Double-crosslinking type foam template method oil gel and preparation method thereof

Abstract

The invention discloses a foam template method oil gel prepared through bi-crosslinking and a preparation method thereof, and belongs to the technical field of fat substitute preparation. Soybean protein isolate, k-carrageenan and glyceryl monostearate are used as raw materials, a soybean protein isolate-k-carrageenan composite solution is formed through a physical crosslinking method, stable water-based foam is formed after high-speed homogenization, then the foam is subjected to vacuum freeze drying to form porous aerogel, and the porous aerogel is prepared. And then soaking in a glyceryl monostearate oil solution for full absorption, and standing at room temperature to obtain the bi-crosslinking foam template method oil gel. The oleogel disclosed by the invention not only has relatively strong oil holding capacity, but also has relatively high mechanical property and oxidation resistance, can simulate the temperature sensitivity of traditional fat, and can partially or completely replace solid fat to be applied to food.

Description

Technical Field

[0001] The invention belongs to the technical field of fat substitute preparation, and in particular relates to a double-crosslinked foam template oil gel and a preparation method thereof. Background Art

[0002] Solid fats are important ingredients in baked goods, margarine, and puff pastry, responsible for providing specific mechanical strength and unique flavor. However, solid fats contain trans fatty acids and saturated fatty acids, and long-term consumption may increase the risk of coronary heart disease, atherosclerosis, and hyperglycemia. Therefore, oil gelation has attracted attention as a green and healthy structured oil technology.

[0003] The preparation of oil gel can be divided into direct method and indirect method. The direct method is to add lipophilic oil gelling agent to the oil and structure the oil by heating or chemical modification. However, the direct method requires too high a concentration of gelling agent, and the constructed oil gel has an undesirable waxy taste, which greatly limits its application in food. The indirect method uses an intermediate template medium to construct oil, such as emulsions, aerogels, and foams. Among them, the foam template method can avoid problems such as organic solvent residues and quality degradation of the finished product due to high-speed shearing, so it has received more attention. However, since the gelling agent of the foam template oil gel is usually food-grade polymers such as proteins and polysaccharides, the constructed oil gel usually has disadvantages such as oil leakage and poor mechanical strength, and cannot simulate the temperature sensitivity of traditional fats.

[0004] The present invention utilizes double cross-linking technology to prepare foam template method oil gel. Specifically, the gel network formed by electrostatic interaction between soy protein isolate and k-carrageenan is used as physical cross-linking, and the crystal network formed by glyceryl monostearate in oil is used as chemical cross-linking. The oil holding capacity and physical properties of the oil gel are improved through the synergy of the double networks, and the oil gel is closer to the characteristics of fat, so as to be better applied to food. Summary of the invention

[0005] The purpose of the present invention is to provide a double cross-linked foam template oil gel and a preparation method thereof, aiming to provide an oil gel with high oil retention, high mechanical strength and high oxidation stability.

[0006] The present invention also provides a method for preparing the double cross-linked foam template oil gel as described above, comprising the following steps:

[0007] S1, preparing a composite solution using soy protein isolate and k-carrageenan as raw materials, homogenizing the composite solution at high speed to prepare an aqueous foam, and then performing vacuum freeze drying to obtain a porous aerogel;

[0008] S2, dissolving glyceryl monostearate in the heated vegetable oil, mixing evenly, to obtain an oil solution;

[0009] S3, immersing the aerogel of S1 in the oil solution of S2, and taking it out after absorbing the oil to obtain the double cross-linked foam template method oil gel.

[0010] Optionally, in step S1, the mass ratio of soy protein isolate to k-carrageenan is 2:0.4 to 2:0.7.

[0011] Optionally, in step S1, the pH of the composite solution is 2-9.

[0012] Optionally, in step S2, the amount of glyceryl monostearate added is 3-12%.

[0013] Optionally, in step S2, the heating temperature is 70-90°C.

[0014] Optionally, in step S3, the soaking time is 3 to 10 minutes.

