A method for rapid detection of water-soluble protein peptide content

Abstract

The present invention relates to the field of rapid food detection, and in particular to a method for rapid detection of water-soluble protein peptide content, comprising the following steps: step 1: determining the refractive index of a sample with known water-soluble protein peptide content, and establishing a standard curve of refractive index-water-soluble protein peptide content; step 2: detecting the refractive index of a substance to be tested; step 3: bringing the refractive index into the standard curve obtained in step 1 to obtain the water-soluble protein peptide content in the substance to be tested. The method for rapid detection of water-soluble protein peptides provided by the present invention uses a refractometer to obtain a correlation with the water-soluble protein peptide content, is simple to operate, and has a short waiting time of only 10s-5min to obtain a result, providing support for rapidly obtaining the water-soluble protein peptide content during workshop production and protein hydrolysis experiments.

Description

Technical Field

[0001] The invention relates to the field of rapid food detection, and in particular to a method for rapid detection of water-soluble protein peptide content. Background Art

[0002] Plant protein is not easily digested and absorbed after ingestion due to its large molecular weight and complex structure, which affects the effective performance of its physiological functions and nutritional value. After protein hydrolysis, water-soluble protein peptides and free amino acids are formed. Water-soluble protein peptides have a simple structure, small molecular weight and multiple physiological functions.

[0003] At present, the methods for determining the degree of protein hydrolysis used in plant protein beverages mainly include: ninhydrin method and protein hydrolysis degree (DH) determination method. The ninhydrin method uses the hydrolyzate of the protein sample to be tested as a standard sample for ninhydrin colorimetry to determine the degree of protein hydrolysis. When operating this method, it is necessary to draw a standard curve, determine the -NH2 group in the hydrolyzed protein solution, determine the protein content in the hydrolyzed protein, and finally calculate the results. The steps of this method are cumbersome, many reagents are used, and a standard curve needs to be drawn for each test. The operation is complicated and the results cannot be quickly obtained. Protein hydrolysis degree (DH) determination method-OPA (o-phthalaldehyde) method, the OPA method defines that the degree of hydrolysis refers to the percentage of hydrolyzed peptide bonds in the protein to the total peptide bonds. The principle is that OPA will form a yellow compound with free α-amino in the presence of β-hydroxyethanol, which has a characteristic absorption at 340nm, and its OD (optical density) value can be detected by a spectrophotometer. During the operation, the standard solution, blank and sample need to be tested separately, and then calculated according to the test results. This method requires multiple reagents. In actual testing, this method has the problem of long testing process and multiple reagents. It cannot solve the need to quickly obtain the content of water-soluble protein peptides during experimental operation or workshop process optimization, and is not suitable for the testing of experimental samples and enterprise samples.

[0004] Refractometers are used to measure the concentration of soluble solids, especially sugars, but are not used to measure the content of water-soluble protein peptides. Summary of the invention

[0005] Therefore, in order to overcome the long time consumption of water-soluble protein peptide content detection in the prior art, the present invention cannot adapt to the defects of needing to quickly obtain water-soluble protein peptide content during experiments and enterprise production, thereby providing a method for quickly detecting water-soluble protein peptide content, water-soluble protein peptide and free amino acids are formed after protein hydrolysis, and macromolecular protein will form solid deposition in the lower layer after centrifugation, and water-soluble protein peptide and free amino acids are in the supernatant. In the present invention, it is stipulated that: the degree of hydrolysis is the ratio between water-soluble protein peptide and total protein, and the present invention pioneeringly uses the value read by the refractometer to correspond to the water-soluble protein peptide content, so that the two are associated. A standard curve was established in the early stage, and in the specific operation, the refractive index of the supernatant was measured by the refractometer through the corresponding standard curve, so that the water-soluble protein peptide content can be quickly obtained, which provides convenience for workshop production.

[0006] A method for rapidly detecting the content of water-soluble protein peptides comprises the following steps:

[0007] Step 1: Determine the refractive index of a sample with a known water-soluble protein peptide content and establish a standard curve of refractive index-water-soluble protein peptide content;

[0008] Step 2: Detect the refractive index of the substance to be tested;

[0009] Step 3: Substitute the refractive index into the standard curve obtained in step 1 to obtain the water-soluble protein peptide content in the substance to be tested.

[0010] On the basis of the above scheme, step 1 specifically includes: weighing and crushing the plant protein raw material, adding water to the crushed material to obtain a mixed solution, heating the mixed solution, adding different amounts of enzymes for hydrolysis reaction, centrifuging to obtain the supernatant, measuring the refractive index, using the Kjeldahl method to detect the water-soluble protein peptide content, and establishing a standard curve of refractive index-water-soluble protein peptide content based on the corresponding relationship.

