Construction method and application of corn after-ripening comprehensive quality evaluation model

Abstract

The invention discloses a construction method and application of a corn after-ripening comprehensive quality evaluation model. The invention belongs to the technical field of comprehensive quality evaluation of corn after-ripening. The invention aims to solve the technical problem of lack of a corn after-ripening condition screening method. The method comprises the following steps: selecting newly-harvested corn cobs, and respectively storing the newly-harvested corn cobs in 15 DEG C and 25 DEG C constant-temperature and constant-humidity boxes for 0-60 days; sampling, threshing, freeze-drying and crushing every 10 days to obtain after-ripening corn flour; analyzing processing characteristics and digestion characteristics of the corn flour; and carrying out principal component analysis on each index of the processing characteristics and the digestion characteristics by adopting SPSS 21 software, and constructing an evaluation model. The quality evaluation model established by the invention is suitable for comprehensive quality evaluation of different varieties of corns, and lays a foundation for development and quality evaluation of high-quality corn foods.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive quality evaluation of corn after-ripening, and particularly relates to a method for constructing a comprehensive quality evaluation model for corn after-ripening and application thereof. Background Art

[0002] Corn is the world's largest grain crop, accounting for about 30-35% of the world's total grain production. The International Grains Council released a report in May 2024, saying that the global corn production in 2024-2025 is expected to be 1.22 billion tons. Therefore, corn processing plays an important role in the national economy. The moisture content of newly harvested corn is high, above 30%, with high respiration intensity and high lipid content. It is easy to absorb moisture and become rancid, and is not resistant to storage. Studies have shown that the starch extraction rate of newly harvested corn is low, and the resistant starch content is high, which is not conducive to consumption and further processing.

[0003] Corn needs to go through three stages during its maturity: milky, waxy and fully mature. Corn in Northeast China is usually harvested at the end of the waxy stage before the kernels are fully hard. Most of them are peeled and dried to complete post-ripening, and the moisture content drops to below 14% before they can be stored in warehouses. During the post-ripening period, the physiological and biochemical properties, physicochemical properties, nutritional components and processing quality of newly harvested corn are continuously improved. During the post-ripening process of corn, starch granules continue to develop, resulting in a rapid increase in starch content, an increase in short-chain starch, an increase in the proportion of double helix structure, an increase in short-range order and relative crystallinity, and thus an improvement in starch gelatinization and gel properties. In addition, the high content of resistant starch in newly harvested corn also affects corn digestion to a certain extent. The main reason why starch cannot be fully utilized by the small intestine is that the crystal area of ​​the starch granules resists the entry of water and its contact with enzymes, and the changes in starch structure during the post-ripening of corn will also affect its digestion characteristics. The content and structure of nutrient components in the post-ripening process of newly harvested corn will change significantly, which will affect the processing quality and digestion characteristics of corn flour. Summary of the invention

[0004] The purpose of the present invention is to provide a method for constructing a corn after-ripening comprehensive quality evaluation model and its application.

[0005] One of the purposes of the present invention is to provide a method for constructing a comprehensive quality evaluation model for corn ripening, the method being carried out according to the following steps:

[0006] (1) Select freshly harvested corn cobs with full kernels and store them in constant temperature and humidity chambers at 15°C and 25°C for 0 to 60 days respectively;

[0007] (2) taking samples every 10 days, threshing, freeze-drying, crushing, and sieving to obtain cooked corn flour;

[0008] (3) Analyze the processing characteristics and digestibility of corn flour. The processing characteristics include gelatinization, texture and rheological properties. The digestibility characteristics include the content of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS).

[0009] (4) SPSS21 software was used to perform principal component analysis on the above-mentioned processing characteristics and digestion characteristics. During the principal component analysis, the original data of the processing characteristics and digestion characteristics were first standardized using SPSS21 software, and then the standardized data were subjected to principal component analysis to analyze the principal component contribution rate of each indicator. The change trend of the top four principal components in terms of contribution rate was used to replace the change trend of the overall data. The top four principal components were named Z1, Z2, Z3, and Z4, respectively.

