An evaluation method for the freshness of non-uniform high-starch yam bean paste food

Abstract

The present invention discloses a method for evaluating the freshness of non-uniform high-starch yam paste foods. The solid-liquid two phases of the paste food are separated by centrifugation, and the OD value and color chromatic aberration are used as detection indexes. The freshness of non-uniform high-starch yam paste foods is evaluated in the form of a mathematical simulation equation, and a multiple linear regression equation for evaluating the freshness of non-uniform high-starch yam paste foods is proposed: Y = 46.159 - 37.1997*X OD值 + 0.9323*X ΔE + 0.4013*X L* , R 2 = 0.9868; The present invention solves the blank in the evaluation of related aspects and has reference significance for subsequent related evaluation methods. It does not require operators with special professional training, has high accuracy and small errors.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the freshness of non-uniform high-starch yam-based paste foods in the food field. A mathematical simulation equation for evaluating the freshness of non-uniform high-starch yam-based paste foods is constructed from two aspects: the liquid optical density value and the solid color difference, thereby providing a new method for identifying its freshness. Background Art

[0002] Color difference evaluation has been applied for a long time in related industrial fields such as textile printing and dyeing, pulp and paper making, and paint coatings at home and abroad. A color difference meter is the most commonly used color detection instrument at present. According to different principles, color difference meters can be divided into photoelectric integrating color difference meters and spectrophotometric color difference meters. The photoelectric integrating color difference meter can quickly and accurately measure the color of the sample site to be tested, and can directly convert it into L * , a * , b * values or X, Y, Z values. The spectrophotometric color difference meter is based on the principle of spectroscopy. It can measure the spectral distribution of an object and calculate the tristimulus values and other parameters. In the domestic research on food quality evaluation, due to the advantages of quickness and non-destructiveness of the color difference meter, it is widely used in fruits and vegetables, meat products, grains, etc. The spectrophotometry is a method for qualitative and quantitative analysis of a substance by measuring the absorbance of the substance at a specific wavelength or within a certain wavelength range. It has the advantages of high sensitivity, simple operation, and rapidity.

[0003] The aging of starch refers to the process in which the gelatinized starch molecules transform from a disordered state to an ordered state. After the starch ages, the color of the product will change. For the food color tone changes of non-uniform high-starch yam-based paste foods with natural colors such as carotenoids or anthocyanins, it is impossible to evaluate their intuitive sensory acceptance degree. It is also impossible to detect the degree of color tone change caused by the aging of starch gel only based on the color change. Using sensory evaluation for the color evaluation of products requires professional trained personnel, takes a long time, and cannot achieve a unified score, and it is impossible to effectively determine the freshness of products within the shelf life. Summary of the Invention

[0004] Aiming at the current situation of no effective means to evaluate the freshness of non-uniform high-starch yam-based paste foods, the present invention constructs a mathematical simulation equation for evaluating the freshness of non-uniform high-starch paste foods from two aspects: the optical density value and the color difference, thereby providing a new method for identifying its freshness.

[0005] The present invention takes mung bean puree as the analysis object. After centrifugation, the supernatant is taken to remove proteins and fats. After quickly adsorbing pigments with activated carbon, filtration is carried out. α-Amylase is used to hydrolyze its starch. Since retrograded starch has anti-enzyme properties and is less susceptible to hydrolysis, KI-I2 is then added, and the absorbance is measured at 620 nm. As time increases, the absorbance shows an upward trend. The lower-layer solid after centrifugation is measured for its surface chromaticity and color difference (ΔE, L*, a*, b*) using a color difference meter. With the ratio of gelatinization degree / retrogradation degree as the evaluation index, a multiple linear regression equation is constructed through correlation analysis to evaluate the freshness of non-uniform high-starch leguminous and tuberous paste foods.

[0006] The technical solution of the present invention is as follows:

[0007] A method for evaluating the freshness of non-uniform high-starch leguminous and tuberous paste foods, comprising the following steps:

[0008] Step 1: Preparation of mung bean puree

[0009] Take steamed mung beans, add emulsion, and obtain mung bean puree after beating, filling, and sterilization;

[0010] The emulsion is prepared by mixing water, coconut oil, and an emulsion stabilizer; wherein, the emulsion stabilizer is composed of konjac gum, xanthan gum, and molecular distilled monoglyceride with a mass ratio of 1:2-10:5-10; the volume-mass ratio of water to konjac gum is 30-50:1 mL / g; the mass ratio of water to coconut oil is 3-5:1;

[0011] The volume-mass ratio of the emulsion to mung beans is 1.5-2:1 mL / g;

[0012] The mung bean puree is a non-uniform paste with a certain fluidity;

[0013] Step 2: Centrifugation

[0014] Centrifuge the prepared mung bean puree to obtain the upper-layer supernatant and the lower-layer solid respectively;

