Two Methods for Testing the Safety of Food Packaging Printing

With the rapid development of the world economy, packaging printing presents a splendid scene, and more and more beautiful packaging is produced in printing plants. While enjoying the beautiful packaging, people pay attention to the taste of these beautiful "clothes", especially food packaging. This is a very important issue - the safety of food packaging prints.

The carton pack made of eco-friendly paper or cardboard, such as cigarettes, snack foods, and children's nutritional breakfasts, is adhered to paper after processing by various printing methods. Whether there is any adverse effect on the contents of the package or not Harmful substances transfer food? Especially for the gravure inks that are commonly used in cigarette printing, how can the safety of these ink forms be tested and tested?

We know that printed packaging materials have different degrees of odor, depending on the printing method used and the composition of the ink. How to evaluate these odors? The first thing that should be explained here is that what we emphasize is not what the smell it is emitting is, but the effect of the packaging material that is formed after printing on the contents of the package. We hope that packaging will have as little impact on the smell and taste of its contents as possible.

As we all know, taste and smell are chemical sensations, and their stimulatory effects are the result of biomolecular reactions. Scientists have shown that different parts of our tongues produce acid, sweet, bitter and salty taste effects, and our sense of smell is more sensitive, we can quickly smell the nuances of nuances, but at the same time, the nose is also prone to fatigue. Instead of continuing work, it is generally recommended that perfumers do not continuously identify more than three odors. So, what is the standard for how to detect the odor of packaging prints?

This article briefly introduces several testing methods used by the German printing industry for reference.

I. Gas chromatography analysis

Gas chromatography analysis is widely used in the production of gravure packaging materials.

The content of residual solvents and other odors on the printed package can be objectively determined by gas chromatography analysis. During GC analysis, the gas passes through a separation column and is measured by the detector. Even a small amount of gas can be detected. Flame ionization detector (FID) is its main detection tool. Connect the detector to a PC to record the time and the amount of gas leaving the separation column. Each free monomer condition can be identified by known fluid color chromatogram comparisons. At the same time, each free monomer content can be obtained by measuring the area of ​​the recorded peak and comparing it with a known volume. In the case of the investigation of unknown monomers in the folding carton, gas chromatography is usually used together with spectroscopy (MS) to identify unknown monomers by mass spectrometry.

In gas phase spectrometry, headspace analysis methods are commonly used to analyze folding cartons. The sample to be tested is placed in a sample vial for heating to vaporize the analyzed monomer and enter the headspace. The subsequent process is the same as the previously described test procedure.

Second, Robinson detection method

The Robinson test is defined in the German standard DIN 10955 "Influence of packaging materials on the taste of test materials". For printing, we are concerned about the effect of solvent residues after ink printing. Therefore, printing houses usually use the modified Robinson test method (MHM) to achieve the purpose of testing.

During the inspection process, the surface of the substrate is printed with an ink volume of 1.5 g/m 2 , and then the printed and packaged finished product, for example, after being placed on chocolate for a certain period of time (approximately one day), is evaluated for the taste of the package. The result is usually divided into 5, etc.: 0: No change in taste; 1; It is difficult to discern changes in taste; 2: There is a slight change in taste; 3; There is a certain change in taste; 4: There is a marked change in taste.

Occasionally, some people also perform tests under actual environmental conditions. For example, the carton is tested under high humidity conditions at 75% RH. The result of this is usually quite different from the method specified in DIN 10955.

The above two methods quantitatively test whether the effect of the ink on the odor and taste of the package after printing of the printed matter is safe through experimental means, thereby providing a clear method for evaluating whether the carton package printing is environmentally friendly and safe. China's printing factories and corresponding departments can refer to foreign advanced detection methods and international standards, and formulate detection methods and standards that are consistent with international standards and meet the production conditions in China, so as to promote the development of printing.

Author/Tang Huiyu Chen Lina

Source: China Packaging