[0010] (5) SPSS21 software was used to derive the linear equations of Z1, Z2, Z3, Z4 and the processing characteristics and digestion characteristics. The variance contribution rates a1, a2, a3, a4 of the principal components Z1, Z2, Z3, Z4 were used as weights to construct the evaluation model.

[0011] It is further defined that the humidity in step (1) is 50-60%.

[0012] It is further defined that the humidity in step (1) is 55%.

[0013] It is further defined that the processing characteristics in step (3) include peak viscosity, disintegration value, recovery value, thixotropic ring area of ​​static rheology, gel hardness, gel elasticity, cohesion, and chewiness.

[0014] Further defined, the linear equations of Z1, Z2, Z3, and Z4 in step (4) are:

[0015] Z1=0.482×Z 回生值 +0.466×Z 崩解值 +0.446×Z 触变环面积 +0.440×Z 峰值黏度 -0.192×Z 硬度

[0016] -0.238×Z RDS +0.025×Z 咀嚼性 +0.172×Z 弹性 +0.073×Z SDS +0.167×Z RS -0.007×Z 内聚性 ;

[0017] Z2=0.115×Z 回生值 +0.082×Z 崩解值 +0.229×Z 触变环面积+0.242×Z 峰值黏度 +0.467×Z 硬度

[0018] +0.451×Z RDS +0.429×Z 咀嚼性 -0.345×Z 弹性 -0.197×Z SDS -0.259×Z RS -0.199×Z 内聚性 ;

[0019] Z3=0.067×Z 回生值 +0.034×Z 崩解值 +0.011×Z 触变环面积 +0.001×Z 峰值黏度 -0.126×Z 硬度

[0020] -0.032×Z RDS +0.135×Z 咀嚼性 -0.219×Z 弹性 +0.601×Z SDS -0.551×Z RS +0.496×Z 内聚性 ;

[0021] Z4=-0.044×Z 回生值 -0.101×Z 崩解值 +0.028×Z 触变环面积 -0.060×Z 峰值黏度 +0.193×Z 硬度

[0022] -0.146×Z RDS +0.168×Z 咀嚼性 +0.52×Z 弹性 +0.435×Z SDS -0.276×Z RS -0.599×Z 内聚性 .

[0023] It is further defined that the evaluation model in step (4) is: comprehensive quality Z = a1Z1+a2Z2+a3Z3+a4Z4.

[0024] The second object of the present invention is to provide an application of the above method in screening corn ripening conditions.

[0025] The third object of the present invention is to provide a method for preparing post-ripened corn flour with high processing and digestibility, the method being carried out according to the following steps:

[0026] Newly harvested corn cobs with full grains are selected, placed in a constant temperature and humidity box at 15-25° C. and 50-60% relative humidity for storage for 30-40 days, and then threshed, freeze-dried, crushed, and sieved to obtain ripened corn flour.

[0027] A fourth object of the present invention is to provide a post-ripened corn flour obtained by the above method.

[0028] A fifth object of the present invention is to provide a method for applying the above-mentioned ripened corn flour with high processing and digestion properties in the food field.

[0029] Compared with the prior art, the present invention has the following significant effects:

[0030] The present invention regulates the gelatinization characteristics, texture characteristics, rheological characteristics and digestion characteristics of corn flour through physiological activities and metabolic effects in the post-ripening process of newly harvested corn, performs principal component analysis with these processing and digestion properties as indicators, constructs a corn post-ripening quality evaluation model, and is used to evaluate the comprehensive quality of corn post-ripening and screen the optimal post-ripening conditions. The method is green, safe, low-cost and low-energy-consumption. The prepared corn flour has high processing and digestion characteristics. The established quality evaluation model is suitable for the comprehensive quality evaluation of different varieties of corn, laying a foundation for the development of high-quality corn food and its quality evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The peak viscosity changes of ripened corn flour of different varieties of corn stored at different temperatures for different periods of time; Figure A represents the corn variety JD, and Figure B represents the corn variety LY;

