Carrageenan- and soy protein isolate-based meal replacement food, and preparation method therefor

Abstract

Disclosed are a carrageenan- and soy protein isolate-based meal replacement food, and a preparation method therefor. The meal replacement food is formed by an aqueous solution of soy protein isolate, λ-carrageenan and ι-carrageenan under induction in acidic conditions. A meal replacement gel comprises the following raw materials in percentage by mass: 5% of soy protein isolate, 0.25%-0.75% of λ-carrageenan, 0.25%-1% of ι-carrageenan, with the balance being water; the pH value in said acidic conditions is 1-2. The preparation method comprises the following steps: adding soy protein isolate, λ-carrageenan and ι-carrageenan to pure water, and heating, stirring and dissolving same to obtain a mixed solution; and cooling the mixed solution to room temperature, loading same into a dialysis bag, and immersing same in an acidic solution to obtain the gel, the acidic solution being a hydrochloric acid solution.

Description

Meal replacement foods based on carrageenan and soy protein isolate and their preparation methods Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to meal replacement foods based on carrageenan and soy protein isolate and their preparation methods. Background Technology

[0002] Over the past 40 years, the number of obese people worldwide has surged. The "Report on Nutrition and Chronic Diseases of Chinese Residents (2020)" released by the State Council Information Office indicates that over 50% of adult residents in my country are overweight or obese, totaling approximately 500 million people. Overweight and obesity can lead to cardiovascular disease; similarly, the weight of obese individuals places a heavy burden on the body, causing joint pain or mobility impairments; overweight and obesity can also cause sleep apnea syndrome, endocrine and metabolic disorders, gallbladder disease, and fatty liver disease.

[0003] Mixtures of proteins and highly electronegative biopolymers can form gastric gels at low polysaccharide concentrations, producing a feeling of fullness, reducing food intake, slowing down digestion, and effectively helping to control weight. Soy protein isolate (SPI) is a protein powder with good nutritional value and functional properties, made from low-temperature defatted soybean meal through extraction and separation processes to remove non-protein components. It is one of the most satiating macronutrients and can be used for weight management and obesity control. Carrageenan, also known as salicornic acid, is a calcium, potassium, sodium, and ammonium salt of a polysaccharide sulfate ester composed of galactose and dehydrated galactose, commonly used as a gelling agent in food. Carrageenan, as a dietary fiber, has a satiating effect without providing additional energy. When combined with soy protein isolate, it can form a gel at a pH far below the isoelectric point of proteins, making it suitable for use as a weight-loss meal replacement. However, pure soy protein isolate / carrageenan gels have disadvantages such as low mechanical strength, rapid degradation, poor water-holding capacity, and short duration of satiety. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a weight-loss meal replacement food composed of carrageenan and soy protein isolate, which has high strength, strong water-holding capacity, and long-lasting satiety, as well as a method for its preparation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a meal replacement product based on carrageenan and soy protein isolate, comprising, by weight fraction:

[0007] The composition consists of 5% soy protein isolate, 0.25%–0.75% λ-carrageenan, 0.25%–1% ι-carrageenan, and the remainder is water.

[0008] Secondly, the present invention provides a method for preparing the meal replacement product provided in the first aspect, comprising the following steps:

[0009] Soy protein isolate, λ-carrageenan, and ι-carrageenan are added to pure water, heated and stirred until dissolved, and then cooled to obtain the final product.

[0010] Thirdly, the present invention provides a meal replacement gel based on carrageenan and soy protein isolate, which is formed by aqueous solutions of soy protein isolate, λ-carrageenan, and ι-carrageenan under acidic conditions.

[0011] Fourthly, the present invention provides a method for preparing the meal replacement gel provided in the third aspect, comprising the following steps:

[0012] Soy protein isolate, λ-carrageenan, and ι-carrageenan were added to pure water, heated and stirred to dissolve, and a mixed solution was obtained.

[0013] After cooling the mixed solution to room temperature, it was placed in a dialysis bag and immersed in an acidic solution to obtain the gel.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] (1) This invention utilizes soy protein isolate to form a hydrogel with λ-carrageenan and ι-carrageenan under acid induction to prepare meal replacement food. Electrostatic interaction occurs between the protein and the anionic polysaccharide to form a gel with a network structure. λ-carrageenan and ι-carrageenan have high electronegativity. Their synergistic effect enhances the stability of the network structure, improves the gel strength and water holding capacity, prolongs the gastric emptying time of the hydrogel, and effectively prolongs the duration of satiety.

[0016] (2) The hydrogel prepared by the present invention has good biocompatibility and safety, and meets the requirements of food grade. After the composite solution of soy protein isolate with λ-carrageenan and ι-carrageenan enters the stomach, it quickly forms a gel and forms a gel film on the surface. Most of the protein is wrapped inside the gel. Digestion in the stomach starts from the outside of the gel and proceeds slowly, only providing a feeling of fullness. The rich soy protein isolate can provide a relatively good source of nutrition and reduce weight by reducing calorie intake, without causing adverse effects on the human body.

