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Turtle paste is a traditional medicinal meal with a long history in southern China, especially in the Liangguang region, and can be brewed with turtle paste powder. Turtle paste powder is made of cool powder (starch, cool powder grass extract), earth porridge, turtle, dandelion and honeysuckle as the main raw materials, and can be combined with monk fruit, chrysanthemum, laurel and other Chinese medicinal materials to make a series of products with different tastes and functions, which are deeply loved by the public.
However, with the acceleration of industrialization, the problem of environmental pollution has become increasingly prominent, and heavy metal pollution of crops has become a major aspect of food pollution. As a plant-derived food, turtle paste powder products are easily affected by environmental pollution. Today, when food safety is getting more and more attention, it is of great practical significance to analyze and study the status quo of heavy metal pollution in sensitive foods in order to control the entry of heavy metals into the food chain and ensure the health of the majority of residents. In this experiment, the product of turtle paste powder was used as the research object, and the pollution status was evaluated by measuring the heavy metal content, in order to provide a scientific basis for the quality and safety management of food.
Materials and methods
The research on the turtle paste powder products produced by three representative turtle cream manufacturers in South China was investigated. A total of 101 samples of different batches of turtle paste powder products and their main production raw materials were selected by random sampling for testing. Turtle paste powder products, cool powder and animal and plant raw materials are all powdered, particles less than 0.074mm, no need to grind; Cool powder grass (hay) for production is first rinsed with tap water, then cleaned 3 times with deionized water, and ground through an 80-mesh sieve. All samples were dried at 60 °C to constant weight and set aside. Weigh 0.5g of sample (accurate to 0.0001g) in a PTFE digestion cup, add 4ml HNO3, 2ml H2O2 for microwave digestion, and digest until transparent and clear. Cool, set to 25ml, ready for testing. The reagents used in the treatment process are all high-grade pure, and the water used is first-class pure water.
The lead content detection method adopts the graphite furnace atomic absorption spectroscopy method in the "Determination of Lead in Food Safety National Standard for Food Safety" (GB5009.12-2010), and the detection instrument is Hitachi graphite furnace and flame atomic absorption instrument Z-5000.
The arsenic content detection method adopts the hydride atomic fluorescence photometry in "Determination of Total Arsenic and Inorganic Arsenic in Food" (GB/T5009.11-2003), and the detection instrument is SK-prefective atomic fluorescence spectrometer.
Data processing is carried out using SPSS12 software. The measured values were averaged over 2 replicates. The single-factor pollution index method and the comprehensive pollution index method were used for evaluation. Single-factor pollution index method: Pi=Ci/Si formula: Pi is the single-factor pollution index of the pollutant i in the sample; Ci is the measured data of contaminant i in the sample; Si is the evaluation standard for pollutant I. Formula: P is the comprehensive pollution index of the test sample; P flat is the average value of the single-factor contamination index of the sample. Pmax is the maximum value of the single-factor contamination index of the sample.
Heavy metal content of turtle paste powder products
The results of the determination of heavy metal lead and arsenic content of the samples of turtle paste powder are analyzed in Table 2. The results showed that the detection rate of heavy metal elements lead and arsenic in the sample batch was 100%, but the content of the two elements in the sample was quite different.
Among the 56 samples tested, the lead content ranged from 0.76~2.58mg/kg, and the detection amount varied greatly. According to the national standard "Limit of Contaminants in Food" (GB2762-2012), the lead content is not more than 1.0mg/kg, and the lead exceeding rate of the tested sample is 66.1%. The lead excess rate of samples from the three different production plants varied widely, with the highest exceeding rate reaching 94.1% and the lowest being 25.0%. Different manufacturers and different batches of products are contaminated with lead, indicating that the products are greatly affected by the unstable factors of raw and auxiliary materials. The arsenic content in the tested samples ranged from 0.10~0.26mg/kg, which was lower than the sanitary limit standard of 0.5mg/kg, and no excessive batches were found.
Evaluation of heavy metal content in turtle paste powder
The single-factor contamination index, comprehensive contamination index and contamination status of the tested samples are calculated as averages in Table 3. The results showed that the lead single-factor pollution index range of the three manufacturers sampled was 1~2, indicating that these products were slightly contaminated with lead. The sample PAs were less than 1, the contamination level was clean, and the product was not contaminated with arsenic. From the perspective of comprehensive pollution index (P comprehensive), the samples were mainly at the light pollution and alert level, which was basically consistent with the evaluation conclusion obtained by using lead single-factor pollution index. It can be seen that the tested turtle paste powder products are mainly contaminated by heavy metal lead, and long-term consumption of these products has certain risks to human health.