[0032] Figure 2 The disintegration value changes of ripened corn flour of different varieties of corn stored at different temperatures for different periods of time; Figure C represents the corn variety JD, and Figure D represents the corn variety LY;

[0033] Figure 3 The figure shows the changes in the retrogradation value of corn flour of different varieties of corn stored at different temperatures for different periods of time; Figure E represents the corn variety JD, and Figure F represents the corn variety LY;

[0034] Figure 4 The figure shows the changes in gel hardness of ripe corn flour of different varieties of corn stored at different temperatures for different periods of time; Figure A represents the corn variety JD, and Figure B represents the corn variety LY;

[0035] Figure 5 The figure shows the changes in gel elasticity of ripe corn flour of different varieties of corn stored at different temperatures for different periods of time; Figure C represents the corn variety JD, and Figure D represents the corn variety LY;

[0036] Figure 6The chewiness changes of corn flour from different varieties of corn stored at different temperatures for different periods of time; Figure E represents the corn variety JD, and Figure F represents the corn variety LY;

[0037] Figure 7 The cohesiveness changes of corn flour of different varieties of corn stored at different temperatures for different periods of time; Figure G represents the corn variety JD, and Figure H represents the corn variety LY;

[0038] Figure 8 The static rheological curves of corn JD after being stored at different temperatures for different time periods; Figure A represents 15°C, and Figure B represents 25°C;

[0039] Fig. 9 The static rheological curves of corn LY after being stored at different temperatures for different time periods; Figure C represents 15°C, and Figure D represents 25°C;

[0040] Fig.10 The dynamic rheological curves of storage modulus (G′) and loss modulus (G″) of ripe corn flour stored at 15°C for different time periods as a function of angular frequency; Figure A represents G′, and Figure B represents G″;

[0041] Fig.11 The dynamic rheological curves of storage modulus (G′) and loss modulus (G″) of ripe corn flour stored at 25°C for different time periods as a function of angular frequency; Figure C represents G′, and Figure D represents G″;

[0042] Fig.12 The dynamic rheological curves of storage modulus (G′) and loss modulus (G″) of ripe corn flour stored at 15°C for different time periods as a function of angular frequency; Figure E represents G′, and Figure F represents G″;

[0043] Fig.13 The dynamic rheological curves of storage modulus (G′) and loss modulus (G″) of ripened corn flour stored at 25°C for different time periods as a function of angular frequency; wherein Figure G represents G′ and Figure H represents G″. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0046] The terms "comprising," "including," "having," "containing," or any other variations thereof, as used in the following examples, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus comprising the listed elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0047] The "one embodiment" or "embodiment" of the present invention refers to a specific feature, structure or characteristic that can be included in at least one implementation of the present invention. The "in one embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0048] The endpoints and any values ​​of the ranges disclosed in the invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0049] The determination methods of the various indicators described in the following embodiments are as follows:

[0050] ① Determination of gelatinization characteristics of cooked corn flour

[0051] Accurately weigh 3g of corn flour sample into an aluminum box, add 25mL of distilled water, stir evenly and then measure. After the sample is kept at 50℃ for 1min, it is heated to 95℃ at 12℃ / min within 3.75min, kept at 95℃ for 2.5min, and then cooled to 50℃ within 3.75min.

[0052] ② Determination of gel texture characteristics of cooked corn flour

[0053] The corn flour paste after RVA measurement was placed in a 4℃ refrigerator for 24 hours to form a gel before measurement. Probe: P 0.5; parameter setting: pre-measurement speed 1.0mm / s, test speed 2.0mm / s, post-measurement speed 2.0mm / s, target mode: displacement, displacement distance: 10mm, time: 5s; trigger mode: automatic, trigger force: 5g.

[0054] ③ Determination of rheological properties of cooked corn flour

[0055] A corn flour paste was prepared by taking an 8% (m:v) corn flour sample and placing it on a rheometer using a plate-plate measuring system with a plate diameter of 4.0 cm and a setting gap of 1.0 mm.