[0015] The conditions for centrifugation are 4°C, 9000 rpm, and 10 min;

[0016] Step 3: Measurement of absorbance

[0017] Absorb the supernatant, first perform degreasing, deproteinization, and decolorization treatments, then take 5 mL of the supernatant, add 2 mL of 0.1 N phosphate buffer (pH 5.6) and 0.02 mL of 10000 u / mL α-amylase solution, react at 60 - 100 °C for 10 min, then add 5 mL of 4 N NaOH solution to stop the enzyme reaction, adjust the pH to 6 - 9 after cooling to room temperature, and make up the volume to 100 mL to obtain a hydrolyzate; take 5 mL of the hydrolyzate, add 0.2% I2 - 2% KI solution, let it stand for 10 min, dilute to 100 mL, and then measure the absorbance (OD value) at 620 nm using an ultraviolet spectrophotometer;

[0018] Step 4: Determination of chromaticity and color difference

[0019] Take the centrifuged solid, analyze it using a color difference meter, measure the chromaticity values of the object under standard D65 and C light sources, select the data of the CIE1964 supplementary observer at a 10° viewing angle, the illumination geometry condition of the instrument is o / d, and the observation conforms to the 0° incidence / 45° reception condition specified by CIE. The spectral condition should make the overall response equivalent to the tristimulus values under the CIE standard illuminant D65 and the 10° field-of-view color matching function. Finally, its surface chromaticity (L*, a*, b*) and color difference ΔE =

(ΔL*) 2 +(Δa*) 2 +(Δb*) 2

[0020] Step 5: Determination of retrograded starch content

[0021] Determine the retrogradation degree of mung bean paste, calculate the ratio of gelatinization degree to retrogradation degree, gelatinization degree / retrogradation degree (%) = (1 - retrogradation degree) / retrogradation degree * 100;

[0022] The method for determining the retrogradation degree of starch can adopt the method of Jin Zhengyu (ZL 101839852A) et al. Determine the retrogradation degrees of mung bean paste samples on the 0th day, 30th day, and during the storage period respectively. The specific operation is as follows:

[0023] After vacuum freeze-drying the mung bean paste, pulverize it through an 80-mesh sieve, weigh 50 mg of the pulverized sample, disperse it in 5 mL of 0.01 N sodium hydroxide solution, and then neutralize it to neutral with 0.01 N dilute hydrochloric acid; take 5 mL of this dispersion, add 3 mL of 0.2% I2 - 2% KI solution and 5 mL of pH 4.0 acetic acid - sodium acetate buffer, make up the volume to 50 mL, measure the absorbance at 600 nm after reacting for 15 min, and calculate the retrogradation degree (%) according to the absorbance: X t =(A0 - A t ) / (A0 - A ∞ ) * 100;

[0024] Among them, X t is the retrogradation degree of the product after storage for t time; A0 is the absorbance of the product stored for 0 days; A t is the absorbance of the product stored for t days; A ∞ is the limiting absorbance of the product stored for 30 days;

[0025] Step 6: Correlation analysis

[0026] Using the DPS data processing system, selecting grey relational analysis, with the resolution coefficient set to 0.5, screening the influencing total chromaticity index, and finally determining that the sensitivity indexes of total chromaticity are L* (brightness), ΔE (color difference), and the OD value after enzymatic hydrolysis;

[0027]

[0028] Step 7: Construction of multiple linear regression equation

[0029] According to the results of the correlation analysis, further perform multiple linear regression analysis to establish a mathematical model, and obtain a mathematical simulation equation for evaluating the freshness of non-uniform high-starch yam bean paste food:

[0030] Y = 46.159 - 37.1997*X OD值 + 0.9323*X ΔE + 0.4013*X L* , R 2 = 0.9868

[0031] When detecting actual samples, only need to measure their OD values, chromaticity, and color difference, substitute them into the mathematical simulation equation, and then the gelatinization degree / retrogradation degree (%) can be obtained to complete the evaluation.

[0032]

[0033] Analysis of variance

[0034]

[0035]

[0036] The beneficial effects of the present invention are as follows:

[0037] The present invention proposes a method for evaluating the freshness of non-uniform high-starch paste food, solves the blank in relevant evaluations, has reference significance for subsequent relevant evaluation methods, and does not require operators with special professional training, with high accuracy and small errors.

