What are the barriers in PET bottles?

Polyethylene terephthalate or PET is the most widely used material for packaging various water and beverages. In Slovakia, 85% of non-alcoholic beverages are packaged in PET.

PET started to be mass-produced in the 1990s as packaging in the food industry, and it became very popular with producers because of its low weight and low price – compared to glass bottles.
Health safety is important for consumers, for which barrier properties are an important parameter. There are several types of barriers:

  • UV barrier protects the contents of the PET bottle from UV exposure, which adversely affects light sensitive components of the beverage.
  • CO2 barrier prevents carbon dioxide from escaping from carbonated beverages.
  • O2 barrier protects the product against oxygen entering from the air, which leads to oxidation.

Oxidation is the big enemy of beverages. Why? Because in the process of oxidation, the colour components of the beverage are degraded, and the product loses the characteristic colour of the ingredients, changing into an unnatural colour. By oxidation, aromatic substances change their chemical structure and produce negative and smelly components. Oxidation also has a negative effect on product taste - freshness turns old and oxidized. A whole range of biologically active substances also loses positive effects in the oxidation process, such as vitamin C.

Modern science and technology has come up with a unique solution - the ‘oxi barrier’. This prevents penetration of oxygen molecules into the beverage, and does not negatively affect the beverage. Substances used for oxi barriers can bind oxygen in the PET wall penetration process. They also don’t have negative effects on our bodies in the process of migration. These are organic or inorganic components.

McCarter uses these barrier PET bottles with varying efficiency. They can protect the beverage from oxygen for various time periods, or bind different amounts of oxygen, as required. It is one of several steps to protect beverages and preserve the freshness, i.e. sensory and nutritional parameters.

Ing. Ján Durec PhD