IBD Coffee Break 07/15 - PET Technology

l PACKAGING

Barriers for success How technology keeps beer in PET fresh

By Dan Griffiths

The market for single-trip kegs has increased rapidly in recent times and the PET container has in many ways enabled this growth. But with supply chains increasing in length and complexity, there is an ever greater demand for packaging materials to maintain the freshness and quality of beer for longer. In this article, we will look at the quality issues that have affected PET containers in the past and how the use of innovative barrier mate- rials and construction techniques have given brewers the confidence to package more of their production into this material. History of PET as a beer container PET was first developed in the 1941 at the Calico Printers’ Association Ltd in Manchester, England, in the midst of the second world war. Originally intended for use as a synthetic fibre, the material was destined to find use in a wide range of industries and applications. The first PET bottle was patented in 1973 and rapidly found favour in the carbonated soft drinks market, becoming the container of choice by the early 1980’s. However, despite frequent predictions that the PET beer bottle was about to be- come ubiquitous, the use of PET in this capacity remained stalled, being confined for the most part, to certain high-volume applications. Sporting events, music venues and festivals found a use for PET due to its safety and handling benefits when compared to glass. PET also found a use as a container for alcoholic bever- ages at the lower end of the market, some of which are produced in larger

In addition to providing physical and microbiological protection, any material used for packing beer must have three basic barrier properties; it must prevent the ingress of O 2 , it must prevent the loss of CO 2 and it must provide adequate protection from UV light. On top of this, it must be able to do so without contributing any taints, or removing flavour from the product.

I n the modern era, glass and steel have long been used successfully as primary packaging materials in the beer industry. Glass bottles provide a nearly perfect barrier against gas transfer (issues surrounding clo- sures not withstanding), can be tinted to reduce UV light transmission and they present the product in a highly attractive format for the consumer. Steel kegs, which have the advantage of being highly durable, are likewise impervious to gas, and provide com-

plete protection against UV light. For small pack beer, the shelf- life is often considered to have been exceeded once the dissolved O 2 level has exceeded 1ppm. The imperfect seal formed by glass bottle closures results in an O 2 ingress of between 2.0 and 8.4ppb per day, and so a shelf life of between approximately four and 13 months (Bamforth and Krochta, 2010). Use of an O 2 scav- enging material in the closure can extend this period, to a degree. O 2 pickup by an up-tapped steel keg is much lower, but due to other quality concerns, a shelf life of 90 days is often given. The many advantages that the carbonated soft drinks industry have gained from the switch to polyethyl- ene terephthalate (PET) bottles have not gone unnoticed by brewers. PET containers are light and shatterproof, can be stretch-blown from preforms at the brewery, and offer a greater range of marketing opportunities. To- day there are many options available which provide the handling benefits of PET, while giving an excellent barrier performance.

A PET preform and the stretch blown kegs which are formed from it

1 z Brewer and Distiller International

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