for the texture analysis. The samples produced according to example 1 and 2 having a thickness of 13-16 mm (Ex. 1) and of 10 mm (Ex. 2) were cut transversally (right-angled to the flow direction of the extruded strand (F.sub.T) as well as cut parallel to the flow direction of the extruded strand (F.sub.L), and the respective maximum force (peak force) was determined and expressed in Newtons (N). All measurements were performed three times.

[0129] The cutting speed was set to 50 ram/min, and the cutting distance was 40 mm. The results are shown in FIG. 4a.

[0130] It can be seen that the inventive product according to Example 1 has a higher strength compared to the product of Comparative Example 2 in both directions of the cut (F.sub.T and F.sub.L).

[0131] FIG. 4b shows the anisotropy index for both samples, which index can be calculated from the ratio of the F.sub.T and F.sub.L values (A=F.sub.T/F.sub.L) and represents a measure of the fibrousness of the product. The value for the inventive product according to Example 1 is significantly reduced compared to the value for the product of Comparative Example 2, which suggests an increased fibrousness of the inventive product according to Example 1.

[0132] The anisotropic index for meat products like chicken or beef were close to 1, ranging from 1.1-1.75, but for fish the anisotropic index was 4.95, indicating the high variation in the longitudinal and transverse texture of the fish.

[0133] Bread dough does not have any pronounced anisotropy with respect to the F.sub.T and F.sub.L values.

[0134] The texture profile for meat analogues was compared with extruded foamed snack product, and the difference in the texture was confirmed by the fluctuating texture profile of the snack product, ‘knusperbrot’ (FIG. 5a), compared to the smoother texture profile of the meat substitute (FIG. 5b). This is due to the fundamental difference in the texture of a ‘knusperbrot’ which is crunchy and thereby have multiple force peaks as the blade penetrates the sample.

EXAMPLE 3

[0135] In a 42 mm twin screw extruder from Bühler with an additional gas supply unit, the following raw material was processed at temperatures up to 152° C. and screw speed of 400 rpm:

TABLE-US-00006 Pea protein isolate 43.2% Pea fiber 8.8% Water 47.5% Oil 0.5%

[0136] The gas injection rate into the extruders were kept at the rate of 0 g/h, 35 g/h, 52 g/h and 70 g/h in four different trials. The total throughput at the outlet of the cooling die was 35 Kg/h.

Texture

(a) Analysis of Meat Substitutes

[0137] Texture analysis was carried out on the samples produced as per example 3. FIG. 5 represents the comparison of samples produced with 3 levels of gas injection rate. The maximum force (peak force) which is required to cut through the structure of the products in example 3 was determined using a Warner Bratzler Blade Set with a thickness of 1 mm. This analysis helps to quantify the cutting or biting property of the product. All texture analysis measurements were made at room temperature of 25° C.

[0138] The extruded samples produced according to example 3 were cut into square pieces of 20 mm×20 mm as part of sample preparation for the texture analysis. The samples were then cut transversally (right-angled to the flow direction of the extruded strand (F.sub.T) as well as cut parallel to the flow direction of the extruded strand (F.sub.L), and the respective maximum force (peak force) was determined and expressed in MPa. For each cut direction, 6 replicates were taken. The results are shown in FIG. 6.

[0139] The ratio of cutting force in both directions was calculated and expressed as Anisotropic index (A=F.sub.T/F.sub.L). The A value for the foamed product with gas injection rate higher than 0 g/h lied between 1.1.-1.5, whereas this value for the non-foamed product was closer to 1.

(b) Analysis of Meat Products

[0140] For comparison purposes, the texture analysis was carried out for chicken, beef and fish products available in the market using a Warner Blatzer blade with ‘Rectangular’ slot blade (HDP/WBR) and thickness 1.016 mm. The cutting speed of the Warner-Bratzler blade was set to 1 mm/sec, and the blade was penetrated through the sample. The samples were measured at 25° C. A total of 3 replicates was measured for each sample.

[0141] It was found that the average of the maximum force for these meat and fish products ranged from 45.0 to 175.1 N in the transverse direction and from 10.0 to 99.9 N in the longitudinal direction.

[0142] The anisotropic index for meat products like chicken or beef were close to 1 ranging from 1.1-1.75 but for fish the anisotropic index was 4.95, indicating the high variation in the longitudinal and transverse texture of the fish.

[0143] The texture profile for meat analogues was compared with extruded foamed snack product and the difference in the texture was confirmed by the fluctuating texture profile of the snack product, ‘knusperbrot’ (FIG. 7a), compared to the smoother texture profile of the meat substitute (FIG. 7b). This is due to the fundamental difference in the texture of a ‘knusperbrot’ which is crunchy and thereby have multiple force peaks as the blade penetrates the sample.

[0144] In FIGS. 8a and b, microscopic images of the porosity of a product produced according to example 3 are shown. The light microscopy (20×) image for the foamed product in example 3 with gas injection rate of 70 g/h shows the presence of interconnected pores inside the foamed product.