Progress in research on the safety of silicone rubber products in food processing.

Silicone rubber (SR) is widely used in the food processing industry due to its excellent physical and chemical properties. However, due to the differences in SR product production formulas and processes, the quality of commercially available SR products varies greatly, with chemical and biological hazard potentials. Residual chemicals in SR, such as siloxane oligomers and 2,4-dichlorobenzoic acid, are non-intentionally added substances, which may migrate into food during processing so the safe use of SR must be guaranteed. Simultaneously, SR in contact with food is susceptible to pathogenic bacteria growing and biofilm formation, like Cronobacter sakazakii, Staphylococcus aureus, Salmonella enteritidis, and Listeria monocytogenes, posing a food safety risk. Under severe usage scenarios such as high-temperature, high-pressure, microwave, and freezing environments with long-term use, SR products are more prone to aging, and their degradation products may pose potential food safety hazards. Based on the goal of ensuring food quality and safety to the greatest extent possible, this review suggests that enterprises need to prepare high-quality food-contact SR products by optimizing the manufacturing formula and production process, and developing products with antibacterial and antiaging properties. The government departments should establish quality standards for food-contact SR products and conduct effective supervision. Besides, the reusable SR products should be cleaned by consumers immediately after use, and the deteriorated products should be replaced as soon as possible.

Influence of cooking conditions on the migration of silicone oligomers from silicone rubber baking molds to food simulants.

The stability, surface micromorphology, and volatile organic compounds (VOCs) of silicone rubber baking molds (SRBMs) were tested while using the molds under severe conditions: baking at 175 °C, microwaving at 800 W, and freezing at -18 °C. Moreover, migration tests of SRBMs to food simulants (isooctane, 95% ethanol, and Tenax®) at 70 °C for 2 h (accelerated conditions) were performed. The initial total VOCs concentration was 2.53% higher than that recommended by BfR Recommendations on Food Contact Materials. Therefore, the SRBM samples were considered as badly tempered materials, and 18 different types of silicone oligomers were identified during the migration tests. The following percentage of silicone oligomers with a molecular weight lower than 1000 Da in isooctane, 95% ethanol, and Tenax® were detected: 70.7%, 91.8%, and 97.2%, respectively. It has been proven that previous baking treatments effectively reduced the content of silicone oligomers migrating from SRBMs.