[0017] (3) The preparation method of the present invention has a simple process and is easy to mass-produce in industry. Attached Figure Description

[0018] Figure 1 is a laser confocal micrograph of the hydrogel prepared in Example 1;

[0019] Figure 2 shows the low-field nuclear magnetic resonance spectrum of the hydrogel prepared in Example 1. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; unless specifically specified, the technical means used are all conventional means well known to those skilled in the art.

[0021] The meal replacement beverage based on carrageenan and soy protein isolate provided in this embodiment of the invention comprises, by weight fraction:

[0022] The composition consists of 5% soy protein isolate, 0.25%–0.75% λ-carrageenan, 0.25%–1% ι-carrageenan, and the remainder is water.

[0023] When a meal replacement product enters the stomach, under the induction of gastric acid, the protein and carrageenan can quickly form a gel with a network structure through electrostatic interaction. λ-carrageenan and ι-carrageenan have high electronegativity, and their synergistic effect can make the network structure more stable, with high gel strength and strong water retention capacity.

[0024] The method for preparing a meal replacement drink based on carrageenan and soy protein isolate provided in this invention includes the following steps:

[0025] Soy protein isolate, λ-carrageenan, and ι-carrageenan are added to pure water, heated and stirred until dissolved, and then cooled to obtain the final product.

[0026] In some preferred embodiments, the heating temperature is 90–98°C.

[0027] The meal replacement gel based on carrageenan and soy protein isolate provided in this embodiment of the invention is formed by aqueous solutions of soy protein isolate, λ-carrageenan, and ι-carrageenan under acidic conditions.

[0028] In some preferred embodiments, the raw material composition of the meal replacement gel, by mass fraction, includes:

[0029] The composition consists of 5% soy protein isolate, 0.25%–0.75% λ-carrageenan, 0.25%–1% ι-carrageenan, and the remainder is water.

[0030] In some preferred embodiments, the pH of the acidic conditions is 1 to 2.

[0031] The method for preparing a meal replacement gel based on carrageenan and soy protein isolate provided in this invention includes the following steps:

[0032] Soy protein isolate, λ-carrageenan, and ι-carrageenan were added to pure water, heated and stirred to dissolve, and a mixed solution was obtained.

[0033] After cooling the mixed solution to room temperature, it was placed in a dialysis bag and immersed in an acidic solution to obtain the gel.

[0034] In some preferred embodiments, the acidic solution is a hydrochloric acid solution.

[0035] In some preferred embodiments, the pH of the acidic solution is 1 to 2.

[0036] Comparative Example 1

[0037] This comparative example provides five groups of meal replacement gels composed of soy protein isolate and different amounts of λ-carrageenan, prepared as follows:

[0038] λ-carrageenan and SPI powder were added to a flask containing a certain amount of ultrapure water, and then stirred at 750 rpm for 1.5 h at 95 °C to obtain an SP1 / λC mixed solution. After cooling to room temperature, the solution was placed in a dialysis bag and soaked in hydrochloric acid solution with a pH of 1.2 for 24 h to form an SP1 / λC gel.

[0039] Each group of SP1 / λC gels was removed, cut, and subjected to performance testing. The raw material composition and performance test results of each group are shown in Table 1.

[0040] Table 1

[0041] The maximum hardness of the hydrogel obtained in this comparative example is 0.5N for group D3. This is because λ-carrageenan has a high charge density, and the electrostatic interaction becomes stronger at higher concentrations. However, the high gelation rate and system viscosity during the gelation process can lead to the formation of a hollow structure in the gel, affecting the gel properties and causing a decrease in gel hardness.

[0042] Example 1

[0043] This embodiment provides seven groups of meal replacement gels composed of soy protein isolate, λ-carrageenan, and different amounts of ι-carrageenan, prepared by the following methods:

[0044] SPI powder, λ-carrageenan, and ι-carrageenan were added to a flask containing a certain amount of ultrapure water and stirred at 750 rpm for 1.5 h at 95 °C to obtain a mixed solution of SP1 / λC / ιC. After cooling to room temperature, the solution was placed in a dialysis bag and soaked in hydrochloric acid solution with a pH of 1.2 for 24 h to form an SP1 / λC / ιC gel.

[0045] Each group of SPI / λC / ιC gels was removed, cut, and subjected to performance testing. The raw material composition and performance test results of each group are shown in Table 2.