[0056] Determination of static rheological properties: At a temperature of 25°C, the shear rate (γ) ranges from 0 to 300 s -1 Incrementally, from 300 to 0s -1 Decreasing. The power law model is used to regress the data points, and the equation is as follows:

[0057] τ=Kγ n

[0058] Where, τ is shear stress / Pa; K is consistency coefficient / (Pa·s n );γ—shear rate / s -1 ; n—fluid index.

[0059] Determination of dynamic viscoelastic properties: The samples were measured at a temperature of 25°C, an angular frequency of 0.1-100 rad / s, and a strain of 1%. The changes in storage modulus (G') and loss modulus (G") with angular frequency were recorded.

[0060] ④Determination of digestibility characteristics of ripened corn flour

[0061] The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) in corn flour were determined using a GOPOD kit.

[0062] RDS(%)=(G 20 -G0)×0.9 / TS

[0063] SDS(%)=(G 120 -G 20 )×0.9 / TS

[0064] RS (%) = [TS - (RDS + SDS)] / TS

[0065] Among them, G0, G 20 and G 120 They represent the glucose concentration of the sample after 0, 20 and 120 min of digestion respectively; TS is the total starch content in the sample.

[0066] Embodiment 1: The method for constructing a comprehensive quality evaluation model for ripened corn flour of this embodiment is carried out according to the following steps:

[0067] (1) Newly harvested corn cobs with full kernels from two varieties (Jidan 66 (JD) and Liangyu 99 (LY)) were selected and stored in constant temperature and humidity chambers at 15°C and 25°C and the same humidity (relative humidity 55%) for 0-60 days respectively;

[0068] (2) taking samples every 10 days, threshing, freeze-drying, crushing, and passing through an 80-mesh sieve to obtain post-ripened corn flour;

[0069] (3) Analyze the processing characteristics and digestibility of corn flour, specifically peak viscosity, disintegration value, regeneration value, thixotropic ring area of ​​static rheology, gel hardness, gel elasticity, cohesion, chewiness, RDS content, SDS content and RS content, and record the original data of each sample group;

[0070] Analysis of the results of each indicator response:

[0071] ① Gelatinization characteristics of corn flour during post-ripening

[0072] Peak viscosity refers to the maximum viscosity of starch paste before cooling. It is usually used to measure the free expansion capacity of starch granules and reflects the ability of corn flour to bind water. Peak viscosity is mainly related to amylose. The higher the amylose, the lower the peak viscosity. The peak viscosity of corn flour changes during the 60-day ripening of newly harvested corn at 15℃ and 25℃. Figure 1 As shown in the figure. Under the post-ripening conditions of the two varieties of corn at two temperatures, the peak viscosity of the corn flour showed a trend of increasing first and then decreasing. During the gelatinization process, corn flour was subjected to shear force, and the sample particles began to break after expanding to the maximum extent, and the viscosity of the system decreased rapidly, showing the lowest viscosity.

[0073] The disintegration value is the difference between the peak viscosity and the minimum viscosity, which reflects the thermal stability of starch paste and the degree of destruction of starch granules during gelatinization. Figure 2 As shown in the figure, like the peak viscosity, the disintegration value of corn flour first increases and then decreases as the ripening process proceeds. The disintegration values ​​of JD-15 and JD-25 first increase and then decrease, reaching the maximum at 40 days and 10 days, respectively. The disintegration values ​​of LY-15 and LY-25 also reach the maximum at 40 days and 10 days, indicating that the ripening process can enhance the shear resistance of corn flour.