[0011] On the basis of the above scheme, the plant protein raw materials are crushed by a colloid mill under anhydrous conditions.

[0012] Based on the above scheme, the mass ratio of the plant protein raw material to water is 1:2 to 1:10.

[0013] Based on the above scheme, the heating temperature is 30°C to 80°C, preferably, the heating temperature is 50°C to 60°C.

[0014] On the basis of the above scheme, the enzyme includes one or more of papain, alkaline protease, bacterial protease, and trypsin;

[0015] Based on the above scheme, the amount of enzyme added is 0.02% to 10% of the mass of the plant protein raw material based on the mass of the plant protein raw material;

[0016] And / or, the hydrolysis reaction time is 2h to 6h.

[0017] Based on the above scheme, the centrifugal conditions are: 6000r / min~10000r / min, centrifugation 5min~15min.

[0018] Based on the above scheme, the plant protein raw materials include: walnuts and / or soybeans.

[0019] The application of the above method for rapid detection of water-soluble protein peptide content in determining the degree of protein hydrolysis also falls within the protection scope of the present invention.

[0020] The technical solution of the present invention has the following advantages:

[0021] The method for quickly detecting the content of water-soluble protein peptides provided by the present invention only needs to establish a standard curve of refractive index-water-soluble protein peptide content according to the corresponding relationship between the refractive index of the water-soluble solid concentration of the supernatant and the corresponding water-soluble protein peptide content during the early preparation. During production in an enterprise, it is not necessary to measure the content of the water-soluble protein peptides. It is only necessary to centrifuge the product of the hydrolysis reaction, measure the refractive index of the supernatant using a refractometer, and obtain the relative water-soluble protein peptide content according to the standard curve. The present invention uses the refractive index obtained by the refractometer to correlate with the water-soluble protein peptide content, has simple operation, short waiting time, and can obtain the result in only 10 seconds to 5 minutes, thereby providing support for quickly obtaining the content of water-soluble protein peptides during workshop production and protein hydrolysis experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 is the standard curve of Example 1 of the present invention;

[0024] Figure 2 is the standard curve of Example 2 of the present invention;

[0025] Figure 3 is the standard curve of Example 3 of the present invention;

[0026] Figure 4 It is the standard curve of Example 4 of the present invention. DETAILED DESCRIPTION

[0027] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0028] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0029] The alkaline protease used in the embodiment of the present invention was purchased from Danisco, papain was purchased from AB Enzyme Preparation Company of Germany or Novozymes, with an enzyme activity of 800,000, bacterial protease was purchased from AB Enzyme Preparation Company of Germany, and trypsin was purchased from Novozymes.

[0030] Example 1

[0031] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.02% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "Determination of Protein in Foods GB 50095-2010", and measure the refractive index with a refractometer;

[0032] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.05% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0033] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.5% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0034] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 1% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0035] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 2% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0036] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 4% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0037] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 6% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0038] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 8% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0039] Weigh 80 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50°C, add 10% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer.

[0040] Table 1 Relationship between refractive index and water-soluble protein peptide content

[0041]

[0042]

[0043] According to the data in Table 1, a standard curve was drawn with the water-soluble protein peptide content of the supernatant as the abscissa and the refractive index of the supernatant as the ordinate, and the standard curve y=1.6903x+0.05, R2=0.9978 was obtained.

[0044] Weigh 80g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800g to obtain a mixed solution, heat to 40°C, add 3% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 5000r / min, take the supernatant, measure the refractive index with a refractometer, and obtain: 1.41, substituting 1.41 into the standard curve y=1.6903X+0.05, R2=0.9978, and obtaining the corresponding water-soluble protein peptide content of 0.8046g / 100mL;

[0045] Weigh 80g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800g to obtain a mixed solution, heat to 60°C, add 3.5% alkaline protease based on the mass of the walnut kernels, react for 2 hours, centrifuge at 5000r / min, take the supernatant, and measure the refractive index with a refractometer to obtain: 1.69, substitute 1.69 into the standard curve y=1.6903X+0.05, R2=0.9978, and obtain the corresponding water-soluble protein peptide content of 0.9702 / 100mL.

[0046] Verification: The water-soluble protein peptide contents were measured by the Kjeldahl method in GB 50095-2010 Determination of Protein in Foods for the above two experimental results, and the contents were 0.8356 g / 100 mL and 0.9934 g / 100 mL, respectively; which are basically consistent with the results obtained by the present invention.

[0047] Based on the data from the two experiments, we can quickly learn the changes in the degree of hydrolysis under different reaction conditions, and quickly screen the optimal hydrolysis conditions, providing convenience for workshop production.

