Ensuring quality, safety and security for herbs and spices

Producers are looking at glass containers as an alternative to single use plastics. However, when it comes to sealing glass containers for freshness and security, spices can present specific challenges for companies in the food supply chain.

Demand for spices and exotic flavourings is growing. According to the UK’s Confederation of British Industry (CBI), trends such as healthy living, interest in new tastes, and increasing demand for convenience foods has prompted European imports of spices and herbs to grow at sustained rates of well over six per cent in recent years. Globally, the market for spices is expected to grow by more than five per cent through to 2021.

However, in order to compete in this growing market strict requirements for quality, freshness, food safety and traceability must be met by supply chain companies. For these reasons, as well as an intense focus on sustainability and environmental friendliness, consumers and manufacturers are increasingly turning to glass rather than single use plastic containers. Although PET (polyethylene terephthalate) is gaining ground as a plastic packaging suitable for food, for many such products glass occupies a premier position and its use in these applications is partly responsible for significant increases in the use of glass products across Europe over recent years.

Glass brings with it a perception of quality but also provides better impermeability to oxygen than plastics. This ensures freshness, which is a particularly important quality when it comes to high value and intensely flavourful food products such as herbs and spices. Glass is also easily 6recyclable and inert, making it an ideal choice for spice and herb containers which must ensure compatibility with the challenging ingredients that are typically found in spices and herbs. In particular, food products containing volatile organic components such as the exotic oils or fats found in pepper, nutmeg and cloves can present difficulties for producers when it comes to packaging. In Europe, there are also strict regulatory requirements for food products containing fats or oils that come into contact with plastics.

Securing challenging food products
Although glass packaging offers both consumers and manufacturers a range of benefits, it does however present manufacturers with a number of challenges when it comes to sealing the container. This is particularly the case when the contents being sealed has a high oil or fat ratio.

Herbs and spices are not generic and represent a huge range of products that all have unique chemistries. Oleoresins and other oils within spices such as cloves contain the essential flavour profile of the spice and each may contain hundreds of different constituent complex molecules. The unique qualities of each product means they can respond differently to sealing. The volatile oils and fats found in spices are generally characterised by their ability to penetrate seals, acting as a solvent to break the bonds between the seal and the glass container over time. Without specific mitigation measures, this may eventually cause the seal to fail.

In addition, manufacturers also regularly switch between production line fills. For example, a line packaging cardamom in the morning may be on pepper by the afternoon. For the supply chain, gross variations in product chemistries must be readily accommodated, allowing a single cap and sealing system to be applied across the product range. It is also vital that any approach to sealing is sufficiently robust to protect against leaks which can reduce shelf life, increase product returns and production-line downtimes and consequently drive up costs.

Oil-rich food products are often packaged in glass jars with a costly metal cap and a rubber gasket to ensure a good seal and no leaks. PET heat shrink seals are also used to seal spices in glass containers, however these can slow down the production process and can be difficult to open. Another common method of sealing spices in glass jars is by using an induction liner.

A rapid and low-cost process, induction heat sealing of glass jars is used predominantly for dry goods, such as freeze dried coffee. While quick and usually effective, it can be a problematic approach for certain products, such as herbs and spices, where fats or oils may contaminate the neck of the glass container during the filling process.

The induction heat sealing process
Induction seals are available in one- or two-piece designs, which have different bonding capabilities, and must be applied with the correct balance of pressure, heat and duration to create a perfect seal.

As a highly engineered laminated product, an induction liner seal includes an aluminium foil that is at the heart of the non-contact sealing process. Using powerful magnets, during the sealing process a current is induced in the foil which causes it to heat up and melt a separate sealing layer at a relatively low temperature. This in turn bonds to the neck of the glass container. The aluminium foil also creates an additional oxygen and moisture barrier ensuring a truly hermetic seal to deliver the paramount quality of freshness. Furthermore, it delivers on the requirements for product security by introducing a tamper-evident barrier that allows consumers to easily detect any sign that the packaging may have been opened prior to use.

Induction sealing glass containers
For glass containers induction heat seals require an appropriate adhesive layer between the cap and the rim of the glass in order to form a secure bond. However, creating that bond can be difficult due to the physical and chemical properties of glass product packing. To stop glass containers scratching during their passage along the production line, a hot treatment is used to protect them.

A second cold end treatment is then used to promote lubricity which allows the containers to be corralled for filling or labelling without sticking together. For the induction sealing process to be effective, the heat sealing layer must be able to bond with the cold end treatment. Where spices or other oil containing products are being supplied, this bonding layer must also be resistant to the solvent qualities of volatile oils.

To overcome this, a new proprietary induction heat sealing technology – Selig’s GlassFuzeTM – provides production manufacturers with a system that is highly resistant to the aggressive oils found in spices. As well as ensuring a perfect seal with glass containers and their various cold end treatments, it is also completely compliant with current European food product legislation as it contains none of the paraffinic and microcrystalline waxes that are commonly found in induction liners.

As a result, it can be used to seal foods containing oils and fats with induction heat sealing and offers manufacturers the potential to make significant cost and material savings compared with other current approaches to packaging of herbs and spices. This sealing method offers a six-fold improvement in stability in these kinds of applications.

With such advances in sealing technology, a whole new world of low-cost, long shelf life packaging options are now open to the suppliers of herbs and spices.

Selig is a leading worldwide manufacturer of tamper evident cap and closure lining materials for use across a broad range of applications; such as food and beverage, pharmaceutical, agrochemical, cosmetics and healthcare. Selig’s comprehensive range of both one- and two-piece structures means that they can manage even the most challenging applications with one of their customised aluminium foil/heat seal combination products.