[0074] The retrogradation value reflects the stability and aging trend of starch paste after cooling, which is related to the recrystallization of amylose. The retrogradation of starch paste will increase the hardness and toughness of starch gel. Figure 3 As shown in the figure, the retrogradation values ​​of the two varieties of corn at the two temperatures increased first and then decreased, increasing by 58.76%, 54.31%, 71.27% and 19.8% at 40 days (JD-15), 30 days (JD-25), 40 days (LY-15) and 30 days (LY-25), respectively. At 60 days, the retrogradation values ​​of JD-15 and LY-15 showed no significant difference compared with 0 days, while the retrogradation values ​​of JD-25 and LY-25 decreased by 9.12% and 27.64%, respectively. Appropriate post-ripening makes corn flour easier to retrograde, and the retrogradation value is not only related to the content of amylose, but also affected by the distribution of branches in amylopectin.

[0075] ②Texture characteristics of corn flour gel during post-ripening

[0076] The hardness of the gelatinized corn flour changes significantly during the post-ripening process ( Figure 4 ). As the ripening process progressed, the gel hardness of corn flour of the two varieties at both temperatures showed a pattern of first decreasing and then increasing, and the gel hardness of JD66 variety was significantly higher than that of LY99. At 60 days of ripening, the gel hardness of JD-15 and JD-25 increased by 23.79% and 29.30%; the gel hardness of LY-15 and LY-25 increased by 2.04 and 1.48 times.

[0077] During the ripening process, the gelatinized elasticity of corn flour of JD-15 and JD-25 increased slightly during 10-20 days and then decreased and stabilized ( Figure 5 ). The gelatinized corn flour elasticity of LY-15 and LY-25 decreased first and then stabilized. At 60 days, the gel elasticity of JD-15, JD-25, LY-15 and LY-25 decreased by 4.21%, 3.16%, 7.83% and 8.82%, respectively.

[0078] The chewiness changes significantly increased in the early stage of ripening and then decreased ( Figure 6 ). JD-15 and LY-25 increased by 84.35% and 30.02% in 0-30 days, and decreased by 3.20% and 31.31% in 30-60 days. JD-25 and LY-15 increased by 93.30% and 15.89% in 20 days and 10 days, respectively, and then decreased by 29.46% and 30.22% in 60 days.

[0079] The cohesiveness of both varieties of corn flour after gelatinization at both temperatures increased significantly between 10 and 20 days ( Figure 7 ). JD-15 and JD-25 reached their maximum values ​​at 10 days, and then changed little. After 60 days of ripening, the cohesion of corn flour samples increased by 31.78% and 29.20%, respectively. LY-15 and LY-25 increased by 54.05% and 57.70% at 20 days and 10 days, respectively, and then decreased after reaching the maximum. At 60 days, they increased by 25.33% and 22.72% of 0 days, respectively. The change of corn flour gel texture is related to the content and structure of starch in corn flour on the one hand, and the content of other substances such as protein and fat in corn flour during the ripening process on the other hand.

[0080] ③ Rheological properties of corn flour during post-ripening

[0081] The static rheological curves of corn starch at different ripening stages are as follows: Figure 8-9As shown. For the two varieties of corn flour at two temperatures, as the shear rate increases, the shear stress of all samples gradually increases. At the same shear rate, after post-ripening, the shear stress required by the system basically shows a pattern of first increasing and then decreasing, indicating that the hydrogen bonding between amylose-amylose and amylopectin-amylopectin inside the starch molecules gradually increases. Under the action of shear force, the hydrogen bonds between starch molecules break, causing changes in their gel structure. When the shear rate decreases or even disappears, the structure of the system will slowly recover, but the recovery speed is very slow, so a hysteresis phenomenon occurs, which manifests as thixotropy. The area of ​​the thixotropic ring first increases and then decreases with the post-ripening time, indicating that the damage to the gel network of corn flour caused by shear strain first increases and then decreases during the post-ripening process.

[0082] The relevant parameters obtained by fitting and analyzing the rheological data of two varieties of corn flour at two temperatures during the ripening process are shown in Table 1. As can be seen from the table, the regression fitting has a high accuracy (R 2 =0.98072-0.99931). The fluid index n of all samples is less than 1, indicating that the corn flour gel exhibits shear thinning behavior, which is a characteristic of pseudoplastic fluid. The consistency coefficient K represents the consistency of the system. The larger the K value, the better the thickening effect. As the ripening time progresses, the K value of the two varieties of corn flour in the ripening process at two temperatures reaches the maximum at 30 days, indicating that the moderate ripening process increases the consistency of the corn flour system.

