Identification of food authenticity by the hottest

2022-09-19
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Identification of food authenticity by infrared spectroscopy

food safety is one of the important contents of the national "Eleventh Five Year Plan". For the life and health of hundreds of millions of people and the stability and harmony of the whole society, government departments and regulatory agencies should not only have sound laws and regulations, but also rely on advanced technical means to build solid food safety protection and do a good job in this major event related to the national economy and the people's livelihood, In addition to the food standard system, the development of advanced technology with wide applicability, convenient operation, fast speed and accurate results is also a top priority for the supervision and testing of food safety. The application of modern infrared spectroscopy in the supervision and detection of food safety will certainly promote the construction of China's food quality and safety assurance system

In recent years, the research group of Professor Sun Suqin from the Department of chemistry of Tsinghua University has been studying the application of modern infrared spectroscopy technology in the authenticity identification of traditional Chinese medicine, health products and food and the quality control of traditional Chinese medicine. The raw materials of food, health care products and traditional Chinese medicine are all from plants, animals or minerals, so there are certain commonalities between them. They have made outstanding achievements in this field, successfully taking infrared spectroscopy as the core technology of connotation anti-counterfeiting and quality detection

infrared spectrometer is a general instrument in instrumental analysis, and infrared spectroscopy is one of the most mature means in organic structure analysis. Infrared spectroscopy is based on the characteristic vibration of the groups contained in the molecules. Ningbo has launched the plan to build an international new materials science and technology city to judge and identify compounds. At present, it is a widely used analytical method in western medicine identification in Pharmacopoeia of various countries. However, because food and traditional Chinese medicine are not single component compounds, but a mixture system composed of a variety of chemical substances, coupled with the large amount of information contained in the infrared spectrum, it is difficult to identify and other reasons, this analysis method has not been applied in complex systems. The research shows that as long as the chemical components in the complex system are the same and the relative proportion of each component is certain, the infrared spectrum obtained is the spectral superposition of all compounds in the system. It will be the same as the spectrum of a single compound and can be repeated stably. If there is any change in the composition or content of the sample, there will be obvious differences in the spectrum, which provides an objective and reliable basis for the identification of the authenticity of the sample and the evaluation of its advantages and disadvantages. Therefore, the basic principles of authenticity identification and quality control of traditional Chinese medicine and food are exactly the same

food connotation anti-counterfeiting

health products are a special kind of food. Many health care products on the market have exquisite packaging and boast of unique effects, deceiving people who are eager for health. Driven by interests, unscrupulous businessmen often make fake goods that are not worthy of the name. Many fake health products are actually just ordinary food

Professor Sun's research group has carried out infrared spectrum analysis and Research on many varieties of health products. From the infrared spectrum, it is easy for us to see the authenticity of health products and expose the despicable tricks of food manufacturers

after a lot of experimental work, we tested Ganoderma lucidum health products of different brands and found that compared with standard Ganoderma lucidum samples, the content of real effective ingredients in this kind of health products on the market is very small, or not at all, mainly added excipients, such as starch, sucrose, lactose and other substances

Figure 1 is ×× Infrared spectrogram of pure Ganoderma lucidum powder, real Ganoderma lucidum and lactose. Figure 2 is ×× Infrared spectrogram of brand Ganoderma lucidum capsule products, real Ganoderma lucidum and its excipients. Comparing the spectrum of the two products with the peak position, peak shape and peak intensity of true Ganoderma lucidum, lactose and starch, it can be seen that the product declared as pure Ganoderma lucidum powder basically contains no Ganoderma lucidum components, but only contains a large amount of lactose. The Ganoderma lucidum capsule, which is claimed to be "authentic wild", does not contain Ganoderma lucidum, and the substance in the capsule is basically starch

using the same method, we tested the ginseng tea products on the market. The results showed that the common characteristics of different brands of ginseng tea were very prominent, that is, they did not contain or rarely contained the ingredients of American ginseng, and the differences were also very obvious. That was because the substitutes used were different, some were sucrose, some were glucose, etc

health products that claim to take "bird's nest" as the main ingredient have also been studied. Firstly, the characteristic absorption peaks of infrared spectra of protein, amino acids and polysaccharides in natural bird's nest were determined. The absorption peak of fake bird's nest cannot have the characteristics of genuine bird's nest. What exactly is used to forge bird's nest? After a detailed analysis of various brands of bird's nest health products, the research group finally determined that the fake products in bird's nest health products were mostly processed with gelatin, tremella and fried pig skin. People who buy and use health products can't imagine that ordinary foods such as fried pork skin have changed into bird's nests

infrared spectrogram gives us a pair of insight. Even those who do not understand infrared analysis at all can judge whether it is genuine or fake by a slight comparison of the information provided by the spectrogram. Experienced technicians can further see through the manufacturers' deceptive tricks according to the spectrum to determine what low-quality and cheap things they use to pretend to be genuine products. The application of infrared spectroscopy in the supervision and detection of food safety is an excellent connotative anti-counterfeiting technology. It relies on the most essential and comprehensive infrared spectroscopy information provided by the chemical composition of all substances and molecules in food to make a correct judgment of authenticity

food quality detection

Professor Sun's research group has studied many kinds of food by infrared spectroscopy, such as Baijiu, wine, edible oil, milk powder, chocolate, honey, coffee, butter, meat products, etc. The results show that these types of food can realize the connotation of food anti-counterfeiting and food quality detection by the information on the infrared spectrum, It can be used as the evaluation of food quality and the purpose of macro quality control in the production process

