Harmful residues in food can coatings BADGE

1. BADGE in Food Can Coatings

The inner coating of the food tank is an organic coating applied on the inner wall of the metal tank, which can prevent the content from directly contacting with the metal, avoid electrochemical corrosion, and improve the shelf life of the canned food. However, the chemical contaminants in the coating also migrate to the canned food during the processing and storage of cans and contaminate the contents. Such chemical contaminants mainly include BADGE (bisphenol-A diglycidyl ether), NOGE (novolac glycerol ether) and derivatives thereof. They are widely used in the production of can coatings as epoxy phenolic inner coatings, PVC inner coatings, polyester inner coating raw materials, thermal stabilizers and reinforcing agents, during high pressure sterilization and room temperature storage of canned foods. , BADGE, NOGE will migrate to the contents to induce food safety hazards.

Environmental toxicology defines such substances as environmental hormones, also known as "extrinsic endocrine disruptors," which play a role in the disproportionate sex of animals in the ecosystem. People have a sober understanding and effective analysis methods for the teratogenic carcinogenicity of chlorinated hydrocarbons, and the ecological hazards of such environmental hormones have not been discovered and recognized until recently, and have become a hot topic for environmental toxicology research. EU Directive 2002/16/EC strictly limits the use of these substances, ie the total amount of BADGE and its four derivatives (BADGE.2HCl, BADGE.HCl, BADGE.HCl.H2O, BADGE.H2O) should be <1mg. /kg, formally implemented from December 31, 2005. Regarding the safety of NOGE, SCF recommends that the total dissolution value of all NOGE-containing components and their chlorohydrogen derivatives with a molecular weight of <1000 Da should be <1 mg/kg, and the detection limit of NOGE in food contact materials should be 0.2 mg. /6dm2, This directive has been implemented since March 1, 2003.

2. BADGE and its derivatives in canned foods

BADGE is a condensation product of bisphenol-A and epichlorohydrin. It has a strong fat-soluble property and exists in the form of various derivatives in fish and canned meats with high oil content. The migration mechanism is different depending on the type of canned food. The content is slightly different.

Uematsu et al. [1] investigated 16 fish cans sold on the Japanese market. There were 11 samples (oil phase) detected BADGE, up to 12.9 mg/kg, and 2 samples detected BADGE.2HCl 0.7 mg respectively. /kg and 2.1mg/kg. In 2000, Uematsu et al. [2] found out that 28 coffee cans and 18 canned corn cans and canned tomatoes produced in the United States, Australia, Thailand, Italy, China, and Japan detected 1 coffee and 4 baby corns. BADGE.2HCl, BADGE.HCl.H2O, and BADGE.2H2O were detected at levels of 0.05-0.14 mg/kg, 0.17-0.32 mg/kg, and 0.28-4.03 mg/kg, respectively; there were 4 tomatoes and 1 small corn. The contents of BFDGE.2HCl, BFDGE.HCl.H2O, and BFDGE.2H2O were 0.11 to 0.42 mg/kg, 0.24 to 1.08 mg/kg, and 0.15 to 0.70 mg/kg, respectively. Theobald et al. [3] investigated 382 fish cans produced in 15 EU countries and Switzerland, and 3% of samples had BFDGE concentrations exceeding 1 mg/kg. Brem et al. [4] investigated 101 canned asparagus, canned anchovies, and canned tomatoes in glass bottles from 19 countries. The levels of BADGE detected in broilers, baby corn, and peppers were 1.0 mg/kg, 3.6 mg/kg, and 5.6 mg, respectively. /kg. In foods containing salt, BADGE and NOGE dissolved in paints can be converted into chlorohydrin derivatives, and chlorohydrin derivatives are considered to be the leading culprits in causing somatic cancer in animals.

3. NOGE and its derivatives in canned foods

NOGE is a mixture of novolac polyvalent glyceryl ethers with variable molecular weights, and the NOGE with the lowest molecular weight is called BFDGE. Food can coatings contain 30% to 40% bicyclic (2R-) NOGE (ie BFDGE), a small amount of tricyclic (3R-) ~ 8H-NOGE, 2R-NOGE, 3R-NOGE and 4R-NOGE homologs There are 3, 7 and 27 isomers respectively. It can remove HCl (hydrogen chloride gas) released from PVC polyorganosol coatings at a high temperature of 190°C and convert the epoxy groups into chlorohydrins [5]. Uematsu et al. conducted a sample survey of various cans sold on the Japanese market. The concentration of NOGE in 26 canned varieties was 1.2-6.9 mg/kg, exceeding the limit value of the EU Directive <1 mg/kg, which indicates that the migration of NOGE can not be ignored. . Since the molecular structure of NOGE is similar to that of BADGE, it is considered that there is also a hidden danger of food safety. The deadline set by the European Union for the use of NOGE in packaging materials for direct food contact is December 31, 2004.