[0083] Table 1 Changes in static rheological power law fitting parameters of corn flour during post-ripening

[0084]

[0085]

[0086] Dynamic rheological curves of corn flour at different ripening stages Figure 10-13 As shown. The G' and G" values ​​represent the elastic and viscous components of the samples, respectively. The G' of all samples gradually increased with the increase of frequency, while the G" first increased and then decreased with the increase of frequency, and the G" value was much lower than the corresponding G' value, indicating that the corn flour gel was elastic. After ripening, the G' and G" of JD-15, JD-25, LY-15 and LY-25 showed a pattern of first increasing and then decreasing. Our previous studies have shown that with ripening, the amylose content of corn starch first decreases and then increases. This may be due to the decrease in amylose content and the enhancement of the ability to form gel. On the other hand, it may also be because the ripening process promotes the entanglement and interaction of starch molecular chains, such as helical structure and crystal structure, thereby forming a strong gel network structure.

[0087] ④ Rheological properties of corn flour during post-ripening

[0088] The changes in RDS, SDS and RS content of corn flour of two varieties of corn during 60 days of ripening at 15℃ and 25℃ are shown in Table 2. Within 60 days after corn harvest, the RDS of corn flour at 15℃ and 25℃ first decreased slightly and then increased. The RDS in corn flour samples of JD-15, JD-25, LY-15 and LY-25 increased by 17.05%, 16.24%, 15.95% and 15.93%, respectively, and RS decreased by 17.73%, 24.35%, 25.23% and 24.57%, respectively. The chain length of long amylose branches, the ratio of long branches to short branches, and the order of starch will affect the digestibility of starch. In addition, substances such as protein, fat, and dietary fiber in corn flour will also affect the digestibility of corn flour.

[0089] Table 2 Changes in digestibility parameters of corn flour during post-ripening

[0090]

[0091]

[0092] Different letters in the same column indicate significant differences (p<0.05).

[0093] (4) SPSS21 software was used to perform principal component analysis on the above processing characteristics and digestion characteristics;

[0094] The original data of 11 indicators of processing and digestibility characteristics of corn flour of two varieties of corn ripened for 60 days under two temperature conditions were standardized using SPSS21 software, and the results are shown in Table 3. The data after standardization were subjected to principal component analysis. The principal component contribution rate and eigenvector of each indicator in the corn ripening process were analyzed. The KMO was 0.560>0.5, and the significance was 0.000. The eigenvalues ​​and eigenvectors obtained by principal component analysis are shown in Tables 4 and 5. The cumulative contribution rate of the first four principal components of the eigenvalue was 89.67%, which met the requirements of the principal component analysis method. The change trend of these four principal components can be used to replace the change trend of the overall data. The four principal components are named Z1, Z2, Z3, and Z4 respectively.

[0095] Table 3 Standardized results of various indicators of processing and digestibility of corn flour during post-ripening

[0096]

[0097]

[0098] JD / LY means the corn variety is JD66 or LY99; 15 / 25 means the ripening temperature is 15 or 25℃; 0-60 means the ripening days are 0-60 days.