[0046] Table 2

[0047] Figure 1 shows micrographs of acid-induced SPI / λC / ιC gels at different ι-carrageenan concentrations, taken using laser confocal microscopy. In the figures, the bright red areas represent the protein network stained with Rhodamine B, while the black areas represent the protein-deficient serum phase. With increasing ι-carrageenan content (>0.25%, w / w), the SPI / λC / ιC gel stiffness increases, and the gel structure improves. At an ι-carrageenan content of 0.55%, the network structure is most uniform and dense, and the gel stiffness is greatest. Further increasing the ι-carrageenan content decreases the gel stiffness. The laser confocal microscopy images show a phase-separated structure; the polysaccharide concentration determines the degree of phase separation and whether the protein and polysaccharide form a continuous network. At lower ι-carrageenan concentrations, the interaction between λ-carrageenan and protein dominates. At this point, protein particles and λ-carrageenan form a gel framework through electrostatic interactions, creating a continuous phase. At an ι-carrageenan concentration of 0.55% (w / w), the two different types of carrageenan form a bicontinuous gel network structure, which is the most stable. As the concentration of ι-carrageenan is further increased, ι-carrageenan becomes dominant, the continuity of the protein phase disappears, and the gel network transforms into a continuous phase structure dominated by ι-carrageenan. In this type of network, SPI is embedded in the continuous carrageenan phase as irregular aggregates. The blending of the two carrageenans can effectively prevent flocculation by enhancing electrostatic repulsion and reducing hydrophobic interactions. The combination of carrageenans facilitates the formation and development of cross-linked networks through intermolecular association between polysaccharide chains, thereby hindering bridging flocculation caused by strong electrostatic interactions between carrageenan and protein micelles.

[0048] The proportion and distribution of water in different states in an acid-induced SP1 / λC / ιC gel system were investigated using low-frequency nuclear magnetic resonance (LF-NMR) by measuring the T2 relaxation time. Typically, fitting and inversion of the LF-NMR spectra yielded three distinct T2 distribution peaks, corresponding to three different water states: tightly bound water (1–10 ms, P21), weakly bound water (10–600 ms, P22), and free water (>600 ms, P23). The LF-NMR spectra of the acid-induced SP1 / λC / ιC gel are shown in Figure 2. It can be seen that weakly bound water (>97%) dominates in the acid-induced SP1 / λC / ιC gel. With increasing ι-carrageenan content, weakly bound water gradually increases, while tightly bound water and free water slightly decrease. The results showed that with the addition of ι-carrageenan (0.25%), the gel exhibited a wider shoulder at the P22 peak (10-600 ms), indicating an increase in the degrees of freedom of water molecules. Further addition of ι-carrageenan resulted in a gradually narrowing shoulder, suggesting enhanced interaction between the gel and water, likely due to the hydrophilicity of carrageenan.

[0049] In summary, this embodiment increases the crosslinking density and structural rigidity through the synergistic effect of λ-carrageenan and ι-carrageenan, thereby improving the hardness of the hydrogel, prolonging the digestion time, and enhancing the feeling of fullness.

[0050] Example 2

[0051] This embodiment provides three groups of meal replacement gels composed of soy protein isolate and different amounts of λ-carrageenan and ι-carrageenan, prepared by the following methods:

[0052] SPI powder, λ-carrageenan, and ι-carrageenan were added to a flask containing a certain amount of ultrapure water and stirred at 750 rpm for 1.5 h at 95 °C to obtain a mixed solution of SP1 / λC / ιC. After cooling to room temperature, the solution was placed in a dialysis bag and soaked in hydrochloric acid solution with pH 2 for 24 h to form SP1 / λC / ιC gel.

[0053] Each group of SPI / λC / ιC gels was removed, cut, and subjected to performance testing. The raw material composition and performance test results of each group are shown in Table 3.

[0054] Table 3

[0055] Comparative Example 2

[0056] In this comparative example, ι-carrageenan was replaced with κ-carrageenan to prepare a gel composed of soy protein isolate, λ-carrageenan, and different amounts of κ-carrageenan. The preparation method is as follows:

[0057] SPI powder, λ-carrageenan, and κ-carrageenan were added to a flask containing a certain amount of ultrapure water, and then stirred at 750 rpm for 1.5 h at 95 °C to obtain a mixed solution of SP1 / λC / κC, which formed a gel upon cooling.

[0058] The SPI / λC / κC gels from each group were removed, cut, and subjected to performance testing. The raw material composition and performance test results of each group are shown in Table 4.

[0059] Table 4

[0060] This comparative example can form a gel without acid induction, but it is harder, inconvenient to swallow, and has a poor taste.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A meal replacement gel based on carrageenan and soy protein isolate, characterized in that, A water solution of soybean protein isolate, lambda carrageenan and iota carrageenan is induced to form a gel under acidic conditions; The raw material composition of the meal replacement gel comprises, by mass fraction: 5% soybean protein isolate, 0.25%-0.75% lambda carrageenan, 0.25%-1% iota carrageenan, and the balance being water; The pH of the acidic conditions is 1-2.

2. The process for the preparation of a carrageenan and soy protein isolate based meal replacement gel according to claim 1, characterized in that, The method comprises the following steps: Soybean protein isolate, lambda carrageenan and iota carrageenan are added to pure water, heated and stirred to dissolve, to obtain a mixed solution; After the mixed solution is cooled to room temperature, it is loaded into a dialysis bag and soaked in an acidic solution to obtain the gel.

3. The process for the preparation of a carrageenan and soy protein isolate based meal replacement gel according to claim 2, characterized in that, The acidic solution is a hydrochloric acid solution.

4. The process for the preparation of a carrageenan and soy protein isolate based meal replacement gel according to claim 2, characterized in that, The pH of the acidic solution is 1-2.

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