Heavy metal source analysis
In order to analyze the source of heavy metal lead in turtle paste powder products, this experiment started from the production of raw and auxiliary materials, and 3 raw materials were taken from each of the three manufacturers for lead content test, and the average value was used as the measurement result, see Table 4. The results showed that the lead content of production water and starch was not detected (lead detection limit: production water 2.5ng/L; Starch 0.05mg/kg), the detection rate of lead in the rest of the production raw materials is 100%. The starch lead content is far lower than the sanitary limit index of 1.0mg/kg, which meets the requirements of production and use.
According to the national standard "Drinking Water Sanitation Standard" (GB5749-2006), the lead content is not more than 0.01mg/L evaluation, and the production water meets the hygiene requirements. Other animal and plant raw materials mainly refer to animal and plant raw materials other than cool powder grass, such as: poria, turtle (whole turtle or turtle plate), dandelion, honeysuckle and monk fruit, etc., usually extracted and prepared into powder in a certain proportion and used.
Since these raw and auxiliary materials belong to the category of Chinese herbal medicines, this experiment is evaluated according to the lead content limit index of Chinese herbal medicines not more than 5.0mg/kg, and its pollution index is low, which is a clean grade and meets the requirements of production and use. As the largest raw material for production, the lead content of cool powder grass is high, with an average value of up to 5.22mg/kg. Due to the lack of hygiene standards for cool powder grass, this experiment chose to refer to the lead limit index in tea leaves not more than 5.0mg/kg for evaluation.
The single-factor pollution index of lead in cool powder grass is close to or greater than 1, and the pollution level is light pollution. Since the multi-energy extraction pot is used in industrial production to extract the vegetable gum in cool powder grass, the extraction rate is higher than that of general immersion extraction, so the leaching rate of lead element in cool powder grass is also correspondingly increased, resulting in an increase in the degree of lead contamination of the product. The average lead content of the tested cool powder samples was greater than 2mg/kg, and the lead single-factor pollution index showed that the pollution level reached medium pollution. Although the cool powder samples taken this time belong to the production of semi-finished products, they need to be mixed with a certain proportion of starch and other animal and plant raw materials. The lead concentration of the product will be reduced to a certain extent after proportioning, but because cool powder is the main raw material of turtle paste powder products, its pollution is still worthy of concern.
It can be inferred that the lead element in the detected sample of turtle paste powder mainly comes from the raw material of cool powder grass. The pollution status of cool powder grass directly affects the quality and safety of turtle paste powder products.
Through the sampling and analysis of turtle paste powder products in three production plants, it was found that the lead contamination of such products was widespread, and the lead in the products mainly came from the production raw material - cool powder grass. Lead is an accumulation of heavy metal toxins, which mainly damage the nerves, hematopoiesis, digestive system, kidneys and the body's immune system, so that the body's resistance is reduced. Therefore, the quality and safety management of turtle paste powder products cannot be ignored, especially the quality control of raw materials.
The safety of raw material quality is affected by variety, geographical environment, climatic factors, etc., and strengthening source management is the most practical and effective method. The quality and safety of Cool Powder Grass depends to a large extent on the pollution level of the planting soil and irrigation water. Production enterprises to establish a stable and safe raw material production base, control the raw material planting process, or establish a closer supply relationship with the raw material production base are the most effective ways to control the quality and safety of raw materials. The second is to do a good job in the acceptance of raw and auxiliary materials entering the factory. Starting from the identification of raw and auxiliary materials, whether they come from the recorded production base, and whether they meet various health standards after inspection, we strictly control the quality and safety of raw and auxiliary materials.
In addition, it is necessary to strengthen the management of production and processing links. Cool powder grass needs to be dried and refined to extract liquid, while cool powder grass is easy to stick to soil during harvesting and drying. If the cleaning is not clean, the entrained soil can precipitate heavy metal elements during the extraction process and integrate them into the extraction solution, affecting the quality and safety of downstream products. Therefore, we must grasp every link of production, and have corresponding quality and safety control procedures in the production process, so as to find problems in time and prevent unqualified products from leaving the factory or flowing into the next process. Since this experiment did not further analyze whether cool powder grass has strong enrichment capacity for lead, the establishment and improvement of the entire production monitoring system still needs to be explored in the future.