Method for selecting ovomucoid-free shelled chicken eggs

Abstract

The present invention pertains to a method for selecting ovomucoid-free shelled chicken eggs, the method comprising: a measurement step for irradiating a shelled egg with light including light having a specific wavelength to measure the absorbed amount of the light having the specific wavelength; a calculation step for calculating a determination value by substituting the absorbed amount into a conversion formula; and a selection step for selecting an ovomucoid-free shelled chicken egg on the basis of the determination value. The conversion formula is derived from the result of measurement of the absorbed amount of the light having the specific wavelength with respect to ovomucoid-containing shelled chicken eggs and ovomucoid-free shelled chicken eggs.

Description

A method for selecting shell eggs that do not contain ovomucoid

[0001] The present invention relates to a method for selecting shell eggs that do not contain ovomucoid.

[0002] Various technical means have been proposed as methods for measuring components in chicken eggs. For example, Patent Document 1 discloses a method for determining shell eggs, comprising the steps of irradiating shell eggs with light, receiving light transmitted through the shell eggs, acquiring a spectrum of the transmitted light, performing multivariate analysis of the spectrum, and determining whether the shell eggs are shell eggs based on the spectrum. Furthermore, Patent Document 2 discloses that the cholesterol content in chicken eggs can be quantified with high accuracy without cracking them by irradiating eggs with near-infrared light in a specific wavelength range and detecting the transmitted light.

[0003] JP 2017-49177 A Japanese Patent No. 5959061 A

[0004] One of the known allergens in chicken eggs is a protein called ovomucoid, which is contained in egg white. Ovomucoid is stable to heat and digestive enzymes, so its allergenicity is not easily lost even when subjected to heat treatment and processing using digestive enzymes. For this reason, studies are underway to develop chicken eggs that do not contain ovomucoid.

[0005] On the other hand, ovomucoid in chicken eggs is generally measured, for example, by liquid chromatography, ELISA, or the like using egg white obtained by cracking eggs. However, such measurement methods are commercially unsuitable because the procedures are complicated and the eggs are cracked, limiting their applications. Therefore, there is a need for the development of a non-destructive and simple method for selecting shell eggs that do not contain ovomucoid.

[0006] An object of the present invention is to provide a method for non-destructively and simply selecting shell eggs that do not contain ovomucoid.

[0007] The inventors discovered that by irradiating shell eggs with light containing light of a specific wavelength, measuring the amount of light absorbed at that specific wavelength, and then calculating a discrimination value from the amount of absorption using a predetermined conversion formula, it is possible to determine whether or not a shell egg contains ovomucoid based on the discrimination value, and thus completed the present invention.

[0008] That is, the present invention relates to, for example, the following inventions. [1] A method for sorting shell eggs that do not contain ovomucoid, comprising: a measuring step of irradiating shell eggs with light containing a specific wavelength and measuring the amount of light absorbed at the specific wavelength; a calculating step of calculating a discriminant value by substituting the amount of absorption into a conversion formula; and a sorting step of sorting shell eggs that do not contain ovomucoid based on the discriminant value, wherein the conversion formula is a formula derived from the results of measuring the amount of light absorbed at the specific wavelength for shell eggs that contain ovomucoid and shell eggs that do not contain ovomucoid. [2] The sorting method according to [1], wherein the light at the specific wavelength is light that is within a wavelength range of 310 nm to 2500 nm. [3] The sorting method according to [1] or [2], wherein the conversion formula is a formula derived by partial least squares discriminant analysis. [4] The selection method according to any one of [1] to [3], wherein the transformation formula is an equation derived by partial least squares discriminant analysis, with a discrimination value of 1 for shell eggs containing ovomucoid and a discrimination value of 0 for shell eggs not containing ovomucoid, and the selection step selects shell eggs as not containing ovomucoid when the discrimination value calculated in the calculation step is less than a threshold value, the threshold value being within a range of more than 0 and not more than 0.6. [5] A method for producing ovomucoid-free shell eggs, comprising a step of carrying out the selection method according to any one of [1] to [4] to select shell eggs not containing ovomucoid.