for example, the brand milk powder on the market has been tested, and the infrared spectra of more than 50 milk powder products have been obtained by Fourier transform infrared spectroscopy (FTIR). The main nutrients in milk powder have obvious fingerprint characteristics in infrared spectrum. In the spectrum with high fat content in milk powder, the C = O absorption peak near 1747cm-1 and the CH2 absorption peak near 2926cm-1 are very strong at the same time. The C = O absorption peak (1650cm-1) of amide I band and the N-H and C-N absorption peaks (1540cm-1) of amide II band corresponding to high protein are stronger; The C-O stretching vibration peak and ring vibration peak corresponding to gb/t16491 (2) 008 electronic universal testing machine for carbohydrates in milk powder are significantly in the range of 1150 ~ 900cm-1. Maltodextrin, sucrose and lactose, three commonly used excipients, also have obvious fingerprint characteristics, which change with the addition amount. However, protein, fat, sugar, moisture and other components in milk powder are the core indicators to measure the quality of milk powder, and they are also the key links that affect the quality of milk powder

from the infrared spectra of three middle-aged and elderly milk powders in Figure 3, it can be seen that the absorption peak of c=o double bond near 1747cm-1 of milk powder a fat is higher than that of protein amide I band (1650cm-1), indicating that the oil content is higher, while the peak of c=o double bond near 1747cm-1 of milk powder B and C is significantly lower than that of protein amide I band (1650cm-1), And the c=o absorption peak (1650cm-1) of protein amide I band is very strong, indicating that the protein content is high. It can be seen from the figure that the oil content of milk powder a, B and C decreases step by step, and the protein content increases step by step

with the help of the second derivative spectrum, see Figure 4. In the range of 1400 ~ 800cm-1, it can be seen that the C-O stretching vibration peak and the ring vibration peak in the range of 1150 ~ 900cm-1 in the three brands of milk powder are very similar, indicating that the type of sugar added is the same, but from the figure, we can see that the relative strength of the peak made of metal on the A-pillar on both sides of the two mini large windscreens of 893cm-1 and 874cm-1 is significantly different in the three kinds of milk powder, This is caused by the different content of added sugar. This peak can be used as the characteristic peak to identify the sugar content. The sugar content in milk powder a, B and C increases in turn. Through the above comparison, it can be concluded that the quality of the above three kinds of middle-aged and elderly milk powder, brand C is the best, brand B is the second, and brand a is poor

if the content of fat and protein in milk powder is lower than the value of food standards, then it is not a problem of poor quality, and it has become a fraud of "Anhui Fuyang". In this way, the application of infrared spectroscopy technology in the supervision and detection of food safety can not only accurately judge the authenticity, but also judge the advantages and disadvantages according to the content of active ingredients

at present, the quality of many foods in the market is not guaranteed. Olive oil is mixed with a certain amount of low-cost edible oil of other varieties, honey is mixed with starch and sucrose, cooked meat products are mixed with low-cost meat skin or other varieties of meat, etc., all of which are exposed in infrared spectrum analysis

infrared spectroscopy has the characteristics of synthesis, integrity, authenticity, objectivity and Science in identifying the authenticity of food and judging the advantages and disadvantages of food. First of all, in the analysis and identification of this method, there is no need to pretreat the sample, and direct sampling and determination, so as not to lose the authenticity of the sample; It also does not destroy various components. Secondly, the peak position, peak shape and peak intensity in the measured spectrogram represent the spectral peaks of the corresponding groups contained in the system. It reflects the superposition spectrogram of various components in a mixture and is the essential feature of the test sample itself. Changes in the composition, content and other factors in the mixture will cause changes in the overall spectrum. With these macro characteristics, food identification and quality control can be achieved

in practical application, the infrared spectrogram of famous and high-quality brand products is taken as the standard spectrogram for authenticity identification and product quality control, and other samples are quickly analyzed. After the analysis and comparison of spectrograms, it can be directly judged and made a qualitative evaluation, or the spectrogram can be slightly mathematically processed and then made a quantitative judgment. In addition, infrared spectrometer is a general analytical instrument, which is easy to operate and easy to be popularized and applied

in addition, food safety is not limited to the quality of food internal substances, the safety of food raw materials, the safety of food production equipment and processes, the safety of food external packaging, the safety of food transportation and storage, etc., but also should be given sufficient attention. Infrared spectroscopy can also play an important role in the demonstration of these aspects

in order to ensure food safety, infrared spectroscopy detection of food should be combined with other technologies to ensure the quality and hygiene of food (including the residues of bacteria, heavy metals, harmful pesticides, etc.); At the same time, various anti-counterfeiting technologies such as anti-counterfeiting marks on food packaging should be used in conjunction with connotative anti-counterfeiting, so that the masses and regulatory agencies can jointly participate in the people's war against counterfeiting and fidelity

in a word, the quantity safety and quality safety of food are the two basic contents of food safety. Since the reform and opening up, the Chinese government has made remarkable achievements in solving the quantity safety of food, but there is still a long way to go to solve the problem of food safety. It is believed that infrared spectroscopy will play a role in promoting the construction of China's food quality and safety assurance system

text/Wang Junmin

source: Chinese brands and anti-counterfeiting

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