[0099] Table 4 Principal component analysis eigenvalues ​​of various indicators of processing and digestibility of corn flour during post-ripening

[0100] principal component Initial eigenvalues Contribution rate (%) Cumulative contribution rate (%) 1 3.951 35.915 35.915 2 3.106 28.239 64.154 3 1.745 15.868 80.022 4 1.061 9.648 89.670 5 0.527 4.792 94.462 6 0.311 2.828 97.291 7 0.134 1.220 98.510 8 0.093 0.843 99.353 9 0.048 0.436 99.789 10 0.023 0.211 100 11 2.03E-08 1.84E-07 100

[0101] Table 5 Principal component analysis eigenvectors of various indicators of processing and digestibility of corn flour during post-ripening

[0102] index Ingredient 1 Ingredient 2 Ingredient 3 Ingredient 4 Peak viscosity 0.875 0.427 0.001 -0.062 Disintegration value 0.926 0.144 0.045 -0.104 Regeneration value 0.958 0.203 0.089 -0.045 hardness -0.382 0.823 -0.167 0.199 elasticity 0.342 -0.608 -0.29 0.536 Chewability 0.049 0.756 0.179 0.173 Cohesion -0.013 -0.35 0.655 -0.618 Thixotropic ring area 0.887 0.404 0.014 0.029 RDS -0.474 0.794 -0.042 -0.151 SDS 0.146 -0.347 0.794 0.449 RS 0.332 -0.456 -0.728 -0.285

[0103] The results of principal component analysis on the time-varying data of 11 indicators in the corn ripening process show that the four principal components retain the main information of the changes in corn flour processing and digestion quality during the corn ripening process. Four variables can be used to replace the original 11 indicators to measure the quality of corn flour during the corn ripening process.

[0104] (5) SPSS21 software was used to derive the linear equations of Z1, Z2, Z3, Z4 and the processing characteristics and digestion characteristics.

[0105] Z1=0.482×Z 回生值 +0.466×Z 崩解值 +0.446×Z 触变环面积 +0.440×Z 峰值黏度 -0.192×Z 硬度

[0106] -0.238×Z RDS +0.025×Z 咀嚼性 +0.172×Z 弹性 +0.073×Z SDS +0.167×Z RS -0.007×Z 内聚性 ;

[0107] Z2=0.115×Z 回生值 +0.082×Z 崩解值 +0.229×Z 触变环面积 +0.242×Z 峰值黏度 +0.467×Z 硬度

[0108] +0.451×Z RDS +0.429×Z 咀嚼性 -0.345×Z 弹性 -0.197×Z SDS -0.259×Z RS-0.199×Z 内聚性 ;

[0109] Z3=0.067×Z 回生值 +0.034×Z 崩解值 +0.011×Z 触变环面积 +0.001×Z 峰值黏度 -0.126×Z 硬度

[0110] -0.032×Z RDS +0.135×Z 咀嚼性 -0.219×Z 弹性 +0.601×Z SDS -0.551×Z RS +0.496×Z 内聚性 ;

[0111] Z4=-0.044×Z 回生值 -0.101×Z 崩解值 +0.028×Z 触变环面积 -0.060×Z 峰值黏度 +0.193×Z 硬度

[0112] -0.146×Z RDS +0.168×Z 咀嚼性 +0.52×Z 弹性 +0.435×Z SDS -0.276×Z RS -0.599×Z 内聚性 .

[0113] The variance contribution rates a1, a2, a3, and a4 of the principal components Z1, Z2, Z3, and Z4 are used as weights to construct the evaluation model: Z = 0.35915×Z1+0.28239×Z2+0.15868×Z3+0.09648×Z4.

[0114] The calculated Z1, Z2, Z3, and Z4 were respectively introduced into the evaluation model to obtain the Z values ​​under two storage conditions of ripening temperatures, and the results are shown in Table 6. The highest scores of JD66 and LY99 in the comprehensive evaluation of ripening quality at 15℃ and 25℃ were 1.3103 (JD66-15℃-40 days), 1.5415 (JD66-25℃-30 days), -0.2751 (LY99-15℃-40 days), and -0.5224 (LY99-15℃-30 days), respectively. The scores of JD66 varieties were generally higher than those of LY99. It can be considered that the ripening quality of JD66 is higher than that of LY99 under this model. Therefore, the optimal ripening conditions are 15℃-40 days and 25℃-30 days.