[0038] The present invention uses centrifugation to separate the solid and liquid phases of pasty foods, and takes their OD values and chromaticity color differences as detection indexes. It evaluates the freshness of non-uniform high-starch yam and sweet potato pasty foods in the form of a mathematical simulation equation, and proposes a multiple linear regression equation for evaluating the freshness of non-uniform high-starch yam and sweet potato pasty foods: Y = 46.159 - 37.1997*X DD值 + 0.9323*X AE + 0.4013*X L＊ , R 2 = 0.9868

[0039] According to the evaluation method of the present invention, the freshness of related foods can be better judged. During this period, only several conventional detection indexes such as its OD 620 and chromaticity and color difference need to be measured to complete the evaluation. Its accuracy is higher than 85%, and it has the characteristics of convenient operation, easy implementation, and fast, accurate and efficient evaluation, making up for the blank in the related field and providing a new idea for evaluating the freshness of non-uniform high-starch yam and sweet potato pasty foods Detailed implementation method

[0040] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present invention belongs

[0041] Example 1

[0042] 1. Measure the retrogradation degree of mung bean paste after storage for 3 days, 6 days, and 9 days respectively:

[0043] Measure the retrogradation degree of the samples on the 0th day, the 30th day, and after storage for 3 days, 6 days, and 9 days respectively. The specific operation: After the mung bean paste is completely vacuum freeze-dried, it is ground through an 80-mesh sieve. Weigh 50 mg of the ground sample, disperse it in 5 ml of 0.01N sodium hydroxide solution, and after dissolution, neutralize it to neutral with 0.01N dilute hydrochloric acid. Take 5 ml of this dispersion, add 3 ml of 0.2% I2 - 2% KI, add 5 ml of pH 4.0 acetic acid-sodium acetate buffer solution, and make up the volume to 50 ml. React for 15 minutes and measure the absorbance at 600 nm. Calculate the retrogradation degree (%) X according to the absorbance t =(A0 - A t ) / (A0 - A∞)*100;

[0044] Among them, Xt is the retrogradation degree of the product after storage for t time; A0 is the absorbance of the product stored for 0 days; A t is the absorbance of the product stored for t days; A∞ is the limiting absorbance of the product stored for 30 days

[0045] Calculate the ratio of gelatinization degree to retrogradation degree:

[0046] Gelatinization degree / regeneration degree (%) = (1-regeneration degree) / regeneration degree*100

[0047] 2. Centrifugation:

[0048] The three groups of mung bean pastes were centrifuged in a centrifuge at 4°C and 9000 rpm for 10 min respectively.

[0049] 3. Determination of absorbance:

[0050] 8 mL of the upper clear liquid was taken, and 2 mL of ether-petroleum ether with a volume ratio of 1:1 was added for degreasing treatment, and then 0.5 g of neutral lead acetate was added and mixed, and the mixture was allowed to stand for 30 min. After filtration and centrifugation, 0.2 g of microporous activated carbon was added and the mixture was allowed to stand for 5 min. After removing the pigment, 5 ml of the filtrate was taken, 2 ml of 0.1 N phosphate buffer (pH 5.6) and 0.02 ml of α-amylase solution (10000u / ml) were added, and the mixture was reacted at 80°C for 10 min. Then 5 ml of 4N NaOH was added to stop the enzyme reaction, and the pH was adjusted to 7 after cooling, and the volume was adjusted to 100 ml. 5 ml of the hydrolyzate was taken, and 0.2% I2-2% KI solution was added, and the mixture was allowed to stand for 10 min, and the volume was diluted to 100 ml. Then, the absorbance was measured at 620 nm using a UV spectrophotometer.

[0051] 4. Determination of chromaticity and color difference:

[0052] Take the solid after centrifugation and use a colorimeter to analyze it. Measure the chromaticity value of the object under standard D65 and C light sources. Use CIE1964 to supplement the data of the observer's 10° viewing angle. The instrument lighting geometry condition is o / d. The observation meets the 0° incidence / 45° reception conditions specified by CIE. The spectral condition should make the overall response equivalent to the tristimulus values ​​under the CIE standard illuminant D65 and 10 field of view color matching function. Finally, its surface chromaticity (L*, a*, b*) and color difference ΔE=

(ΔL*) 2 +(Δa*) 2 +(Δb*) 2

[0053] 5. Equation Verification

[0054] The gelatinization degree / regeneration degree (%), ΔE, L*, and OD of mung bean paste stored for 3, 6, and 9 days 620 After analysis, it was found that it conforms to Y = 46.159-37.1997*X OD620 +0.9323*X ΔE +0.4013*X L* , R 2= 0.9868.

[0055]

[0056] According to the freshness evaluation method of the present invention, the freshness of related foods can be better judged. During this period, only several conventional detection indexes such as its OD 620 and chromaticity and color difference need to be measured to complete the evaluation, which has the characteristics of convenient operation, easy implementation, fast, accurate and efficient evaluation.

Claims

1. A method for evaluating the freshness of non-uniform high-starch yam-based paste foods, characterized in that, It includes the following steps: Step 1: Preparation of mung bean puree Take the steamed mung beans, add emulsion, and obtain mung bean puree after pulping, filling, and sterilization; Step 2: Centrifugation Centrifuge the prepared mung bean puree to obtain the upper clear liquid and the lower solid respectively; Step 3: Determination of absorbance Absorb the upper clear liquid, first perform degreasing, deproteinization, and decolorization treatments, then take 5 mL of the clear liquid, add 2 mL of 0.1N phosphate buffer and 0.02 mL of 10000 u / mL α-amylase solution, react at 60-100 °C for 10 min, then add 5 mL of 4N NaOH solution to stop the enzyme reaction, adjust the pH to 6-9 after cooling to room temperature, and make up the volume to 100 mL to obtain the hydrolysis solution; Take 5 mL of the hydrolysis solution, add 0.2% I2-2% KI solution, let it stand for 10 min, dilute it to 100 mL, and then use an ultraviolet spectrophotometer to measure the absorbance (OD value) at 620 nm; Step 4: Determination of chromaticity and color difference Take the centrifuged solid and analyze it using a color difference meter. Measure the chromaticity values of the object under standard D65 and C light sources. Select the data of the CIE1964 supplementary observer at a 10° viewing angle. The illumination geometry condition of the instrument is o / d, and the observation conforms to the 0° incidence / 45° reception condition specified by the CIE. The spectral condition should make the overall response equivalent to the tristimulus values under the CIE standard illuminant D65 and the 10° field-of-view color matching function. Finally, its surface chromaticity (L*, a*, b*) and color difference ΔE = 【(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 】 0.5 ; Step 5: Determination of retrograded starch content Determine the degree of starch retrogradation of the mung bean puree, calculate the ratio of gelatinization degree to retrogradation degree, gelatinization degree / retrogradation degree (%) = (1 - retrogradation degree) / retrogradation degree * 100; Step 6: Correlation analysis Use the DPS data processing system, select grey relational analysis, set the resolution coefficient to 0.5, screen the indicators affecting the total chromaticity index, and finally determine the sensitivity indicators of the total chromaticity as L* (brightness), ΔE (color difference), and OD value after enzymatic hydrolysis; Step 7: Construction of multiple linear regression equation According to the results of the correlation analysis, perform multiple linear regression analysis on the gelatinization degree / retrogradation degree (%), ΔE, L*, and OD value of the mung bean puree to establish a mathematical model, and obtain a mathematical simulation equation for evaluating the freshness of non-uniform high-starch leguminous and tuberous paste foods: Y = 46.159 - 37.1997*X OD值 + 0.9323*X ΔE + 0.4013*X L* , R 2 = 0.9868 When detecting actual samples, only need to measure its OD value, chromaticity, and color difference, substitute them into the mathematical simulation equation, and the gelatinization degree / retrogradation degree (%) can be obtained to complete the evaluation.

2. The method for evaluating the freshness of non-uniform high-starch yam-based paste foods according to claim 1, characterized in that, In Step 1, the emulsion is prepared by mixing water, coconut oil, and an emulsion stabilizer; among them, the emulsion stabilizer is composed of konjac gum, xanthan gum, and molecular distilled monoglyceride with a mass ratio of 1:2-10:5-10; the volume-mass ratio of water to konjac gum is 30-50:1 mL / g; the mass ratio of water to coconut oil is 3-5:

1.

3. The method for evaluating the freshness of non-uniform high-starch yam-based paste foods according to claim 1, characterized in that, In Step 1, the volume-mass ratio of the emulsion to mung beans is 1.5-2:1 mL / g.

4. The method for evaluating the freshness of non-uniform high-starch yam-based paste foods according to claim 1, characterized in that, In Step 2, the conditions for centrifugation are 4 °C, 9000 rpm, and 10 min.

5. The method for evaluating the freshness of non-uniform high-starch yam-based paste foods according to claim 1, characterized in that, In Step 5, the method for determining the degree of starch retrogradation is as follows: Vacuum freeze-dry the mung bean puree, crush it through an 80-mesh sieve, weigh 50 mg of the crushed sample, disperse it in 5 mL of 0.01N sodium hydroxide solution, and then neutralize it to neutral with 0.01N dilute hydrochloric acid; Take 5 mL of the dispersion, add 3 mL of 0.2% I2 - 2% KI solution and 5 mL of pH 4.0 acetic acid - sodium acetate buffer solution, make up the volume to 50 mL, measure the absorbance at 600 nm after reacting for 15 min, and calculate the retrogradation degree (%) according to the absorbance: X t =(A0 - A t ) / (A0 - A ∞ ) * 100; Among them, X t is the retrogradation degree of the product after storing for t time; A0 is the absorbance of the product stored for 0 days; A t is the absorbance of the product stored for t days; A ∞ is the limiting absorbance of the product stored for 30 days.

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