4, detection methods

The complex structure and trace amounts of BADGE and its derivatives in canned foods must be analyzed using sophisticated instruments. HPLC, HPLC-MS, and GC-MS are currently the most effective analytical instruments for quantitative analysis and structural characterization. Table 1 lists the analysis methods and application examples adopted abroad.

Table 1 Detection of BADGE and Its Derivatives in Food Can Coatings

sample

Tester

Extraction Method

Measurement conditions

Analytical method

Recovery rate%

The detection limit

Mg/kg

Fried fish

BFDGE

N-hexane-acetonitrile, liquid, liquid extraction

Spherisorb ODS-2 column, acetonitrile-water (60-40), gradient method.

HPLC-FD

GC-MS

82.9-102.9

0.056

Coffee vegetables

BADGE

BFDGE

DB-5 column (15m × 0.25mm) 60°C (3min) → 20°C/min → 320°C (5min)

HPLC-FD

GC-MS

0.02-0.04

(BADGE) 0.04-0.08

(BFDGE)

Cans

NOGE and its chlorohydrins

N-hexane-MTBE

(1?1) Extraction

Sphersorb ODS-2, gradient solvent for water, methanol and ethanol.

RPLC-FD

75-124

63-10

(hydrolysis

product)

0.2-1.0

canned fish

BADGE

And its derivatives

15% dichloromethane-n-heptane extraction

Gromsil100CN2PR column,

A liquid: 2% 1-propanol-pentane;

Solution B: 50% 1-propanol-MTBE.

GC column: PS-255, 80°C (1.5 min)→15°C/min→350°C (10 min)

HPLC-FD

GC-MS

91.9-

95.4

0.1

4 Conclusion

The analysis method of BADGE and its derivatives in internal coatings is a research hotspot for food safety inspections in various countries. There are a large number of articles published every year, but domestic related researches are rarely reported. At present, China's national standards concerning the hygienic indexes of epoxy cans are: GB4805-94 “Sanitary Standards for Epoxy Phenolic Coatings on Food Cans”, GB9686-88 “Sanitary Standards for Polyamide Epoxy Coatings on Food Containers”, GB11677- 89 "Sanitary Standards for Water-based Modified Epoxy Can Ends". The test items are also limited to free phenol, evaporation residue, potassium permanganate consumption and heavy metal content, and it is far from meeting the needs of canned food exports.

China is a big exporter of canned food. The accession to the WTO has provided more room for the development of the canned industry. The export volume of canned products is increasing at a rate of 20% year by year, and exported to canned foods in economically developed countries such as Japan, the United States, Italy, and Germany. It has accounted for more than 55% of China's total exports. However, the good development momentum has been frequently suppressed by technical barriers. The statutory directives of the developed countries are like an insurmountable barrier that almost weighs on the soft underbelly of China's food packaging standards. More and more importers require our canned export companies to provide internal coatings. With the proof of NOGE and BADGE, canned export companies have no choice but to take advantage of business opportunities or directly entrust foreign authorities to inspect. This embarrassing situation exposes the fact that the hygienic standards for food packaging materials in China are seriously lagging behind. Therefore, our food The supplement and improvement of packaging hygiene standards are imminent.

references

[1] Uematsu Y, Hirokado M, Hirata K, et al. Analysis of BADGE in edible-oil-containing canned fish [J] Journal of the Food Hygienic Society of Japan, 1998, 39:135~142

[2]Uematsu Y, Hirata K, Suzuki K, et al. Chlorohydrins of bisphenol A diglycidyl ether (BADGE) in canned foods [J]. Food Additives and Contaminants, 2001,18(2): 177~185

[3]Theobald A, Simoneau C, Hannaert P, et al. Occurrence of bisphenol F diglycidyl ether (BFDGE) in canned fish in oil [J]. Food Additives and Contaminants, 2000,17(10): 881~887

[4]Brem S, Biedermann M, Grob K, et al. Migration from the internal coatings of canned food: Campaign 2000 on the Swiss market [J]. Mitteilungen aus Lebensmitteluntersachung und Hygiene.2000, 91:567~580

[5] Cottier S, Riquet AM, Feigenbaum A, et al. Identification of potential migrants in organosol varnish by GC-MS and LC-MS [J] Journal of Chromatography, 1997, 771:366~373

Hu Xiangwei

China Food Fermentation Industry Research Institute