[0009] According to the present invention, a method for non-destructively and simply selecting shell eggs that do not contain ovomucoid can be provided.

[0010] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0011] (Method for sorting shell eggs that do not contain ovomucoid) The present invention is characterized by providing a method for sorting shell eggs that do not contain ovomucoid, comprising a measurement step of irradiating shell eggs with light containing light of a specific wavelength and measuring the amount of light absorbed at the specific wavelength; a calculation step of calculating a discrimination value by substituting the amount of absorption into a conversion formula; and a sorting step of sorting shell eggs that do not contain ovomucoid based on the discrimination value, wherein the conversion formula is a formula derived from the results of measuring the amount of light absorbed at the specific wavelength for shell eggs that contain ovomucoid and shell eggs that do not contain ovomucoid.

[0012] (Measurement Step) The method for sorting shell eggs that do not contain ovomucoid according to this embodiment includes a measurement step of irradiating the shell eggs with light containing light of a specific wavelength and measuring the amount of light absorbed at the specific wavelength.

[0013] (Shelled eggs) In this specification, "shelled eggs" refer to unbroken eggs that have all of the eggshell, egg yolk, and egg white. Shelled eggs may have cracked eggshells, etc., as long as they have all of the eggshell, egg yolk, and egg white. Shelled eggs can be those used as food materials, etc. There are no particular limitations on the breed of laying hens and / or the time of egg laying for shelled eggs. Furthermore, the shell of a shelled egg may be white, or may be colored, such as brown or reddish brown.

[0014] (Ovomucoid-free shell eggs) In this specification, "ovomucoid-free shell eggs" refer to shell eggs that do not contain ovomucoid, and are the same as those described above for shell eggs, except that they do not contain ovomucoid. Ovomucoid is a protein contained in egg white and is one of the allergens in eggs. Ovomucoid is also water-soluble and has extremely high physicochemical stability. Therefore, its allergenicity is not easily lost even when subjected to heat treatment and processing using digestive enzymes.

[0015] As used herein, "not containing ovomucoid" means that the ovomucoid content in the egg white is less than 1 μg / mL, preferably 0 μg / mL, based on the total amount of egg white.

[0016] (Uses of Ovomucoid-Free Shell Eggs) Uses of ovomucoid-free shell eggs include, for example, boiled eggs, confectionery, cooking, bread making, frozen desserts, water kneading, ham, noodles, etc. "For boiled eggs" means use as an ingredient for boiled eggs. "For confectionery" means use as an ingredient for producing confectionery. Ovomucoid-free shell eggs for confectionery can be used, for example, as an ingredient for sponge cakes, etc. "For cooking" means use as an ingredient for producing foods and beverages (excluding confectionery). Ovomucoid-free shell eggs for cooking can be used, for example, as an ingredient for scrambled eggs, egg soup, fried eggs, omelets, rolled eggs, etc. The method for selecting ovomucoid-free shell eggs according to this embodiment can also be used as a method for selecting ovomucoid-free shell eggs for boiled eggs, confectionery, or cooking. Furthermore, because ovomucoid is a protein that has allergenic properties, ovomucoid-free shell eggs can also be used to develop hypoallergenic foods. Hypoallergenic foods refer to foods that are unlikely to cause allergies.

[0017] Ovomucoid-free shell eggs may be distributed in the form of shell eggs, or may be distributed in the form of cracked eggs containing egg white and egg yolk, or may be distributed in the form of egg white or egg yolk after cracking and further separating the egg white and egg yolk.

[0018] (Method for measuring the amount of light absorption at a specific wavelength) The amount of light absorption at a specific wavelength (hereinafter also referred to as "absorption amount") is measured using spectroscopy, in which light containing light of a specific wavelength is irradiated onto a shell egg and the transmitted or reflected light is detected. That is, in the measurement step, the amount of absorption is measured by irradiating light containing light of a specific wavelength onto a shell egg and detecting the transmitted or reflected light. The amount of absorption measured may be an absolute value or a relative value (e.g., absorbance). Furthermore, the amount of absorption measured may be the amount of absorption of light of a single wavelength, or may be the amount of absorption of light of multiple wavelengths. When the amount of absorption measured is the amount of absorption of light of multiple wavelengths, it may be light of multiple continuous wavelengths or light of multiple discontinuous wavelengths. When the amount of absorption of light of multiple wavelengths is measured, for example, an absorption spectrum including the amount of absorption of light of specific wavelengths may be measured.

[0019] In the method for sorting ovomucoid-free shell eggs according to the present embodiment, it is preferable to measure the absorption amount by detecting transmitted or reflected light. The absorption amount can be measured, for example, using a visible-near infrared spectrophotometer, a near-infrared spectrophotometer, or the like. As a visible-near infrared spectrophotometer, for example, the Handy Lambda II NIR enh manufactured by SpectraCorp, Inc. can be used. As a near-infrared spectrophotometer, for example, the near-infrared spectrometer Matrix-F manufactured by Bruker Optics, Inc. can be used. The obtained absorption amount data can be analyzed using commercially available software. Examples of commercially available software include The Unscrambler X (manufactured by CAMO Software) and OPUS (manufactured by Bruker Optics, Inc.).

[0020] (Light of specific wavelength) The light of the specific wavelength used in the measurement step may be light within the wavelength range of, for example, 310 nm to 2500 nm, 310 nm to 2000 nm, 310 nm to 1500 nm, or 310 nm to 1100 nm, or 600 nm to 2500 nm, 800 nm to 2500 nm, or 1100 nm to 2500 nm. As described above, the light of the specific wavelength may be light within the above wavelength range, and may be light of a single wavelength within the above wavelength range, or light of multiple wavelengths within the above wavelength range. Since the amount of light of a wavelength within this wavelength range that is absorbed by shell eggs differs between shell eggs that do not contain ovomucoid and shell eggs that contain ovomucoid, it is possible to select shell eggs that do not contain ovomucoid based on the amount of absorption.

[0021] (Wavelength of Light Irradiated onto Shell Eggs) The light irradiated onto shell eggs in the measurement step (hereinafter also referred to as "irradiation light") is not particularly limited as long as it contains light of the specific wavelength. That is, the irradiation light may contain light of wavelengths other than the specific wavelength, or may be light of the specific wavelength. The absorption amount is measured by irradiating the shell eggs with irradiation light. The irradiation light may be, for example, light in the wavelength range of 100 nm to 3000 nm, 150 nm to 2500 nm, 200 nm to 2000 nm, 300 nm to 1500 nm, or 310 nm to 1100 nm, or 500 nm to 3000 nm, 600 nm to 3000 nm, 700 nm to 2800 nm, 750 nm to 2600 nm, or 800 nm to 2500 nm.

[0022] (Conditions for placing shell eggs) In the measurement step, the shell eggs may be placed, for example, so that the long axis connecting the blunt end and sharp end of the shell egg is parallel or approximately parallel to the horizontal plane, or so that the long axis is perpendicular or approximately perpendicular to the horizontal plane. When the long axis is perpendicular or approximately perpendicular to the horizontal plane, the shell eggs may be placed so that the blunt end faces downward. In the measurement step, the shell eggs may be fixed so that they are placed in the above-mentioned position.

[0023] (Irradiation conditions for light irradiated onto shell eggs) In the measurement step, the irradiated light can be applied to the shell eggs from various directions. The irradiated light can be applied while the shell eggs are fixed so that they are positioned as described above, or while they are not fixed. For example, the irradiated light can be applied in a direction intersecting the long axis connecting the blunt end and the sharp end of the shell eggs, or in a direction along the long axis. The absorption amount can be measured, for example, by irradiating the shell eggs in a direction intersecting the long axis connecting the blunt end and the sharp end of the shell eggs with light, with the blunt end of the shell eggs facing downward, with the long axis connecting the blunt end and the sharp end of the shell eggs perpendicular or perpendicular to the horizontal plane, with the irradiated light in a direction intersecting the long axis, and detecting the transmitted or reflected light. The absorption amount can also be measured, for example, by irradiating the shell eggs in a direction intersecting the long axis connecting the blunt end and the sharp end of the shell eggs with light, with the blunt end of the shell eggs facing downward, with the long axis connecting the blunt end and the sharp end of the shell eggs perpendicular or perpendicular to the horizontal plane, with the irradiated light in a direction intersecting the long axis, and detecting the transmitted or reflected light.

[0024] (Detection of light of a specific wavelength) When irradiating with irradiation light and detecting transmitted light, it is preferable to irradiate a portion of the egg that does not pass through the egg yolk and detect the transmitted light, from the viewpoint of enabling more accurate measurement. When irradiating with irradiation light and detecting reflected light, it is also possible to detect reflected light originating from the egg white portion of a shell egg.

[0025] (Calculation Step) The method for selecting shell eggs that do not contain ovomucoid includes a calculation step of calculating a discrimination value by substituting the absorption amount into a conversion formula.

[0026] (Conversion Formula) In the calculation step, the conversion formula is used to calculate a discriminant value from the absorption amount measured in the measurement step. The conversion formula is a formula derived from the results of measuring the absorption amount for shell eggs containing ovomucoid and shell eggs not containing ovomucoid. More specifically, it is a relational formula between the absorption amount and the discriminant value derived using the measured absorption amount as an explanatory variable and the discriminant value as a response variable. The conversion formula may be, for example, a formula derived by multivariate analysis, or a formula derived by partial least squares discriminant analysis (PLS-DA), logistic regression analysis, or the like, and is preferably a formula derived by partial least squares discriminant analysis. The discriminant value is a numerical value set by associating a predetermined numerical value with each of shell eggs containing ovomucoid and shell eggs not containing ovomucoid, and is a numerical value for discriminating between shell eggs not containing ovomucoid. For example, shell eggs containing ovomucoid may be associated with numerical values, with the discrimination value being 1 and shell eggs not containing ovomucoid being associated with numerical values. In this case, the conversion formula may be derived by partial least squares discriminant analysis from the results of measuring the absorption amounts, with the discrimination value being 1 for shell eggs containing ovomucoid and the discrimination value being 0 for shell eggs not containing ovomucoid.

[0027] (Multivariate Analysis) Multivariate analysis is a statistical technique used to classify subjects by simultaneously analyzing multiple data (variables) obtained from the subject, to analyze the interrelationships between multiple data, and to comprehensively summarize multiple data. Multivariate analysis may be performed in combination with a spectral filtering method, such as orthogonal signal correction (OSC), to remove interfering components, as needed. Many analytical tools are commercially available as software, and any one can be obtained. Such commercially available tools generally come with an operating manual so that multivariate analysis can be performed without knowledge of difficult mathematics or statistics. Multivariate analysis may be performed using some or all of the obtained analytical data.

[0028] (Partial Least Squares Discriminant Analysis (PLS-DA)) PLS-DA is a method of constructing a model for discriminating between two groups by applying partial least squares (PLS) to discriminant analysis (DA). In the method for selecting ovomucoid-free shell eggs according to this embodiment, a model (transformation formula) is constructed that discriminates between shell eggs containing ovomucoid and shell eggs not containing ovomucoid based on the absorption amount measured above.

[0029] (Shell eggs containing ovomucoid in the calculation step) Shell eggs containing ovomucoid in the calculation step are used to derive the conversion formula. The ovomucoid-containing shell eggs are as described above for shell eggs, except that they contain ovomucoid. Examples of shell eggs containing ovomucoid in the calculation step include shell eggs obtained from laying hens of wild-type chicken breeds. The ovomucoid-containing shell eggs in the calculation step may be shell eggs known to be ovomucoid-containing shell eggs when the absorption amount of light of the specific wavelength is measured, or may be shell eggs that are determined to be ovomucoid-containing shell eggs after the absorption amount is measured.

[0030] (Ovomucoid-free shell eggs in the calculation step) Ovomucoid-free shell eggs in the calculation step are used to derive the conversion formula. The ovomucoid-free shell eggs are as described above. Examples of ovomucoid-free shell eggs in the calculation step include shell eggs obtained from chicken breeds in which the ovomucoid gene has been deleted (knocked out) by genetic manipulation or the like. The ovomucoid-free shell eggs in the calculation step may be shell eggs that are known to be ovomucoid-free when the amount of light absorption at the specific wavelength is measured, or may be shell eggs that are found to be ovomucoid-free after the absorption measurement.

[0031] (Method of Calculating the Discriminant Value) The discriminant value is calculated by substituting the absorption amount measured in the measurement step into the above conversion formula.

[0032] (Sorting Step) The method for sorting shell eggs that do not contain ovomucoid includes a sorting step of sorting shell eggs that do not contain ovomucoid based on the discriminant value.

[0033] (Selection Method) Selection of shell eggs that do not contain ovomucoid is performed based on the calculated discrimination value of shell eggs. For example, this may be performed by comparing the calculated discrimination value of shell eggs with a preset threshold. The threshold may be preset depending on the purpose. For example, from the perspective of the accuracy of determining whether shell eggs do not contain ovomucoid, the threshold may be set low to reduce false positives, or from an economical perspective, the threshold may be set high to reduce false negatives. In other words, the threshold may be set appropriately, taking into consideration the degree to which the false negative rate and false positive rate should be balanced.

[0034] When the conversion equation is derived by PLS-DA from the results of measuring the absorption amount, with the discrimination value for shell eggs containing ovomucoid set to 1 and the discrimination value for shell eggs not containing ovomucoid set to 0, shell eggs whose absorption amount is measured may be sorted as not containing ovomucoid when the discrimination value is less than a threshold value. The threshold value may be, for example, within a range of more than 0 and not more than 0.6, or within a range of 0.05 to 0.6, 0.1 to 0.6, 0.1 to 0.5, 0.1 to 0.4, or 0.1 to 0.3, or within a range of 0.2 to 0.6, 0.3 to 0.5, or 0.4 to 0.5. Furthermore, since the proportion of shell eggs that do not contain ovomucoid among the selected shell eggs increases as the threshold is set lower, when it is desired to reduce false positives, the threshold may be set within the ranges of, for example, 0.1 to 0.4, 0.1 to 0.35, 0.1 to 0.3, 0.1 to 0.25, or 0.1 to 0.2. Since the proportion of shell eggs that do not contain ovomucoid that are selected increases as the threshold is set higher, when it is desired to reduce false negatives, the threshold may be set within the ranges of, for example, 0.35 to 0.6, 0.4 to 0.6, 0.45 to 0.6, or 0.5 to 0.6. If it is desired to reduce false positives while also reducing false negatives, the threshold value may be set within the range of, for example, 0.2 to 0.5, 0.2 to 0.4, 0.2 to 0.35, 0.3 to 0.5, 0.35 to 0.5, 0.4 to 0.5, or 0.3 to 0.4.

[0035] In the method for sorting ovomucoid-free shell eggs according to this embodiment, the measurement step through the sorting step need only be performed once, and some or all of the measurement step through the sorting step may then be performed multiple times. In this case, the conditions for the first measurement step through the sorting step may be changed. For example, the wavelength of the light of a specific wavelength in the measurement step may be changed to measure the absorbance, or the threshold value in the sorting step may be changed.

[0036] (Method for producing ovomucoid-free shell eggs) The present invention is characterized by providing a method for producing ovomucoid-free shell eggs, which includes a step of carrying out the above-mentioned method for selecting ovomucoid-free shell eggs to select ovomucoid-free shell eggs.

[0037] The method for selecting shell eggs that do not contain ovomucoid is as described above.

[0038] The present invention will be described in more detail below with reference to examples, etc. However, the present invention is not limited to the following examples.

[0039] Test Example 1: Determination of ovomucoid-free shell eggs (1) (1. Derivation of conversion formula) A total of 453 ovomucoid-containing and ovomucoid-free shell eggs (both unbroken eggs) for use in deriving the conversion formula, as shown in Table 1 below, were irradiated with light having a wavelength of 310 nm or more and 1100 nm or less, and the absorbance (absorption spectrum) of light at specific wavelengths was measured. The absorbance measurement data was then used to derive a conversion formula.

[0040] The absorbance (absorption spectrum) of light at a specific wavelength was measured by irradiating a shell egg for use in deriving the conversion formula with light having a wavelength of 310 nm or more and 1100 nm or less in a direction intersecting the long axis connecting the blunt end and sharp end of the egg so that the long axis was approximately perpendicular to the horizontal plane, and detecting the transmitted light. The absorbance measurement data was obtained using a visible-near-infrared spectrophotometer. The absorbance (absorption spectrum) measurement equipment and conditions were as follows: Equipment: Handy Lambda II NIR enh (SpectraCorp Inc.) Analysis software: The Unscrambler X (CAMO Software)

[0041] The conversion formula was derived using the following procedure. The discrimination value for shell eggs containing ovomucoid for use in deriving the conversion formula was set to 1, and the discrimination value for shell eggs not containing ovomucoid for use in deriving the conversion formula was set to 0, and the discrimination value was used as the response variable. Savitzky-Golay fitting was performed on the measured absorption spectrum with 25 smoothing points on both sides, and second-order differentiation was performed using The Unscrambler X (manufactured by CAMO Software). PLS-DA was performed on the above-mentioned response variable using the second-order derivative value of the absorbance of light of a specific wavelength in the absorption spectrum after second-order differentiation as the explanatory variable. R of the derived conversion formula ２ The coefficient of determination was a high value of 0.579, and the goodness of fit of the transformation formula was high.

[0042] (2. Determination of ovomucoid-free shell eggs) A total of 125 ovomucoid-containing and ovomucoid-free shell eggs for evaluation (both unbroken eggs) shown in Table 1 below were similarly irradiated with light having a wavelength of 310 nm or more and 1,100 nm or less. Next, the absorbance (absorption spectrum) of light at a specific wavelength was measured, and a discriminant value was calculated using the conversion formula derived in 1 above. The discriminant value was then compared with a threshold value to determine whether the shell eggs were ovomucoid-free.

[0043] The absorption spectrum was measured in the same manner as in 1 above. Then, the discriminant value was calculated by substituting the absorbance of light at the same wavelength as that used to derive the conversion formula in the measured absorption spectrum of the shell eggs into the conversion formula. For sorting of shell eggs that do not contain ovomucoid, thresholds were set to 0.5, 0.4, 0.3, 0.2, and 0.1, and eggs that were less than the respective thresholds were determined to be shell eggs that do not contain ovomucoid. The results of evaluating the discrimination rate 1 calculated using the following formula (1) are shown in Table 2, and the results of evaluating the discrimination rate 2 calculated using the following formula (2) are shown in Table 3. Formula (1) Discrimination rate 1 (%) = (number of correct answers for shell eggs not containing ovomucoid / number of shell eggs with discrimination values ​​less than the threshold) x 100 Formula (2) Discrimination rate 2 (%) = {(number of correct answers for shell eggs not containing ovomucoid + number of correct answers for shell eggs containing ovomucoid) / total number of shell eggs evaluated} x 100

[0044]

[0045]

[0046]

[0047] As shown in Table 2, when the threshold was set to 0.5, the determination rate 1 was 96.30%. Furthermore, the determination rate 1 tended to increase as the threshold was set to a lower value. This is thought to be due to a decrease in the number of shell eggs containing ovomucoid that were determined to be shell eggs not containing ovomucoid (false positives). These results demonstrate that the method performed in Test Example 1 above can be used to select shell eggs that do not contain ovomucoid with high accuracy.

[0048] Furthermore, as shown in Table 3, the determination rate 2 calculated using a calculation method such as equation (2) tended to decrease as the threshold was set to a lower value. This is thought to be because, as the threshold was lowered, the number of false positives decreased, while the number of shell eggs not containing ovomucoid that were determined to be shell eggs containing ovomucoid (false negatives) increased. Conversely, the determination rate 2 tended to increase as the threshold was set to a higher value. This is thought to be because the number of shell eggs not containing ovomucoid that were false negatives decreased. Therefore, the results in Tables 2 and 3 demonstrated that shell eggs not containing ovomucoid can be selected with high accuracy by setting an appropriate threshold depending on the purpose.

[0049] Test Example 2: Determination of ovomucoid-free shell eggs (2) (1. Derivation of conversion formula) The derivation of the conversion formula was performed in the same manner as Test Example 1, except that the wavelength of the light irradiated onto the shell eggs was changed, and the wavelength of the specific wavelength of light was changed accordingly. A total of 119 ovomucoid-containing and ovomucoid-free shell eggs (both unbroken eggs) used to derive the conversion formula, as shown in Table 4 below, were irradiated with light having a wavelength of 800 nm or more and 2500 nm or less, and the absorbance (absorption spectrum) of light at the specific wavelength was measured. The absorbance measurement data was then used to derive the conversion formula. The R of the derived conversion formula was ２The coefficient of determination was 0.701, which was a fairly high value, and the goodness of fit of the transformation formula was quite high.

[0050] (2. Determination of Ovomucoid-Free Shell Eggs) Determination of ovomucoid-free shell eggs was performed in the same manner as in Test Example 1, except that the wavelength of the light irradiated onto the shell eggs was changed, and the wavelength of the specific wavelength of light was also changed accordingly. A total of 29 ovomucoid-containing and ovomucoid-free shell eggs for evaluation (both unbroken eggs) shown in Table 4 below were similarly irradiated with light having a wavelength of 800 nm or more and 2500 nm or less. Next, the absorbance (absorption spectrum) of the specific wavelength of light was measured, and a discrimination value was calculated using the conversion formula derived in 1. of Test Example 2 above. The discrimination value was then compared with a threshold value to determine whether the shell eggs were ovomucoid-free. The results of evaluating the discrimination rate 1 calculated using the above formula (1) are shown in Table 5, and the results of evaluating the discrimination rate 2 calculated using the following formula (2) are shown in Table 6.

[0051]

[0052]

[0053]

[0054] Even when the wavelength of the specific wavelength of light was changed, the same results as in Test Example 1 were obtained. As the threshold value was set to a lower value, the determination rate 1 tended to be higher and the determination rate 2 tended to be lower. The conversion formula derived in Test Example 2 was found to have a higher R than the conversion formula derived in Test Example 1. ２ Because the coefficient of determination is high, it is thought that the accuracy of the determination will be further improved by increasing the number of lots. The above results demonstrate that the method used in Test Example 2 above can also be used to select shell eggs that do not contain ovomucoid with high accuracy.

Claims

1. A method for sorting shell eggs that do not contain ovomucoid, comprising: a measurement step of irradiating shell eggs with light containing a specific wavelength and measuring the amount of light absorbed at the specific wavelength; a calculation step of calculating a discrimination value by substituting the absorption amount into a conversion formula; and a sorting step of sorting shell eggs that do not contain ovomucoid based on the discrimination value, wherein the conversion formula is an equation derived from the results of measuring the amount of light absorbed at the specific wavelength for shell eggs containing ovomucoid and shell eggs that do not contain ovomucoid.

2. The sorting method according to claim 1, wherein the light of the specific wavelength is light having a wavelength within the range of 310 nm or more and 2500 nm or less.

3. The selection method according to claim 1 or 2, wherein the transformation formula is an equation derived by partial least squares discriminant analysis.

4. The method of claim 1 or 2, wherein the transformation formula is an equation derived by partial least squares discriminant analysis, with a discrimination value of 1 for shell eggs containing ovomucoid and a discrimination value of 0 for shell eggs not containing ovomucoid, and the selection step comprises selecting shell eggs as not containing ovomucoid when the discrimination value calculated in the calculation step is less than a threshold value, and the threshold value is within the range of more than 0 and not more than 0.

6.

5. A method for producing ovomucoid-free shell eggs, comprising a step of carrying out the selection method according to claim 1 or 2 to select ovomucoid-free shell eggs.

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