Safety Index Setting And Risk Substance Migration Of Food Contact Silicone Rubber And Products

Silicone rubber is widely used in the field of food contact materials due to its stable physicochemical properties,and a national food safety standard for silicone rubber materials and products for food contact is currently being established.This study focuses on the development of The National Food Safety Standard for Food Contact Silicone Rubber Materials and Products,which aims to provide experimental data and a basis for the setting of relevant indicators in this standard.The first three parts of the study focus on the safety indicators and migration of risk substances in food contact silicone rubber,and the fourth part focuses on the selection of oil and grease food simulants for silicone rubber in the establishment of the new standard.The specific studies are as follows.（1）Samples of silicone rubber for food contact were tested for Total volatile organic compounds（TVOC）content and KMn O₄consumption;the samples were screened for residual volatile organic compounds,volatile migration in the water immersion solution obtained from migration tests and migration of metal elements into the 4%acetic acid immersion solution.The results found that54.5%of the samples contained TVOC greater than the German/French reference limit（0.5%）and the KMn O₄ consumption test results for all samples did not exceed the reference limit（10 mg/kg）in the current rubber standard,suggesting recommendations for setting the TVOC and KMn O₄consumption targets.Silicone oligomers,vulcanising agent degradation products and metallic aluminium were all detected in silicone rubber,with cyclosiloxane oligomers and 2,4-dichlorobenzoic acid（vulcanising agent degradation products）being of concern due to their high detection rates and large relative contents.（2）The migration of cyclosiloxane oligomers D4-D9 to 4%acetic acid,10%ethanol,50%ethanol,95%ethanol and isooctane in food contact silicone rubber products was established by gas chromatography triple quadrupole mass spectrometry（GC-MS/MS）.The method for the determination of the migration of these five food simulants was developed and applied to the detection of actual samples.The results showed that the cyclosiloxane oligomers did not migrate to 4%acetic acid or 10%ethanol,the migration to 50%ethanol was less than that to 95%ethanol and isooctane,some silicone rubber samples showed swelling in isooctane and a few samples showed discolouration in 95%ethanol.（3）A high performance liquid chromatography（HPLC）method was developed for the determination of the migration of 2,4-dichlorobenzoic acid into six food simulants,namely water,4%acetic acid,10%ethanol,20%ethanol,50%ethanol and olive oil,in silicone rubber products for food contact;the migration behaviour of 2,4 The migration behaviour of 2,4-dichlorobenzoic acid was investigated.Experiments showed that the migration of 2,4-dichlorobenzoic acid was affected by the number of migration tests,the type of food simulant,migration temperature and time,and suggested that enterprises and consumers should produce and use relevant products appropriately to reduce the migration risk of 2,4-dichlorobenzoic acid.（4）The suitability of silicone rubber grease-based food simulants for food contact was investigated and it was found that when 1,4-diphenyl-1,3-butadiene（DPBD）was used as the model compound,the grease-based food simulants（50%ethanol and olive oil）could not completely cover the migration in the food after calibration according to the current standard.The results before calibration with 50%ethanol were closer to the migration of DPBD in oily foods than those before calibration with olive oil.It is recommended that if 50%ethanol is chosen as the food simulant for silicone rubber,migration compliance should be determined using the uncorrected migration results.