Method for detecting sweetness of rice

Abstract

The application relates to a rice sweetness detection method, which simulates an oral processing process in vitro, combines instrument analysis and sensory evaluation, describes the change of sweet substances in rice during chewing, and can objectively and accurately describe the sweetness condition of the rice.

Description

Technical Field

[0001] This invention relates to the field of food analysis, specifically to a method for detecting the sweetness of cooked rice. Background Technology

[0002] Rice is the staple food of Chinese residents. With the improvement of people's living standards, the taste and quality of rice are receiving increasing attention. GB / T 15682-2008, "Sensory Evaluation Method for the Cooking and Eating Quality of Paddy Rice and Rice (Grain and Oil Inspection)," evaluates the eating quality of rice from five aspects: odor, appearance and structure, palatability, taste, and texture of cold rice. The best description for taste is "a rich, fragrant aroma and sweetness when chewed." Sweetness is one of the most beloved taste stimuli for humans. Rice with a sweet taste and a lingering aftertaste is increasingly favored by consumers, leading to growing market demand. There are significant differences in the sweetness intensity of rice from different origins and varieties, attributed to differences in the types and amounts of sweetening substances. However, current research on the evaluation of rice sweetness is limited, possibly due to the relatively low intensity of sweetness in the overall taste profile.

[0003] The sweetness in food comes from soluble components dissolving in saliva, stimulating taste buds on the tongue, and then being transmitted to the taste center in the brain via taste nerve fibers. When tasting rice, the main source of sweetness is the breakdown of starch into soluble sugars such as glucose and maltose by amylase. In addition, some amino acids, such as phenylalanine, serine, and threonine, also contribute to the sweetness.

[0004] During the human digestive process, the mouth undergoes a certain processing of rice. Modern sensory science research confirms that the structure of food is broken down and its chemical composition is altered during chewing in the mouth, releasing aroma components, which plays an important role in the taste experience. However, directly detecting changes in food flavor substances during human oral chewing is challenging and lacks stability. Therefore, it is necessary to study the changes in sweet substances in rice during chewing by simulating the oral processing process in vitro. Summary of the Invention

[0005] To address the aforementioned issues, the inventors of this application have developed a method for detecting the sweetness of cooked rice. This method simulates the oral processing process in vitro and combines instrumental analysis and sensory evaluation to describe the changes in sweet substances in cooked rice during chewing. It can objectively and accurately describe the sweetness of cooked rice, and the quantification of sweetness will also provide a research basis for judging the quality of cooked rice.

[0006] Therefore, in a first aspect, the present invention provides a method for detecting the sweetness of cooked rice, comprising:

[0007] (1) The cooked rice is mixed with artificial saliva, calcium chloride and proteolytic enzyme in sequence, wherein the artificial saliva contains amylase and sucrase;

[0008] (2) Centrifuge the product obtained in step (1) and take the supernatant;

[0009] (3) Obtain the content of soluble sugars and amino acids in the supernatant, wherein the soluble sugars include glucose, sucrose, fructose, maltose, and raffinose, and the amino acids include threonine, serine, glycine, proline, alanine, phenylalanine, and tryptophan;

[0010] (4) Obtain the sweetness of the steamed rice;

[0011] (5) Select indicators from the soluble sugars and amino acids in step (3) that simultaneously satisfy the following conditions A and B as independent variables, and use the sweetness of the steamed rice described in step (4) as the dependent variable. Construct a rice sweetness prediction equation by fitting multiple linear regression.

[0012] Condition A: Taste Intensity Value (TAV) greater than 1.

[0013] Condition B: Significantly correlated with the sweetness of the steamed rice obtained in step (4);

[0014] (6) Repeat steps (1)-(3) on the steamed rice to be tested to obtain the content of the indicators that meet conditions A and B in the supernatant to be tested;

[0015] (7) Substitute the content of the indicators that satisfy conditions A and B obtained in step (6) into the rice sweetness prediction equation obtained in step (5) to determine the sweetness of the rice to be tested.

[0016] The phrase "mixing the steamed rice with artificial saliva, calcium chloride, and proteolytic enzyme in sequence" refers to mixing the steamed rice with artificial saliva and calcium chloride first, and then further mixing it with the proteolytic enzyme.

[0017] In some implementations, condition B is determined through correlation analysis.