[0048] Example 2

[0049] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.02% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in GB 50095-2010 Determination of Protein in Food, and measure the refractive index with a refractometer;

[0050] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.05% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in GB 50095-2010 Determination of Protein in Food, and measure the refractive index with a refractometer;

[0051] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.5% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in GB 50095-2010 Determination of Protein in Food, and measure the refractive index with a refractometer;

[0052] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 1% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in GB 50095-2010 Determination of Protein in Food, and measure the refractive index with a refractometer;

[0053] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 2% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0054] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 4% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in GB 50095-2010 Determination of Protein in Food, and measure the refractive index with a refractometer;

[0055] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 6% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0056] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 8% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in GB 50095-2010 Determination of Protein in Food, and measure the refractive index with a refractometer;

[0057] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50°C, add 10% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 10000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer.

[0058] Table 2 Relationship between refractive index and water-soluble protein peptide content

[0059]

[0060] According to the data in Table 2, a standard curve was drawn with the water-soluble protein peptide content of the supernatant as the abscissa and the refractive index of the supernatant as the ordinate, and the standard curve y=1.6843X+0.065, R2=0.9981 was obtained.

[0061] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50°C, add 1% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 6000 r / min, take the supernatant, measure the refractive index with a refractometer, and obtain: 4.62, substitute 4.62 into the standard curve y=1.6843X+0.065, and obtain the corresponding water-soluble protein peptide content of 2.7044 g / 100 mL;

[0062] Weigh 266.64 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 30°C, add 2% alkaline protease based on the mass of the walnut kernels, react for 2 hours, centrifuge at 10000 r / min, take the supernatant, and measure the refractive index with a refractometer to obtain: 4.25, substitute 4.25 into the standard curve y=1.6843X+0.065, and obtain the corresponding water-soluble protein peptide content of 2.4847 g / 100 mL.

[0063] Verification: The water-soluble protein peptide contents were measured by the method of "GB 50095-2010 Determination of Protein in Food" for the above two experimental results, and the contents were 2.7036 g / 100 mL and 2.4856 g / 100 mL, respectively; which are basically consistent with the results obtained by the present invention.

[0064] Based on the data from the two experiments, we can quickly learn the changes in the degree of hydrolysis under different reaction conditions, and quickly screen the optimal hydrolysis conditions, providing convenience for workshop production.

[0065] Example 3

[0066] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.02% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0067] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.05% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0068] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 0.5% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0069] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 1% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0070] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 2% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0071] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 4% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0072] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 6% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0073] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50° C., add 8% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0074] Weigh 160 g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 50°C, add 10% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 8000 r / min for 10 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer.

[0075] Table 3 Relationship between refractive index and water-soluble protein peptide content

[0076]

[0077] According to the data in Table 3, a standard curve was drawn with the water-soluble protein peptide content of the supernatant as the abscissa and the refractive index of the supernatant as the ordinate, and the standard curve y=1.6816X+0.0663, R2=0.9984 was obtained.

[0078] Weigh 160g of walnut kernels, crush the walnut kernels with a colloid mill under anhydrous conditions, add water to 800g to obtain a mixed solution, heat to 30°C, add 8% alkaline protease based on the mass of the walnut kernels, react for 4 hours, centrifuge at 6000r / min, take the supernatant, measure the refractive index with a refractometer, and obtain: 3.46, substitute 3.46 into the standard curve y=1.6816X+0.0663, and obtain the corresponding water-soluble protein peptide content of 2.0181g / 100mL;

[0079] Weigh 160g of walnut kernels, crush them with a colloid mill under anhydrous conditions, add water to 800g to obtain a mixed solution, heat to 50°C, add 6% alkaline protease based on the mass of the walnut kernels, react for 2 hours, centrifuge at 10000r / min, take the supernatant, measure the refractive index with a refractometer, and obtain: 3.61, add 3.61 to the standard curve y=1.6816X+0.0663, and obtain the corresponding water-soluble protein peptide content of 2.1073g / 100mL;

[0080] Verification: The water-soluble protein peptide contents were measured by the method of GB 50095-2010 Determination of Protein in Food for the above two experimental results, and the contents were 2.0176 g / 100 mL and 2.1079 g / 100 mL, respectively; which were basically consistent with the results obtained by the present invention.

[0081] Based on the data from the two experiments, we can quickly learn the changes in the degree of hydrolysis under different reaction conditions, and quickly screen the optimal hydrolysis conditions, providing convenience for workshop production.