[0115] Table 6 Comprehensive component scores of processing and digestibility properties of corn flour during post-ripening

[0116]

[0117] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for constructing a comprehensive quality evaluation model for corn after-ripening, characterized in that: The method: (1) Select freshly harvested corn cobs with full kernels and store them in constant temperature and humidity chambers at 15°C and 25°C for 0 to 60 days respectively; (2) taking samples every 10 days, threshing, freeze-drying, crushing, and sieving to obtain cooked corn flour; (3) Analyze the processing characteristics and digestibility of corn flour. The processing characteristics include gelatinization, texture and rheological properties, and the digestibility characteristics include RDS, SDS and RS contents; (4) SPSS21 software was used to perform principal component analysis on the above-mentioned processing characteristics and digestion characteristics. During the principal component analysis, the original data of the processing characteristics and digestion characteristics were first standardized using SPSS21 software, and then the standardized data were subjected to principal component analysis to analyze the principal component contribution rate of each indicator. The change trend of the top four principal components in terms of contribution rate was used to replace the change trend of the overall data. The top four principal components were named Z1, Z2, Z3, and Z4, respectively. (5) SPSS21 software was used to derive the linear equations of Z1, Z2, Z3, Z4 and the processing characteristics and digestion characteristics. The variance contribution rates a1, a2, a3, a4 of the principal components Z1, Z2, Z3, Z4 were used as weights to construct the evaluation model.

2. The method according to claim 1, characterized in that In step (1), the humidity is 50-60%.

3. The method according to claim 2, characterized in that The humidity in step (1) is 55%.

4. The method according to claim 1, characterized in that: The processing characteristics in step (3) include peak viscosity, disintegration value, regeneration value, thixotropic ring area of ​​static rheology, gel hardness, gel elasticity, cohesion, and chewiness.

5. The method according to claim 1, characterized in that The linear equations of Z1, Z2, Z3, and Z4 in step (4) are: Z1=0.482×Z 回生值 +0.466×Z 崩解值 +0.446×Z 触变环面积 +0.440×Z 峰值黏度 -0.192×Z 硬度 -0.238×Z RDS +0.025×Z 咀嚼性 +0.172×Z 弹性 +0.073×Z SDS +0.167×Z RS -0.007×Z 内聚性 ; Z2=0.115×Z 回生值 +0.082×Z 崩解值 +0.229×Z 触变环面积 +0.242×Z 峰值黏度 +0.467×Z 硬度 +0.451×Z RDS +0.429×Z 咀嚼性 -0.345×Z 弹性 -0.197×Z SDS -0.259×Z RS -0.199×Z 内聚性 ; Z3=0.067×Z 回生值 +0.034×Z 崩解值 +0.011×Z 触变环面积 +0.001×Z 峰值黏度 -0.126×Z 硬度 -0.032×Z RDS +0.135×Z 咀嚼性 -0.219×Z 弹性 +0.601×Z SDS -0.551×Z RS +0.496×Z 内聚性 ; Z4=-0.044×Z 回生值 -0.101×Z 崩解值 +0.028×Z 触变环面积 -0.060×Z 峰值黏度 +0.193×Z 硬度 -0.146×Z RDS +0.168×Z 咀嚼性 +0.52×Z 弹性 +0.435×Z SDS -0.276×Z RS -0.599×Z 内聚性 。 6. The method according to claim 1, characterized in that The evaluation model in step (4) is: comprehensive quality Z = a1Z1+a2Z2+a3Z3+a4Z4.

7. Use of the method according to any one of claims 1 to 6 in screening corn ripening conditions.

8. A method for preparing post-ripened corn flour with high processing and digestion properties determined by the method described in any one of claims 1 to 6, characterized in that: The method: Newly harvested corn cobs with full grains are selected, placed in a constant temperature and humidity box at 15-25° C. and 50-60% relative humidity for storage for 30-40 days, and then threshed, freeze-dried, crushed, and sieved to obtain ripened corn flour.

9. The cooked corn flour with high processing and digestion properties obtained by the method of claim 8.

10. Use of the ripened corn flour with high processing and digestion properties as claimed in claim 9 in the food field.

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