[0018] In some implementations, the significance level p < 0.05 is specified in condition B.

[0019] In some implementations, the correlation analysis is Spearman correlation analysis.

[0020] In some embodiments, in step (1), the concentration of the amylase in the artificial saliva is 100-200 U / mL (e.g., 100-110 U / mL, 110-120 U / mL, 120-130 U / mL, 130-140 U / mL, 140-150 U / mL, 150-160 U / mL, 160-170 U / mL, 170-180 U / mL, 180-190 U / mL, or 190-200 U / mL), and the concentration of the sucrase in the artificial saliva is... 1-20U / mL (such as 1-2U / mL, 2-3U / mL, 3-4U / mL, 4-5U / mL, 5-6U / mL, 6-7U / mL, 7-8U / mL, 8-9U / mL, 9-10U / mL, 10-11U / m L, 11-12U / mL, 12-13U / mL, 13-14U / mL, 14-15U / mL, 15-16U / mL, 16-17U / mL, 17-18U / mL, 18-19U / mL or 19-20U / mL).

[0021] In some implementations, in step (1), the weight ratio of the steamed rice to the volume of the artificial saliva is 5g-10g:5mL-10mL, for example, 5g:5mL, 6g:5mL, 7g:5mL, 8g:5mL, 9g:5mL, 10g:5mL, 5g:6mL, 6g:6mL, 7g:6mL, 8g:6mL, 9g:6mL, 10g:6mL, 5g:7mL, 6g:7mL, 7g: 7mL, 8g:7mL, 9g:7mL, 10g:7mL, 5g:8mL, 6g:8mL, 7g:8mL, 8g:8mL, 9g:8mL, 10g:8mL, 5g:9mL, 6g:9m L, 7g:9mL, 8g:9mL, 9g:9mL, 10g:9mL, 5g:10mL, 6g:10mL, 7g:10mL, 8g:10mL, 9g:10mL or 10g:10mL.

[0022] In some embodiments, in step (1), the concentration of calcium chloride in the mixture of cooked rice and artificial saliva is 0.7-0.8 mmol / L (e.g., 0.71-0.72 mmol / L, 0.72-0.73 mmol / L, 0.73-0.74 mmol / L, 0.74-0.75 mmol / L, 0.75-0.76 mmol / L, 0.76-0.77 mmol / L, 0.77-0.78 mmol / L, 0.78-0.79 mmol / L or 0.79-0.80 mmol / L), preferably 0.75 mmol / L.

[0023] In some embodiments, in step (1), the concentration of the proteolytic enzyme in the mixture of the cooked rice and the artificial saliva is 10-150 U / mL (e.g., 10-20 U / mL, 20-30 U / mL, 30-40 U / mL, 40-50 U / mL, 50-60 U / mL, 60-70 U / mL, 70-80 U / mL, 80-90 U / mL, 90-100 U / mL, 100-110 U / mL, 110-120 U / mL, 120-130 U / mL, 130-140 U / mL or 140-150 U / mL), preferably 70 U / mL.

[0024] In some implementations, in step (3), the content of the soluble sugar is obtained in accordance with GB 5009.8-2016, and the content of the amino acids is obtained in accordance with GB 5009.124-2016.

[0025] In some implementations, in step (4), the sweetness of the steamed rice is obtained by the following sweetness quantification scoring method:

[0026] Sucrose solutions of different concentration gradients (i.e., 0 mg / mL, 2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, and 10 mg / mL) were used to represent sweetness reference solutions of 0, 2, 4, 6, 8, and 10 points, respectively. The cooked rice was evaluated according to the evaluation method of GB / T 15682-2008 to obtain the quantified sweetness of the cooked rice.

[0027] In some embodiments, the artificial saliva further comprises: KCl, KH2PO4, NaHCO3, MgCl2(H2O)6, and (NH4)2CO3.

[0028] In some embodiments, the concentration of KCl is 15.0-15.5 mmol / L (e.g., 15.0-15.1 mmol / L, 15.1-15.2 mmol / L, 15.2-15.3 mmol / L, 15.3-15.4 mmol / L or 15.4-15.5 mmol / L), preferably 15.1 mmol / L.