[0082] Example 4

[0083] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40°C, add 0.02% alkaline protease based on the mass of soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0084] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40° C., add 0.05% alkaline protease based on the mass of soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in GB 50095-2010 Determination of Protein in Food, and measure the refractive index with a refractometer;

[0085] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40°C, add 0.5% alkaline protease based on the mass of soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0086] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40°C, add 1% alkaline protease based on the mass of soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0087] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40°C, add 2% alkaline protease based on the mass of the soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0088] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40°C, add 4% alkaline protease based on the mass of soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0089] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40°C, add 6% alkaline protease based on the mass of soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0090] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40°C, add 8% alkaline protease based on the mass of soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer;

[0091] Weigh 135 g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800 g to obtain a mixed solution, heat to 40°C, add 10% alkaline protease based on the mass of the soybeans, react for 4 hours, centrifuge at 6000 r / min for 15 min, take the supernatant, measure the water-soluble protein peptide content according to the Kjeldahl method in "GB 50095-2010 Determination of Protein in Food", and measure the refractive index with a refractometer.

[0092] Table 4 Relationship between refractive index and water-soluble protein peptide content

[0093]

[0094]

[0095] According to the data in Table 4, a standard curve was drawn with the water-soluble protein peptide content of the supernatant as the abscissa and the refractive index of the supernatant as the ordinate, and the standard curve y=1.6837X+0.0712, R2=0.9982 was obtained.

[0096] Weigh 135g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800g to obtain a mixed solution, heat to 70°C, add 1% alkaline protease based on the mass of soybeans, react for 6 hours, centrifuge at 6000r / min, take the supernatant, measure the refractive index with a refractometer, and obtain: 2.83, substitute 2.83 into the standard curve y=1.6837X+0.0712, and obtain the corresponding water-soluble protein peptide content of 1.6385g / 100mL;

[0097] Weigh 135g of soybeans, crush walnut kernels with a colloid mill under anhydrous conditions, add water to 800g to obtain a mixed solution, heat to 60°C, add 1.5% alkaline protease based on the mass of soybeans, react for 3 hours, centrifuge at 6000r / min, take the supernatant, measure the refractive index with a refractometer, and obtain: 3.02, substitute 3.02 into the standard curve y=1.6837X+0.0712, and obtain the corresponding water-soluble protein peptide content of 1.7514g / 100mL;

[0098] Verification: The water-soluble protein peptide contents were measured by the method of GB 50095-2010 Determination of Protein in Food for the above two experimental results, and the contents were 1.6365 g / 100 mL and 1.7528 g / 100 mL, respectively; which were basically consistent with the results obtained by the present invention.

[0099] Based on the data from the two experiments, we can quickly learn the changes in the degree of hydrolysis under different reaction conditions, and quickly screen the optimal hydrolysis conditions, providing convenience for workshop production.

[0100] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for rapidly detecting the content of water-soluble protein peptides for use in determining the degree of protein hydrolysis, characterized in that: The specific steps include: Step 1: Determine the refractive index of a sample with a known water-soluble protein peptide content and establish a standard curve of refractive index-water-soluble protein peptide content; Step 2: Detect the refractive index of the substance to be tested; Step 3: Substitute the refractive index into the standard curve obtained in step 1 to obtain the water-soluble protein peptide content in the substance to be tested; Step 1 specifically includes: The plant protein raw material is weighed and crushed, water is added to the crushed material to obtain a mixed solution, the mixed solution is heated, different amounts of enzymes are added to perform a hydrolysis reaction, the supernatant is collected by centrifugation, the refractive index is measured, and the water-soluble protein peptide content is detected by the Kjeldahl method. According to the corresponding relationship, a standard curve of refractive index-water-soluble protein peptide content is established. The mass ratio of the plant protein raw material to water is 1:2 to 1:10; In the preparation of the water-soluble protein peptide to be tested, the amount of the enzyme added is 1% to 3.5% of the mass of the plant protein raw material, based on the mass of the plant protein raw material.

2. The use of the method for rapid detection of water-soluble protein peptide content according to claim 1 in determining the degree of protein hydrolysis, characterized in that: Under anhydrous conditions, the plant protein raw materials are crushed using a colloid mill.

3. The use of the method for rapid detection of water-soluble protein peptide content according to claim 2 in determining the degree of protein hydrolysis, characterized in that: The heating temperature is 30°C to 80°C.

4. The use of the method for rapid detection of water-soluble protein peptide content according to claim 3 in determining the degree of protein hydrolysis, characterized in that: The enzyme includes one or more of papain, alkaline protease, bacterial protease and trypsin.

5. The use of the method for rapid detection of water-soluble protein peptide content according to claim 4 in determining the degree of protein hydrolysis, characterized in that: The centrifugal conditions are: 6000r / min~10000r / min, centrifugation for 5 min~15 min.

6. The use of the method for rapid detection of water-soluble protein peptide content according to claim 5 in determining the degree of protein hydrolysis, characterized in that: The plant protein raw material is walnut and / or soybean.

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