Lecture No. 20

Product Preservation & Speciality Packaging compiled - PBI

contd…. MAP QUALITY CONTROL & QUALITY ASSURANCE

Seal Integrity and Leak Detection of Modified Atmosphere Packaging Products

It goes without saying that it is all useless if the package leaks! Leaks have been a thorn in the

eye of the food industry for a long time and various tests are performed in order to check for

leaks.

Water Bath

Traditionally, the method has been the water bath. The package is pressurised under water, either

by squeezing the package by hand or by establishing a vacuum in the water container. A leak can

then be detected by bubbles escaping through the leak due to overpressure in the package. The

test is often performed with the same frequency as the head space test. A good idea is to run the

leak test first and then subsequently perform the headspace test.

The problem with the water bath method for industrial use (other than being messy and not too

hygienic) is that it is manual and thus it is difficult to repeat the testing conditions. Bubbles being

detected during one test might not be discovered during the next test, even if the leaks are the

same. Of course, the repeatability becomes better if the vacuum in the water tank is under strict

control. Another problem is the discovery of the leak as bubbles from small leaks can be difficult

to see. In other words, the quality of the water bath method highly depends on the person

performing it and tested packages are difficult to reuse.

Trace Gas Leak Detection

Another form of leak testing is the trace gas method, which is performed in a closed, airtight

chamber. This means that if a leak is present and the gas escapes at a certain and precise vacuum,

a gas sensor will now detect the concentration of the trace gas in the chamber. This method is

extremely precise and can detect all relevant micro leaks.

Trace gas leak detection based on the CO2 which is already present in the Modified Atmosphere

Packages makes trace gas leak detection more affordable than adding helium to the packages.

CO2 based leak detection has a number of advantages:

Lecture No. 20

Product Preservation & Speciality Packaging compiled - PBI

Another trace gas method is hydrogen leak testing, however hydrogen is not a standard MAP gas

and therefore gives added costs. Even more important is the fact that the readings of most gas

analysers are affected by hydrogen, which means that it will not be possible to perform a correct

residual oxygen measurement on the package if it contains hydrogen.

Quality Assurance on Flow Packaging Machines (VFFS/HFFS)

On both horizontal and vertical modified atmosphere packaing enabled flow packaging

machines, measurement of the gas composition is essential for ensuring a long shelf life of the

product. At the same time the nature of flow packaging machines is that the packages are flushed

with a high gas volume to ensure the correct gas composition, typically the amount of gas is

between 2-4 times the volume of the package.

10 Advantages/Reasons to install an on-line gas analyser:

1. With an on-line analyser on flow packaging machine one can typically reduce their gas

consumption with 20-30%

2. One can reduce labour costs, due to less manual quality checks of the residual oxygen

3. One can reduce the amount of waste and labour time spent on repacking products

destroyed by manual testing

4. The packaging machine will stop immediately if the gas content is incorrect - which

means that one will avoid costly repacking and reducing waste of packaging material

5. The gas flow to the packaging machine is always adjusted according to the packaging

speed - no need for manual flow adjustments

6. Even if the operator forgets the manual QC check the machine will stop if the residual

gas content is incorrect

7. The residual oxygen level is monitored continuously - this leads to a uniform quality

which again leads to fewer customer complaints

8. Quality assurance helps protect the company brand and customers will return to the best

and most reliable brands. A bad product reputation can travel very fast these days with

the social media.

Lecture No. 20

Product Preservation & Speciality Packaging compiled - PBI

9. The demand for information is on the rise in the EU, the USA and elsewhere. And each

new regulation, such as the traceability requirements, burdens the QC staff with more

paperwork and increases the likelihood of errors. With an on-line gas analyser one can

transfer quality data directly to a PC - which means reduced paperwork.

10. Excess gas on a flow packaging machine will be lead right into the work space

atmosphere and reduce the air quality. A proper gas flow control will reduce the amount

of excess gas in the production area. A high level of CO2 in the work space atmosphere

will lead to headaches and a large number of days lost through sickness