[0029] In some embodiments, the concentration of KH2PO4 is 3.5-4.0 mmol / L (e.g., 3.5-3.6 mmol / L, 3.6-3.7 mmol / L, 3.7-3.8 mmol / L, 3.8-3.9 mmol / L or 3.9-4.0 mmol / L), preferably 3.7 mmol / L.

[0030] In some embodiments, the concentration of NaHCO3 is 13.5-14.0 mmol / L (e.g., 13.5-13.6 mmol / L, 13.6-13.7 mmol / L, 13.7-13.8 mmol / L, 13.8-13.9 mmol / L or 13.9-14.0 mmol / L), preferably 13.6 mmol / L.

[0031] In some embodiments, the concentration of MgCl2(H2O)6 is 0.13-0.17 mmol / L (e.g., 0.13-0.14 mmol / L, 0.14-0.15 mmol / L, 0.15-0.16 mmol / L or 0.16-0.17 mmol / L), preferably 0.15 mmol / L.

[0032] In some embodiments, the concentration of (NH4)2CO3 is 0.05-0.1 mmol / L (e.g., 0.05-0.06 mmol / L, 0.06-0.07 mmol / L, 0.07-0.08 mmol / L, 0.08-0.09 mmol / L or 0.09-0.1 mmol / L), preferably 0.06 mmol / L.

[0033] In some implementations, the pH of the artificial saliva is 7.0.

[0034] In some embodiments, the pH of the artificial saliva is adjusted using a sodium hydroxide solution.

[0035] In some embodiments, the concentration of sodium hydroxide is 5-7 mol / L (preferably 6 mol / L).

[0036] In some embodiments, the artificial saliva is prepared by the following method:

[0037] 1) Mix the KCl, KH2PO4, NaHCO3, MgCl2(H2O)6 and (NH4)2CO3, dissolve them in water, and then adjust the pH to 7.0 with sodium hydroxide solution;

[0038] 2) Add the amylase and sucrase to the solution obtained in step 1) to obtain the artificial saliva.

[0039] In some implementations, in step (1), the artificial saliva is preheated to 37°C before the cooked rice is mixed with the artificial saliva.

[0040] In some implementations, in step (1), the cooked rice is mixed with artificial saliva and calcium chloride in sequence, and the mixture is squeezed and stirred at a temperature of 37°C for 1-5 minutes (e.g., 1 minute, 2 minutes, 3 minutes, 4 minutes or 5 minutes). Then, proteolytic enzyme is added, and the mixture is squeezed and stirred again at a temperature of 37°C for 1-5 minutes (e.g., 1 minute, 2 minutes, 3 minutes, 4 minutes or 5 minutes).

[0041] In some embodiments, after the re-extrusion and stirring at a temperature of 37°C for 1-5 minutes (e.g., 1 minute, 2 minutes, 3 minutes, 4 minutes, or 5 minutes), the reaction is further terminated by adding 1 mL of 10% trichloroacetic acid.

[0042] In some specific implementation schemes, the rice sweetness prediction equation constructed in step (5) is: Sweetness = 1.694 * glucose + 1.638 * sucrose + 1.107 * maltose + 0.998 * alanine + 2.058 * glycine - 9.484, R 2 =0.862.

[0043] In some implementations, the cooked rice is obtained by adding 1-2 times (e.g., 1.5 times) the amount of distilled water used to sample the rice, soaking it at room temperature for 20-40 minutes (e.g., 30 minutes), selecting the fast cooking program on a rice cooker, and then simmering it for another 10-30 minutes (e.g., 20 minutes) after completion to obtain the cooked rice.

[0044] Beneficial effects

[0045] The present invention has the following advantages and advancements:

[0046] (1) The sweetness detection method of the present invention has a measurement condition that is closer to the actual chewing process in the human mouth, and the measurement results are more objective and accurate.

[0047] (2) The sweetness of the rice to be tested (e.g., 10 portions) was evaluated using the sweetness detection method of the present invention, and the results obtained were more consistent with the sensory evaluation results.

[0048] (3) The sweetness detection method of the present invention measures the sweet substances in rice tasting, avoiding the bias caused by subjective factors and physiological state in sensory evaluation, and improving the detection accuracy. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the process for detecting the sweetness of rice. Detailed Implementation

[0050] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples. However, those skilled in the art will understand that the following drawings and examples are for illustrative purposes only and are not intended to limit the scope of the invention. Various objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description of the drawings and preferred embodiments.