[0015] The effective effects of the present invention are:

[0016] S1. In the technical solution provided by the present invention, the foam stability of soy protein isolate is improved by adding k-carrageenan, and a soy protein isolate-k-carrageenan composite aerogel is prepared, thereby solving the problems of loose structure and large pore size of single protein-based aerogel and significantly improving the oil holding capacity of aerogel;

[0017] S2. The double-crosslinked foam template oil gel prepared by the present invention has a dense three-dimensional network structure, which greatly improves the mechanical strength and oxidative stability of the oil gel and can better simulate the properties of fat;

[0018] S3. The double-crosslinked foam template oil gel prepared by the present invention can also be used as an ideal carrier for loading fat-soluble functional factors, providing a new direction for the application in the field of functional factor delivery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0020] Figure 1 1 is a scanning electron microscope image of the aerogel in Examples 1 to 4 of the present invention.

[0021] Figure 2 It is the oil absorption and oil holding capacity of the aerogel in Examples 1 to 4 of the present invention.

[0022] Figure 3 It is the yield strength of the oil gel in Examples 3, 5-7 of the present invention and Comparative Example 1.

[0023] Figure 4 The peroxide value variation diagram of the oil gel in Examples 3, 5-7 of the present invention and Comparative Example 1 is shown. DETAILED DESCRIPTION

[0024] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explaining the present invention and are not intended to limit the present invention.

[0025] The experimental methods used in the present invention are all conventional methods unless otherwise specified; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0026] Example 1

[0027] S1. Accurately weigh soy protein isolate, dissolve in 100 mL deionized water, adjust the pH to 7, and mix with k-carrageenan solution in equal volumes to make the final protein concentration 2% (w / v), k-carrageenan concentration 0.4% (w / v), and adjust the pH to 7 again. Use a high-speed homogenizer at a rate of 10,000 rpm for 4 min to obtain water foam;

[0028] S2, the water foam of S1 was transferred to a -20°C refrigerator and frozen for 24 h, and then freeze-dried at -68°C for 24 h to obtain a porous aerogel;

[0029] S3. Accurately weigh glyceryl monostearate, dissolve it in 100 mL of soybean oil heated to 80°C to a concentration of 3% (w / v), and stir for 20 min to dissolve it to obtain an oil solution;

[0030] S4. Place the porous aerogel of S2 in the oil solution described in S3 to absorb oil for 10 min, take it out and suspend it for 1 min, wipe off the oil leaked on the surface and cool it at room temperature for 30 min to obtain a double-crosslinked foam template oil gel.

[0031] Example 2

[0032] The preparation method is the same as that in Example 1, except that the concentration of kappa carrageenan in step S1 is 0.5% (w / v).

[0033] Example 3

[0034] The preparation method is the same as that of Example 1, except that the concentration of k-carrageenan in step S1 is 0.6% (w / v).

[0035] Example 4

[0036] The preparation method is the same as that in Example 1, except that the concentration of k-carrageenan in step S1 is 0.7% (w / v).

[0037] Example 5

[0038] The preparation method is the same as that of Example 3, except that the concentration of glyceryl monostearate in step S3 is 6% (w / v).

[0039] Example 6

[0040] The preparation method is the same as that of Example 3, except that the concentration of glyceryl monostearate in step S3 is 9% (w / v).

[0041] Example 7

[0042] The preparation method is the same as that of Example 3, except that the concentration of glyceryl monostearate in step S3 is 12% (w / v).

[0043] Comparative Example 1

[0044] The preparation method is the same as that of Example 3, except that the concentration of glyceryl monostearate in step S3 is 0% (w / v).

[0045] Experimental Example 1 Microstructure Experiment

[0046] The aerogels prepared in Example 1, Example 2, Example 3, and Example 4 were used as experimental samples, and the microscopic network structure of the aerogels was observed by scanning electron microscopy.

[0047] pass Figure 1 The experimental results show that the pores in the aerogel prepared in Example 1 are of different sizes and unevenly distributed. As the concentration of k-carrageenan increases, the aerogel has a honeycomb network structure, but when the concentration is too high, the honeycomb structure will transform into a sheet structure.

