In recent years, in food supervision and inspection, reports of aluminum content in pasta products exceeding national standards have occurred and are more serious. We know that aluminum is a toxicologically low-toxic metal element and generally does not cause acute poisoning. However, excessive intake of aluminum can destroy the function of genetic material in nerve cells, leading to brain damage and impairing memory function. In order to curb the recurrence of aluminum content exceeding the standard in food, we have made new breakthroughs in the technology of quick-freezing point aluminum detection.

Aluminum is a common metal element in nature and is closely related to people in daily life. In foods, especially in pasta, the wide use of aluminum-containing additives (such as alum, baking powder, etc.) allows aluminum to enter the body through the food chain. Aluminum is a toxicologically low-toxic metal element and generally does not cause acute poisoning. However, excessive intake of aluminum can destroy the function of genetic material in nerve cells, leading to brain damage and impairing memory function. Moreover, excessive aluminum may also affect the body's absorption of calcium (Ca), iron (Fe), and phosphorus (P), leading to anemia and insufficient calcium in the human body, causing osteoporosis and prone to fracture.

Improper detection of aluminum, damage to frozen noodle manufacturers

Long-term intake of excessive aluminum in the human body has an adverse effect on health. Therefore, in 1989, the World Health Organization officially determined that aluminum was controlled as a food contaminant, and the daily allowable intake was 1 mg/kg body weight; the National Health and Family Planning Commission and other five departments announced the regulation on the use of aluminum-containing food additives ( No. 8 of 2014), since July 1, 2014, the use of acidic sodium aluminum phosphate, sodium aluminosilicate and octenyl succinate aluminum starch for the production, management and use of food additives is prohibited. Use of aluminum-containing food additives; GB2760-2014 requires that, in addition to fried noodles and batter (such as batter paste for fish and poultry), breading, frying powder, potassium aluminum sulfate should not be used in the production of wheat flour and its products. And ammonium aluminum sulfate, which can also be used to control the aluminum content is ≤ 100mg / kg.

Among them, according to the national standard GB25591-2010, the food additive composite leavening agent should indicate the aluminum content of the product on the packaging label, including the composite leavening agent without the additive containing aluminum.

According to Guangzhou Food Industry Research Institute Co., Ltd. and some of its customers (manufacturers), its production of package points, dumplings, compound leavening agents, etc. were detected by the law enforcement agencies in the market supervision and contain aluminum content of up to 200mg/kg. However, in the actual production, aluminum-containing raw materials have never been added, which has caused the manufacturer to suffer damage.

At present, there are two methods for detecting aluminum, GB/T5009.182-2003 "Determination of aluminum in pasta" spectrophotometry and GB/T23374-2009 "Inductively coupled plasma mass spectrometry for determination of aluminum in food". Because the instruments used in inductively coupled plasma mass spectrometry are expensive and costly, most of the testing institutions and food companies still use spectrophotometry, and the spectrophotometry is not very effective in practical operation.

In order to avoid the manufacturer's limited exposure and unacceptable test results, the aluminum content of the products produced exceeds the standard and enters the market, resulting in legal sanctions and unnecessary economic losses.

This study is mainly to improve the existing detection methods (GB/T5009.182-2003 and Appendix B of GB25591-2010), using spectrophotometry to reduce the interference of other factors on the determination of aluminum, so that the aluminum content is closer to the true value. .

Compared with the existing national standard detection method, the improved spectrophotometry uses cation exchange resin to remove the interference of anions such as phosphate and perchlorate, and masks iron with ascorbic acid; in the acetic acid-sodium acetate buffer solution, aluminum and chromium days Cyan S and cetyltrimethylamine bromide form a chromium compound, which can effectively remove the interference of anion on the determination, and the operation is simple and fast, and the accuracy and precision are good, and the effect is remarkable; and the spectroscopic light is enhanced by adding an sensitizer. Photometric method for measuring the sensitivity of aluminum.

The improved spectrophotometry provides an economical and applicable testing method, which is of great significance for regulating the production and operation activities of the food industry, enhancing the standardization, scientificity and effectiveness of food safety supervision in this field, and ensuring food safety.

Improved chrome azurol S spectrophotometry

●Pretreatment method of sample

After the sample has been subjected to digestion treatment, it is pretreated by a cation exchange resin before measurement.

The operation method is as follows: the exchange column is packed with 5 mL of cation exchange resin, the pH value of the sample is adjusted to 7.0, and the sample liquid is rinsed with 50 mL of ultrapure water at a rate of 2 to 2.5 mL/min, and then the concentration of 20 mL is 4 mol/L. The hydrochloric acid was eluted at a rate of 2 to 2.5 mL/min.

●Optimization test of detection method

Pipette aluminum standard solution 0.00mL, 0.50mL, 1.00mL, 2.00mL, 3.00mL, 4.00mL, 5.00mL in a 25mL volumetric flask, add 1% sulfuric acid 1.00mL in turn, then shake up, add 10g / L Ascorbic acid solution 1.00mL, 0.5g / L chrome azurol S solution 2.00mL, shake well, add 10g / L cetyltrimethylammonium bromide 1.00mL, gently shake, add 7.00mLl95% ethanol, gently shake After homogenization, 5.00 mL of acetic acid-sodium acetate buffer solution (pH = 6.00) was added and diluted to the mark with water. After standing at room temperature for 30 min, a 1 cm cuvette was used on a spectrophotometer, and the blank was adjusted to zero at 619 nm. The Abs value was plotted on the ordinate and the aluminum content was plotted on the abscissa.

●Sample measurement

Comparison of test results of different raw materials and different methods.

a. Titration method - "Food safety national standard food additive composite leavening agent" GB25591-2010 Appendix D aluminum determination method;

b. Patent Law - Improved chrome azurol spectrophotometry;

c. Mass spectrometry - "Induction of aluminum in foods by inductively coupled plasma mass spectrometry" GB/T23374-2009.

The improved aluminum “content” detection method reduces the interference of other factors in the sample to be tested, which is basically consistent with the results measured by mass spectrometry, so that the aluminum “content” value is closer to the true value, and the probability of the aluminum “content” in the food exceeds the standard. Lowering down, so that manufacturers avoid legal sanctions, reduce unnecessary economic losses, reduce the people's panic about food safety, increase the confidence of food production practitioners, and provide reference for food processing and safety testing, even Can provide reference for the revision of existing national standard methods