[0051] This invention provides a method for detecting the sweetness of cooked rice, such as... Figure 1 As shown.

[0052] In one embodiment of the present invention, the technical solution adopted by the rice sweetness detection method is as follows:

[0053] (1) Add 1.5 times the amount of distilled water to the cleaned rice, soak at room temperature for 30 minutes, use the fast cooking program of the rice cooker (such as SF40HC42 Suppor), and simmer for another 20 minutes after completion. Keep warm and use later.

[0054] (2) Prepare artificial saliva in advance. Before use, artificial saliva needs to be preheated to 37°C.

[0055] (3) Weigh 5-10g of the rice from step (1), add 5-10mL of the artificial saliva from step (2), add CaCl2 to make the final concentration 0.75mmol / L, squeeze and stir at 37℃ for 1-5min, then add proteolytic enzyme to make the final concentration 70U / mL, squeeze and stir at 37℃ for 1-5min, and add 1mL of 10% trichloroacetic acid to terminate the reaction.

[0056] (4) Centrifuge the mixture in step (3) and determine the content of soluble sugars such as glucose, sucrose, fructose, maltose, and raffinose, and amino acids such as threonine, serine, glycine, proline, alanine, phenylalanine, and tryptophan in the supernatant.

[0057] (5) The sweetness of rice is evaluated by a taste quantification scoring method (such as a sweetness quantification scoring method).

[0058] In one embodiment of the present invention, the method for preparing artificial saliva includes the following steps:

[0059] (A) The components include 15.1 mmol / L KCl, 3.7 mmol / L KH2PO4, 13.6 mmol / L NaHCO3, 0.15 mmol / L MgCl2(H2O)6, and 0.06 mmol / L (NH4)2CO3, and then the pH is adjusted to 7.0 with 6 mol / L sodium hydroxide solution;

[0060] (B) Add amylase and sucrase to the mixture obtained in (A) to make their final concentrations 100-200 U / mL and 1-20 U / mL, respectively.

[0061] In one embodiment of the present invention, the determination of the sugar content of glucose, sucrose, fructose, maltose, raffinose, etc., is carried out in accordance with GB 5009.8-2016.

[0062] In one embodiment of the present invention, the content of amino acids such as threonine, serine, glycine, proline, alanine, phenylalanine, and tryptophan is determined in accordance with GB 5009.124-2016.

[0063] In one embodiment of the present invention, the material parameters related to the sweetness of rice include soluble sugars such as glucose, sucrose, fructose, maltose, and raffinose, and amino acids such as threonine, serine, glycine, proline, alanine, phenylalanine, and tryptophan. Indicators with a TAV (taste activity value) greater than 1 and significantly correlated with sweetness are selected, and a rice sweetness prediction equation is further constructed by fitting multiple linear regression.

[0064] In one embodiment of the present invention, the sweetness of rice is quantitatively evaluated using the following method:

[0065] Different concentration gradients of sucrose solutions (0, 2, 4, 6, 8, 10 mg / mL) were used to represent sweetness reference solutions of 0, 2, 4, 6, 8, and 10 points, respectively. The rice obtained in step (1) was compared and evaluated according to the evaluation method of GB / T 15682-2008 to quantify the sweetness of different rice.

[0066] The present invention will be further described below with reference to specific embodiments.

[0067] Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional in the art. Unless otherwise specified, all reagents used in the embodiments of this invention are commercially available. Specifically, amylase, proteolytic enzyme, and sucrase were purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0068] Preliminary Example: Preparation of Artificial Saliva

[0069] (A) The components include 15.1 mmol / L KCl, 3.7 mmol / L KH2PO4, 13.6 mmol / L NaHCO3, 0.15 mmol / L MgCl2(H2O)6, and 0.06 mmol / L (NH4)2CO3, and then the pH is adjusted to 7.0 with 6 mol / L sodium hydroxide solution;

[0070] (B) Add amylase and sucrase to the mixture obtained in (A) to make their final concentrations 150 U / mL and 5 U / mL, respectively.

[0071] Example 1: Method for detecting the sweetness of cooked rice

[0072] Step 1: Add 1.5 times the amount of distilled water to each of the 30 portions of cleaned rice, soak at room temperature for 30 minutes, cook on the fast cooking program in a rice cooker, and then let it simmer for another 20 minutes after cooking. Keep warm and set aside.

[0073] Step 2: Preheat the artificial saliva obtained in the aforementioned preliminary embodiment to 37°C.

[0074] Step 3: Weigh 5g of the cooked rice from Step 1, add 5mL of the artificial saliva from Step 2, add CaCl2 to make the final concentration 0.75mmol / L, squeeze and stir at 37℃ for 3min, add proteolytic enzyme to make the final concentration 70U / mL, squeeze and stir at 37℃ for 3min, and add 1mL of 10% trichloroacetic acid to terminate the reaction.

[0075] Step 4: Determine the content of soluble sugars such as glucose, sucrose, fructose, maltose, and raffinose in the rice after stirring, referring to GB 5009.8-2016. Determine the content of amino acids such as threonine, serine, glycine, proline, alanine, phenylalanine, and tryptophan, referring to GB 5009.124-2016.

[0076] Step 5: Using sucrose solutions of different concentration gradients (0, 2, 4, 6, 8, 10 mg / mL) to represent sweetness reference solutions of 0, 2, 4, 6, 8, and 10 points respectively, the rice obtained in step (1) is compared and evaluated according to the evaluation method of GB / T 15682-2008 to quantify the sweetness of different rice.

[0077] Step 6: Select indicators with a TAV (Taste Intensity Value) greater than 1 and significantly correlated with sweetness (P<0.05), and further construct a rice sweetness prediction equation through multiple linear regression fitting. The calculation of TAV (Taste Intensity Value) is well known to those skilled in the art.

[0078] Spearman correlation analysis was performed on the indicators with TAV greater than 1 and the aforementioned rice sweetness.

[0079] The indicators selected above with a TAV (taste intensity value) greater than 1 and significantly correlated with sweetness (P<0.05) were used as independent variables, and the sweetness of the rice obtained in step 5 was used as the dependent variable. A rice sweetness prediction equation was constructed by fitting multiple linear regression.

[0080] The resulting equation for predicting the sweetness of cooked rice is: Sweetness = 1.694 * glucose + 1.638 * sucrose + 1.107 * maltose + 0.998 * alanine + 2.058 * glycine - 9.484, R 2 =0.862.

[0081] Step 7: Repeat steps 1-4 of the previous steps for the rice to be tested, and then input the content of the indicators obtained from the screening into the equation obtained in step 6 to determine the sweetness of the rice to be tested.

[0082] Example 2: Verification Experiment

[0083] Step 1: Add 1.5 times the amount of distilled water to each of the 10 types of cleaned rice, soak at room temperature for 30 minutes, use the quick cook program on a rice cooker, and let it simmer for another 20 minutes after completion. Keep warm and set aside.

[0084] Step 2: Using sucrose solutions of different concentration gradients (0, 2, 4, 6, 8, 10 mg / mL) to represent sweetness reference solutions of 0, 2, 4, 6, 8, and 10 points respectively, the above 10 types of rice were evaluated according to GB / T 15682-2008 to quantify the sweetness of different types of rice.

[0085] Step 3: Using the rice sweetness detection method of Example 1, obtain the content of the indicators screened in Example 1.

[0086] The sweetness of the 10 types of rice was obtained by substituting the content of each indicator into the equation constructed in Example 1.

[0087] Step 4: Compare the evaluation results obtained in Step 2 with the test results obtained in Step 3. The results are shown in Table 1.

[0088] As shown in Table 1, the average relative error of the prediction results is 22.4%, and the root mean square error is 0.97. The smaller the average relative error and root mean square error of the prediction results, the more accurate the prediction results. Since the average relative error and root mean square error of the aforementioned prediction results are both small, this model has certain reference value for predicting the sweetness value of rice and has high accuracy.

[0089] Table 1 Prediction Results of Model 1

[0090]

[0091] Comparative Example 1

[0092] 1. Comparative Testing Method for Rice Sweetness

[0093] Steps 1 through 6 are exactly the same as in Example 1. Therefore, the resulting rice sweetness prediction equation remains: Sweetness = 1.694 * glucose + 1.638 * sucrose + 1.107 * maltose + 0.998 * alanine + 2.058 * glycine - 9.484, R 2 =0.862.

[0094] Step 7: Add 1.5 times the amount of distilled water to the rice to be tested, soak at room temperature for 30 minutes, use the fast cooking program on a rice cooker, and let it simmer for another 20 minutes after completion. Keep warm and set aside for later use.

[0095] Step 8: Preheat the artificial saliva obtained in the aforementioned preliminary example to 37°C without adding sucrase (the rest of the steps remain the same).

[0096] Step 9: Weigh 5g of the cooked rice from Step 7, add 5mL of the artificial saliva from Step 8, add CaCl2 to make the final concentration 0.75mmol / L, squeeze and stir at 37℃ for 3min, and add 1mL of 10% trichloroacetic acid to terminate the reaction.

[0097] Step 10: Determine the content of glucose, sucrose, and maltose in the rice after stirring according to GB 5009.8-2016, and determine the content of glycine and alanine according to GB 5009.124-2016.

[0098] Step 11: Substitute the contents of glucose, sucrose, maltose, glycine, and alanine obtained in Step 10 into the equation obtained in Step 6 (i.e., sweetness = 1.694 * glucose + 1.638 * sucrose + 1.107 * maltose + 0.998 * alanine + 2.058 * glycine - 9.484, R). 2 =0.862), which can be used to determine the sweetness of the rice to be tested.

[0099] 2. Comparative Verification Experiment 1

[0100] Step 1: Add 1.5 times the amount of distilled water to each of the 10 types of cleaned rice (which are exactly the same as the 10 types of rice in Example 2), soak at room temperature for 30 minutes, use the fast cooking program in a rice cooker, and then let it simmer for another 20 minutes after completion. Keep warm and set aside for later use.

[0101] Step 2: Using sucrose solutions of different concentration gradients (0, 2, 4, 6, 8, 10 mg / mL) to represent sweetness reference solutions of 0, 2, 4, 6, 8, and 10 points respectively, the above 10 types of rice were evaluated according to GB / T 15682-2008 to quantify the sweetness of different types of rice.

[0102] Step 3: Using the aforementioned comparative detection method 1 for rice sweetness, obtain the contents of glucose, sucrose, maltose, glycine, and alanine.

[0103] Substituting the contents into the equation (i.e., sweetness = 1.694 * glucose + 1.638 * sucrose + 1.107 * maltose + 0.998 * alanine + 2.058 * glycine - 9.484), R 2 =0.862) to obtain the sweetness of the above 10 types of rice.

[0104] Step 4: Compare the evaluation results obtained in Step 2 with the test results obtained in Step 3. The results are shown in Table 2.

[0105] As shown in Table 2, the average relative error of the prediction results is 31.5%, and the root mean square error is 1.4.

[0106] As can be seen from the comparison results in Tables 2 and 1, compared with the comparative detection method 1 for rice sweetness, the detection method of this application has significantly smaller average relative error and root mean square error, and the detection results are more accurate and reliable.

[0107] Table 2 Prediction Results of Model 1

[0108]

[0109] Comparative Example 2

[0110] 1. Comparative testing method for the sweetness of cooked rice 2

[0111] Steps 1 through 5 are exactly the same as in Example 1.

[0112] Step 6: Select indicators that are significantly correlated with sweetness (P<0.05), and further construct a rice sweetness prediction equation by fitting multiple linear regression.

[0113] Significant correlation with sweetness was determined using Spearman correlation analysis.

[0114] The indicators that were significantly correlated with sweetness (P<0.05) selected above were used as independent variables, and the sweetness of the rice obtained in step 5 was used as the dependent variable. A rice sweetness prediction equation was constructed by fitting multiple linear regression.

[0115] The resulting equation for predicting the sweetness of cooked rice is: Sweetness = 1.633 * glucose + 1.515 * sucrose + 1.045 * maltose + 0.929 * alanine + 1.977 * glycine + 6.489 * fructose - 9.240, R 2 =0.863.

[0116] Step 7: Repeat steps 1-4 of the previous steps for the rice to be tested, and then input the content of the indicators obtained from the screening into the equation obtained in step 6 to determine the sweetness of the rice to be tested.

[0117] 2. Comparative verification experiment 2

[0118] Step 1: Add 1.5 times the amount of distilled water to each of the 10 types of cleaned rice (which are exactly the same as the 10 types of rice in Example 2), soak at room temperature for 30 minutes, use the fast cooking program in a rice cooker, and then let it simmer for another 20 minutes after completion. Keep warm and set aside for later use.

[0119] Step 2: Using sucrose solutions of different concentration gradients (0, 2, 4, 6, 8, 10 mg / mL) to represent sweetness reference solutions of 0, 2, 4, 6, 8, and 10 points respectively, the above 10 types of rice were evaluated according to GB / T 15682-2008 to quantify the sweetness of different types of rice.

[0120] Step 3: Using the aforementioned comparative detection method 2 for rice sweetness, obtain the content of the indicators screened by the comparative detection method 2 for rice sweetness.

[0121] Substituting the contents of each indicator into the equation constructed by the aforementioned comparative detection method 2 for rice sweetness (i.e., sweetness = 1.633 * glucose + 1.515 * sucrose + 1.045 * maltose + 0.929 * alanine + 1.977 * glycine + 6.489 * fructose - 9.240, R...), R... 2 =0.863) to obtain the sweetness of the above 10 types of rice.

[0122] Step 4: Compare the evaluation results obtained in Step 2 with the test results obtained in Step 3. The results are shown in Table 3.

[0123] As shown in Table 3, the average relative error of the prediction results is 22.5%, and the root mean square error is 0.97.

[0124] As can be seen from the comparison results of Table 3 and Table 1, the detection results of the detection method of this application are comparable in accuracy to the detection results of the comparative detection method 2 for rice sweetness. However, the detection method of this application has fewer indicators than the comparative detection method 2 for rice sweetness. Therefore, the detection method of this application saves more computing resources, has higher detection efficiency, and lower detection cost.

[0125] Table 3 Prediction results of Model 2

[0126]

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for detecting the sweetness of cooked rice, comprising: (1) The cooked rice is mixed sequentially with artificial saliva, calcium chloride, and proteolytic enzyme, wherein the artificial saliva contains amylase and sucrase; wherein, The concentration of the amylase in the artificial saliva is 100-200 U / mL; the concentration of the sucrase in the artificial saliva is 1-20 U / mL. The ratio of the weight of the steamed rice to the volume of the artificial saliva is 5g-10g:5mL-10mL; and The concentration of the proteolytic enzyme in the mixture of the steamed rice and the artificial saliva is 10-150 U / mL; (2) Centrifuge the product obtained in step (1) and take the supernatant; (3) Obtain the content of soluble sugars and amino acids in the supernatant, wherein the soluble sugars include glucose, sucrose, fructose, maltose, and raffinose, and the amino acids include threonine, serine, glycine, proline, alanine, phenylalanine, and tryptophan; (4) Obtain the sweetness of the steamed rice; (5) Select indicators from the soluble sugars and amino acids in step (3) that simultaneously satisfy conditions A and B as independent variables, and use the sweetness of the steamed rice described in step (4) as the dependent variable. Construct a rice sweetness prediction equation by fitting multiple linear regression. Condition A: Taste Intensity Value (TAV) greater than 1. Condition B: Significantly correlated with the sweetness of the steamed rice obtained in step (4); (6) Repeat steps (1)-(3) on the steamed rice to be tested to obtain the content of the indicators that meet conditions A and B in the supernatant to be tested; (7) Substitute the content of the indicators that satisfy conditions A and B obtained in step (6) into the rice sweetness prediction equation obtained in step (5) to determine the sweetness of the rice to be tested.

2. The method of claim 1, wherein, The rice sweetness prediction equation constructed in step (5) is: Sweetness = 1.694 * glucose + 1.638 * sucrose + 1.107 * maltose + 0.998 * alanine + 2.058 * glycine - 9.484, R 2 =0.

862.

3. The method of claim 1, wherein, Condition B was determined through correlation analysis.

4. The method of claim 3, wherein, In condition B, the significance level is p < 0.

05.

5. The method of claim 3, wherein, The correlation analysis was Spearman correlation analysis.

6. The method of claim 1, wherein, In step (1), the concentration of calcium chloride in the mixture of steamed rice and artificial saliva is 0.7-0.8 mmol / L.

7. The method of claim 1, wherein, In step (1), the concentration of calcium chloride in the mixture of steamed rice and artificial saliva is 0.75 mmol / L; Alternatively, in step (1), the concentration of the proteolytic enzyme in the mixture of the steamed rice and the artificial saliva is 70 U / mL.

8. The method of claim 1, wherein, In step (3), the content of soluble sugar is obtained in accordance with GB 5009.8-2016, and the content of amino acids is obtained in accordance with GB 5009.124-2016.

9. The method of claim 1, wherein, In step (4), the sweetness of the steamed rice is obtained through the following sweetness quantification scoring method: Sucrose solutions of different concentration gradients, namely 0 mg / mL, 2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, and 10 mg / mL, were used to represent sweetness reference solutions of 0, 2, 4, 6, 8, and 10 points, respectively. The cooked rice was evaluated according to the evaluation method of GB / T 15682-2008 to obtain the quantified sweetness of the cooked rice.

10. The method of claim 1, wherein, The artificial saliva further comprises: KCl, KH2PO4, NaHCO3, MgCl2(H2O)6 and (NH4)2CO3.

11. The method of claim 10, wherein, The concentration of KCl is 15.0-15.5 mmol / L.

12. The method of claim 11, wherein, The concentration of KCl was 15.1 mmol / L.

13. The method of claim 10, wherein, The concentration of KH2PO4 is 3.5-4.0 mmol / L.

14. The method of claim 13, wherein, The concentration of KH2PO4 was 3.7 mmol / L.

15. The method of claim 10, wherein, The concentration of NaHCO3 is 13.5-14.0 mmol / L.

16. The method of claim 15, wherein, The concentration of NaHCO3 was 13.6 mmol / L.

17. The method of claim 10, wherein, The concentration of MgCl2(H2O)6 is 0.13-0.17 mmol / L.

18. The method of claim 17, wherein, The concentration of MgCl2(H2O)6 is 0.15 mmol / L.

19. The method of claim 10, wherein, The concentration of (NH4)2CO3 is 0.05-0.1 mmol / L.

20. The method of claim 19, wherein, The concentration of (NH4)2CO3 was 0.06 mmol / L.

21. The method of claim 10, wherein, The pH of the artificial saliva is 7.

0.

22. The method of claim 10, wherein, The pH of the artificial saliva was adjusted using a sodium hydroxide solution.

23. The method of claim 22, wherein, The concentration of sodium hydroxide is 5-7 mol / L.

24. The method of claim 23, wherein, The concentration of sodium hydroxide is 6 mol / L.

25. The method of claim 10, wherein, The artificial saliva was prepared by the following method: 1) Mix the KCl, KH2PO4, NaHCO3, MgCl2(H2O)6 and (NH4)2CO3, dissolve them in water, and then adjust the pH to 7.0 with sodium hydroxide solution; 2) Add the amylase and sucrase to the solution obtained in step 1) to obtain the artificial saliva.

26. The method of claim 1, wherein, Step (1) further includes one or more of the following (1)-(3): (1) In step (1), before mixing the steamed rice with the artificial saliva, the artificial saliva is preheated to 37°C; (2) In step (1), the cooked rice is mixed with artificial saliva and calcium chloride in sequence, and the mixture is squeezed and stirred for 1-5 minutes at a temperature of 37°C. Then, proteolytic enzyme is added, and the mixture is squeezed and stirred again for 1-5 minutes at a temperature of 37°C. (3) After the mixture is squeezed and stirred again for 1-5 minutes at a temperature of 37°C, the reaction is further terminated by adding 1 mL of 10% trichloroacetic acid.

27. The method of claim 1, wherein, In step (1), the steamed rice is mixed with artificial saliva and calcium chloride in sequence, and the mixture is squeezed and stirred for 3 minutes at a temperature of 37°C. Then, proteolytic enzyme is added, and the mixture is squeezed and stirred again for 3 minutes at a temperature of 37°C.

28. The method of claim 1, wherein, The cooked rice is obtained by adding 1-2 times the amount of distilled water to the rice sample, soaking it at room temperature for 20-40 minutes, selecting the quick cook program on a rice cooker, and then simmering it for another 10-30 minutes after completion to obtain the cooked rice.

29. The method of claim 1, wherein, The cooked rice was obtained by adding 1.5 times the amount of distilled water to the rice sample, soaking it at room temperature for 30 minutes, selecting the quick cook program on a rice cooker, and then simmering it for another 20 minutes after completion to obtain the cooked rice.

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