How to avoid migration: Do we need better barriers? Dr. Thomas Gude

Transcription

1 How to avoid migration: Do we need better barriers? Dr. Thomas Gude Mar 2016

2 Optimum Packaging Design

3 Packaging specification drafting

4 Dimensioning of food packaging materials

5 Optimum use of material

6 Classic Barrier Materials Design of Barrier Functionality Extending Functionality Permeation of Gases like: - Oxygen - Water steam - Carbon dioxide - Nitrogen -... Radiation: - visible light - ultraviolet radiation Permeation of Contaminants like: - Plasticizer - Printing Inks - Mineral oil -... Oxygen Permeability (cm 2 /m 2 d bar) Water Vapour Permeability (g/m 2 d) at 23 c, 85% r.h..

7 Functionality Barrier

8 Properties of food packaging materials

9 Interaction between packaging, food and environment

10 EU: VO 10/2011 Functional Barrier D P Migrant K FB,F Migrant D P K FB,F Migrant D P K FB,F D P Migrant K FB,F - Consideration 27 Kunststoff FB Kunststoff FB In such a plastic multi-layer material or article, layers may be separated from the food by a functional barrier. This barrier is a layer within food contact materials or articles preventing the migration of substances from behind that barrier into the food. Behind a functional barrier, nonauthorised substances may be used, provided they fulfil certain criteria and their migration remains below a given detection limit. Taking into account foods for infants and other particularly susceptible persons, as well as the large analytical tolerance of the migration analysis, a maximum level of 0,01 mg/kg in food should be established for the migration of a non-authorised substance through a functional barrier. Substances that are mutagenic, carcinogenic or toxic to reproduction should not be used in food contact materials or articles without previous authorisation and should therefore not be covered by the functional barrier concept. Simulanz / Lebensmittel Kunststoff FB Simulanz / Lebensmittel Simulanz / Kunststoff FB Lebensmittel Simulanz / Lebensmittel

11 Concept of Functional Barrier Permeation, Diffusion, Coefficients x Permeation: Q = P/x Q: Permeation P: Permeation coefficient x: thickness of Barrier Permeation coefficient: P = D x S D: Diffusions coefficient; how fast a molecule is moving in the polymer? S: Solubility; how much molecules are solved in the solution? Source: adopted from Dr. Noller, K., Permeation durch Packstoffe bei Lebensmittelverpackungen und Herstellung von Barrierefolien, Fraunhofer Institut für Verfahrenstechnik und Verpackung, Vortrag Kunststoffe-Packaging, Fellbach 2008

12 Concept of Functional Barrier Lag Time, shelf life of Food a functional barrier is a multilayer packaging structure, in which one layer blocks/delays the migration of migrant through the packing into the food. m: Mass Transfer D: Diffusion coefficient of migrant K: Partioning coefficient of the migrant how much substance is in the food? t : lag time b t b Requirement for functional Barrier given, if: t b > t Shelf life of food Source: Pieringer, O., et. al.: Plastic Packaging, Whiley-VCH, Weinheim, 2008 S. 350

13 What is a functional barrier

14 Concept of Functional Barrier Interferences in barrier layer Pinholes. x Defect relative high to thickness: r Q = P n π r 2 x Q: Permeation r: Radius of Defects P: Permeation coefficient n: amount of Defects x: Barrier thickness x Defect relatively small to thickness: Q = 3,7 P n r Source: Langowski, H., Permeation of Gases and Condensable Substances through Monolayer and Multilayer Structures in Plastic Packaging, Piringer O., Baner l., Second Edition, Wiley-VCH, Weinheim 2008, S. 309.

15 Behavior of Barriers Pure Gas phase: Small defects, no problem condensate, liquid Each defect leads to significant migration Source: Animation by Dr. Hermann Seyffer, BASF SE 2011

16 Concept of Functional Barrier Interferences in barrier layer, example metallised BoPP-Foil BoPP-Foil metallised with 40nm Aluminium Coating-Defects white dots Source: Dr. Noller, K., Permeation durch Packstoffe bei Lebensmittelverpackungen und Herstellung von Barrierefolien, Fraunhofer Institut für Verfahrenstechnik und Verpackung, Vortrag Kunststoffe-Packging, Fellbach 2008

17 Why we need Barriers? Recycling of paper and board is not the clean process expected for food packaging material Neither with regard to hygiene..

18 Where necessary? Barriers for dry food, which is stored for long time at room temperature Exception: salt for cooking Party plates made of recycled cardboard Not necessary for patisserie, cakes etc., which are only short time in contact Not necessary for fruits and vegetables in trays, as well as for eggs open: short time stored products in card boxes, which were heated, i.e. Pommes)

19 not avoid migrating of substances NIAS in FCM generally NIAS in Plastic NIAS in Coatings NIAS in Paper Mineral oils: MOSH MOAH POSH

20 Safety versus Sustainability Safety of the many and varying migrating substances cannot be realistically be verified (Unprotected) recycled paperboard does not fulfil basic legal requirements: safety However: recycling of paper and board is important because of sustainability use of resources

21 Obstacles Lacking of rules/specifications clarifying what is sufficient barrier property Producers of packaging need criteria to find economic solutions satisfying such as for functional barriers Customers (food industry) want to know whether an offered product is acceptable and causes no issues The most toxic migrating substance and their concentrations in recycled paperboard must be considered unknown A sustainable solution (e.g. barrier) should be satisfactory for all migrants, including the unknowns Reduction should avoid the investigation of all contaminants Need for a Guideline

22 Barrier Tests - Possibilities: Modelling by using Diffusion constants Less data for good barriers Bad spots are not considered Determination of the lag time Analysis of problematic substances known substances (however majority is not known) Would consider quality of cardboard Analysis of Surrogate substances Long term storage tests Calibration for lab accelerated lab test For compliance migration into food is relevant

23 Tests: Principles Test on two aspects: 1. Surface migration through barrier Choice of barrier materials; minimum layer size Migration through local defects (Pinholes; Integrity of Barrier layer) For long term most important! 2. Surrogate components: to be defined conventional test Similar volatility for comparison Difficult calibration (unknown problematic substances) No linear relation! Lag-Phase (Break-through barrier) Long Lag-Phase (slow migration through barrier) slow slope after break-through Bad spots change curves Migration Lag-Phase Time

24 Quick Test 1: Diehl, Seyffer, Blum (BASF) Quick test for industry; