CN112505015A

CN112505015A - Method for rapidly predicting pH value of beef by Raman spectrum

Info

Publication number: CN112505015A
Application number: CN201910873066.4A
Authority: CN
Inventors: 毛衍伟; 张一敏; 朱立贤; 梁荣蓉; 董鹏程; 罗欣; 王新怡
Original assignee: Shandong Agricultural University
Current assignee: Shandong Agricultural University
Priority date: 2019-09-16
Filing date: 2019-09-16
Publication date: 2021-03-16

Abstract

The invention discloses a method for quickly prejudging the pH value of beef by Raman spectrum. The method mainly comprises the following steps: using a 785nm excitation light source, wherein the laser intensity is 100 mW; and when the half carcass of the slaughtered beef cattle is cooled for 24h, scanning a Raman spectrum for 6 times in a vertical direction by using laser and muscle fiber, deducting dark current, calculating an average spectrum, and quickly judging the pH value of the beef through an established prediction model. The method can quickly and accurately predict the pH value of the beef, remove heterogeneous meat of the black cut meat, can be integrated with a technology for quickly predicting the tenderness of the beef by Raman spectroscopy, ensures the quality of the beef and promotes the development of the beef industry.

Description

Method for rapidly predicting pH value of beef by Raman spectrum

Technical Field

The invention belongs to the technical field of beef quality control, and particularly relates to a method for quickly prejudging a beef pH value by using a Raman spectrum.

Background

With the development of economy and the improvement of the living standard of people, the consumption of beef in China is rising day by day. The quality of beef is a key factor influencing the consumption of beef, and the incidence rate of DFD (Dark, Firm, Dry) heterogeneous meat up to 17 percent restricts the development of beef industry in China. DFD Meat is also known as Dark cut Meat (Dark Cutting Meat), and the most common method for determining DFD Meat is to measure the pH of beef, but there is no uniform threshold standard for defining DFD Meat so far. At present, the lowest threshold value of 5.7 (Australia) and the highest threshold value of 6.2 (Sweden) are defined, and indexes such as meat color, intramuscular glycogen content and the like of meat researchers delphin and the like in China are analyzed, and the pH value of beef is more than 6.09 and is used as a standard for judging DFD beef.

DFD beef has two major disadvantages: first, color issues. The color of the meat is a common index for consumers to judge the freshness of the beef, and is a key factor influencing the purchasing decision of the consumers. The color of the DFD beef is dark, so that people can misjudge the freshness of people, the purchase desire of consumers is reduced, and the sale of the DFD beef is influenced by the meat color problem. In addition, during the cooking process of the DFD beef, the high pH can delay the denaturation of myoglobin, so that the cooked DFD beef continuously keeps pink, the misjudgment of a consumer on the cooking maturity is caused, and the eating quality is influenced. Secondly, the DFD beef has high pH value and short shelf life, and is easy to be infected by microorganisms to cause bad smell and sticky and smooth surface. High pH beef surface pseudomonas rapidly multiplies, thereby producing hydrogen sulfide gas, resulting in muscle surface greening. Therefore, the DFD beef has the defects of poor meat color difference, short shelf life and the like, and brings huge economic loss to enterprises.

The Raman spectrum technology is a spectrum analysis technology developed based on a Raman scattering effect, and can be used for rapid, in-situ and nondestructive detection. Different chemical bonds or groups contained in the substance, and different movement patterns of atoms or groups are the reasons for generating different raman shifts. Biochemical changes in the muscle of the slaughtered beef lead to different contents of substances such as lactic acid, phosphoric acid and the like, and the method becomes a basis for rapidly judging the pH value of the beef by applying Raman spectrum.

A relation model between the characteristic Raman spectrum and the pH value of the beef is established, a threshold value can be set, and whether products are DFD heterogeneous beef or normal beef can be judged. And classifying products according to the judgment result, carrying out industrial deep processing on the DFD heterogeneous meat, and producing cold fresh meat from normal meat, thereby providing a foundation for the classified utilization of the products and the maximized improvement of industrial benefits in the beef industry. And can be integrated with technologies such as Raman rapid determination of beef tenderness and the like, and a foundation is laid for beef classification.

Disclosure of Invention

The method for quickly predicting the pH value of the beef by the Raman spectrum is quick and effective, can be synchronously integrated with technologies for predicting the pH value of the beef by the Raman spectrum and the like, and provides technical support for beef quality control and classification and grading.

A method for quickly predicting the pH value of beef by Raman spectrum comprises the following steps:

(1) selecting equipment parameters: 785nm laser is used as an excitation light source, the laser intensity is 100mW, and the use power is 80-100%;

(2) cooling the half carcass of the slaughtered beef cattle for 24 hours at the ambient temperature of 0-4 ℃ and the air speed of 0.5 m/s;

(3) scanning laser and muscle fiber in a vertical direction to obtain a Raman spectrum, and scanning for 6 times to obtain 6 original Raman spectra;

(4) subtracting dark current from the obtained original Raman spectrum, and calculating an average spectrum;

(5) predicting the beef pH value: predicting the pH value of the beef through a prediction model according to the key Raman shift spectrum intensity of the obtained average spectrum;

the key Raman shift is 1002 and 1651cm^-1；

The pH value prediction model is that the pH value is 4.943+0.003X₁-0.002X₂；

X in pH value prediction model₁As Raman shift 1651cm^-1Strength of (2), X₂Is Raman shift 1002cm^-1The strength of (2).

The invention has the technical effects and advantages that:

according to the method, the pH value of the beef is quickly predicted by scanning the Raman spectrum of the beef and combining the intensity value of key Raman shift with a prediction model, and the beef DFD heterogeneous meat can be judged by combining the judgment standard of the beef DFD. The method is rapid and effective, and can provide technical support for beef quality classification and classification.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Examples

The technical solution of the present invention will be further described in detail with reference to the following examples.

Example 1:

(1) in a certain Shandong enterprise, 100 commercially produced beef cattle were randomly selected on a slaughter line and slaughtered according to a standard slaughter process.

(2) After slaughtering, cooling for 24 hours at 0-4 ℃, and scanning the Raman spectrum of the longissimus dorsi 12-13 ribs of the cattle by using a portable Raman spectrometer.

(3) The excitation light source of the Raman spectrometer is 785nm laser, the laser intensity is 100mW, and the use power is 80%. Scanning for 6 times to obtain 6 original Raman spectra with the laser and the muscle fiber in the vertical direction;

(4) subtracting the dark current of the Raman spectrum obtained in the step (3) by using self-contained software of an instrument, and calculating an average spectrum;

(5) at key Raman shifts 1002, 1651cm^-1Spectral intensity and prediction model pH 4.943+0.003X₁-0.002X₂(X₁As Raman shift 1651cm^-1Strength of (2), X₂Is a Raman shift of 1002cm^-1Intensity) predicted beef pH. The pH value of the meat was 6.09 as a threshold, and the incidence of DFD-containing meat was 23%.

(6) And (4) dividing and taking the west cold, measuring the pH value of the west cold by using a pH meter when the beef is ripe for 7d, and determining that the occurrence result of the DFD beef determined by the pH value measured by the pH meter is consistent with the prediction result of the Raman spectrum.

Example 2:

(1) and (3) randomly selecting 180 commercially produced beef cattle on a slaughtering line by a certain enterprise in an inner Mongolia autonomous region, and slaughtering according to a standard slaughtering process.

(2) And cooling the half carcass of the slaughtered beef cattle for 24 hours at the temperature of 0-4 ℃, and scanning the Raman spectrum of the longissimus dorsi of the cattle at the position of 5-6 ribs by using a portable Raman spectrometer.

(3) The excitation light source of the Raman spectrometer is 785nm laser, the laser intensity is 100mW, and the use power is 90%. Scanning for 6 times to obtain 6 original Raman spectra with the laser and the muscle fiber in the vertical direction;

(5) at key Raman shifts 1002, 1651cm^-1Spectral intensity and prediction model pH 4.943+0.003X₁-0.002X₂(X₁As Raman shift 1651cm^-1Strength of (2), X₂Is a Raman shift of 1002cm^-1Intensity) predicted beef pH. The pH value of the meat is 6.09 as a threshold value, and the incidence rate of the DFD heterogeneous meat is 8 percent. (6) And (4) cutting eye flesh, measuring the pH value of the beef by using a pH meter when the beef is ripe for 7d, and determining that the occurrence result of the DFD beef determined by measuring the pH value by using the pH meter is consistent with the prediction result of the Raman spectrum.

Claims

1. A method for quickly predicting the pH value of beef by Raman spectrum is characterized in that: comprises the following steps:

(1) setting parameters: a 785nm excitation light source is adopted, the light source intensity is set to be 100mW, and the use power is 80-100%;

(2) sample treatment: cooling the half carcass of the slaughtered beef cattle for 24 hours at the ambient temperature of 0-4 ℃ and the air speed of 0.5 m/s;

(3) obtaining an original raman spectrum: performing laser scanning on the sample obtained in the step (2), scanning the laser and the muscle fiber in a vertical direction, and scanning each half carcass for 6 times to obtain 6 original Raman spectrums;

(4) processing of Raman spectrum: subtracting dark current from the original Raman spectrum obtained in the step (3), and calculating an average spectrum;

(5) predicting the beef pH value: and (5) predicting the pH value of the beef through a prediction model according to the key Raman shift spectrum intensity of the average spectrum obtained in the step (4).

2. The method for rapidly prejudging the pH value of the beef by using the Raman spectrum as claimed in claim 1, which is characterized in that: the key Raman shift of the step (5) is 1002 and 1651cm^-1。

3. The method for rapidly prejudging the pH value of the beef by using the Raman spectrum as claimed in claim 1, which is characterized in that: the pH value prediction model in the step (5) is that the pH value is 4.943+0.003X₁-0.002X₂。

4. The method for rapidly prejudging the pH value of the beef by using the Raman spectrum as claimed in claim 3, which is characterized in that: x in pH value prediction model₁As Raman shift 1651cm^-1Strength of (2), X₂Is Raman shift 1002cm^-1The strength of (2).