[0048] Experimental Example 2 Oil absorption and oil holding capacity experiments

[0049] The aerogels prepared in Example 1, Example 2, Example 3, and Example 4 were used as experimental samples. The aerogels were weighed and immersed in soybean oil. The weight of the oil gel was weighed every 10 minutes within 2 hours until it reached a constant weight. The oil absorption capacity of the aerogel was calculated as follows:

[0050] Oil absorption capacity (g / g) = weight of aerogel after oil absorption / weight of aerogel before oil absorption

[0051] The oil gel was centrifuged at 8000 rpm for 15 min. Excess oil was removed and weighed. The oil holding capacity was calculated as follows:

[0052] Oil holding capacity (%) = initial weight of oil gel * 100 / weight of oil gel after centrifugation

[0053] pass Figure 2It can be seen from the experimental results that with the increase in the amount of k-carrageenan added, the oil absorption of the aerogel decreased, but the oil holding rate was greatly improved, among which Example 3 had the best oil holding rate, up to 94%.

[0054] Experimental Example 3 Mechanical Strength of Oil Gel

[0055] Texture analysis was performed using a cylindrical probe with a diameter of 36 mm. The oil gels of Comparative Example 1, Examples 3, and 5 to 7 were subjected to compression tests using the full texture analysis mode, with a rate of 2.0 mm / s before the test, 1.0 mm / s during the test, 2.0 mm / s after the test, a trigger force of 5.0 g, and a compression degree set to 80%.

[0056] pass Figure 3 From the experimental results, it can be seen that the addition of glyceryl monostearate enhances the yield strength of the oil gel, indicating that the formation of the double cross-linking system enhances the texture properties of the oil gel.

[0057] Experimental Example 4 Determination of Oxidative Stability of Oil Gel

[0058] The oil gels of Comparative Example 1 and Examples 3 and 5 to 7 were used as samples, and the peroxide values ​​were measured during accelerated oxidation storage at 50° C. for 18 days to detect the oxidative stability of the oil gels.

[0059] pass Figure 4 It can be seen from the experimental results that the oil gel prepared by the present invention has good oxidative stability and can still maintain good stability in an accelerated oxidation environment, especially the double cross-linked oil gel. Compared with the oil gel without adding glyceryl monostearate, the double network formed after adding it more effectively hinders the contact between oil and oxygen, thereby delaying the oxidation of oil.

Claims

1. A double cross-linked foam template oil gel, characterized in that: The double cross-linking is physical and chemical double cross-linking, with the gel network formed by electrostatic interaction between soy protein isolate and k-carrageenan as the physical cross-linking, and the crystal network formed by glyceryl monostearate in oil as the chemical cross-linking.

2. A method for preparing a double cross-linked foam template oil gel, characterized in that: The following steps are involved: S1, preparing a composite solution using soy protein isolate and k-carrageenan as raw materials, homogenizing the composite solution at high speed to prepare an aqueous foam, and then performing vacuum freeze drying to obtain a porous aerogel; S2, dissolving glyceryl monostearate in the heated soybean oil, mixing evenly, to obtain an oil solution; S3, immersing the aerogel of S1 in the oil solution of S2, and taking it out after absorbing the oil to obtain the double cross-linked foam template method oil gel.

3. The method for preparing a double cross-linked foam template oil gel according to claim 2, characterized in that: In S1, the mass ratio of the soy protein isolate to k-carrageenan is 2:0.4-2:0.

7.

4. The method for preparing a double cross-linked foam template oil gel according to claim 2, characterized in that: In S1, the pH of the composite solution is 2-9.

5. The method for preparing a double cross-linked foam template oil gel according to claim 2, characterized in that: In S1, the specific steps of S1 are: high-speed shearing the composite solution of soy protein isolate and k-carrageenan at 10,000 rpm for 4 min, then freezing it at -20°C for 24 h, and finally freeze-drying it at -68°C for 24 h to obtain a porous aerogel.

6. The method for preparing a double cross-linked foam template oil gel according to claim 2, characterized in that: In S2, the amount of glyceryl monostearate added is 3-12%.

7. The method for preparing a double cross-linked foam template oil gel according to claim 2, characterized in that: In S2, the temperature of the heated soybean oil is 70-90°C.

8. The method for preparing a double cross-linked foam template oil gel according to claim 2, characterized in that: In S3, the soaking time is 3 to 10 min.

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