Yearbook 2013/2014 - ehedg

European Hygienic Engineering & Design Group
Aspects of compounding rubber materials for contact
with food and pharmaceuticals
Equipment and equipment components made with rubber materials that come into contact
with food in processing lines must comply with regulatory requirements such as FDA’s Code
of Federal Regulations (CFR), 3-A Sanitary Standards, and US Pharmacoepia (USP) Class VI
standards. It is also necessary to consider the working conditions in which the gasket will be
used, including what products are produced, the cleaning and sterilization agents utilized in
those processes, and temperatures or other factors that may impact the efficiencies of equipment
and components throughout the process line. In order to maintain a high hygienic standard, a
very good cleanability of any equipment component with a rubber surface must be achieved and
thorough documentation provided.
Anders G. Christensen, Sales and R&D Director, AVK GUMMI A/S, Mosegaardsvej 1, DK-8670 Laasby, Denmark,
email: avk@avkgummi.dk, www.avkgummi.dk
For many years the food processing industry has referred
to regulatory guidelines and standards that cover the use
and compliance of rubber materials that come into contact
with food. Among these are rules outlined in the U.S. Food
and Drug Administration (FDA) 21 CFR 177.2600 (Rubber
articles intended for repeat use) and the recommendations
of the German BfR XXI (Commodities based on natural
and synthetic rubber) or XV (silicone oil, resins and rubber
requirements). Recently, 3-A Sanitary Standard 18-03 also
has become a de facto standard for many food processing
sectors beyond the dairy industry from which it originates.
This standard not only regulates rubber materials that come
into contact with food, but also the manufacturing conditions,
taking hygienic standards and traceability into consideration.
EN 1935/2004 is an attempt to have a common set of rules
within the European Union (EU). While this regulation is
fully operational with regard to metals and plastics, it is still
a work-in-progress with regard to rubber materials. Until
positive lists of approved ingredients that can be used in
food-contact rubbers and associated testing methods are in
place, the FDA and BfR lists, together with extraction tests,
appear to be the most relevant regulations for food-contact
rubber materials. The member states have now begun to turn
this framework into statutory instruments; however, this may
be at the cost of uniformity and transparency.
Other standards-related developments are affecting require
ments as well. For example, the Danish Ministry
of Food is enforcing the rules of traceability and good
manufacturing practices (GMPs) by means of third-party
inspection of manufacturers’ facilities and process lines. For
pharmaceuticals, normally Class VI under the USP Monograph
88, testing is required. Alternatively, the customer can ask for
in vitro testing, either according to USP Monograph 87 or
International Standards Organisation (ISO) 10993-5.
In addition, end users require documentation for cleanability
of equipment surfaces. Most often this is provided by means
of an European Hygienic Equipment Design Group (EHEDG)
cleanability test of the component in which the rubber part
is present. Except for the geometry and the corresponding
flow profile, the rubber surface is typically the most critical
material when conducting any hygienic test.
For this reason, it is important to consider the affinity between
rubber compounds, products and cleaning agents. Long-term
field studies, such as those conducted by AVK GUMMI, have
been conducted and have led to easy-to-clean formulation of
compounds within the families of ethylene proplene rubber
(EPDM), hydrogenated nitrile (HNBR), fluorocarbon (FPM)
and silicone.
Material performance
In addition to ensuring that food-contact rubber materials
have the relevant approvals, meet appropriate compliance
requirements and have traceability documentation, it
is important to consider material performance. No two
formulations are equal. Even if two manufacturers develop
a compound for the same application, the end user will
experience different performances with each due to
variabilities ranging from the food being produced, the
production line systems, and the level of hygienic operations
in the processing plant and performed on equipment, among
others. The reason for this is shown in Figure 1:
Figure 1. Example comparison of good quality compounds versus
low-cost compounds as recipes for an EPDM 70 Sh A material.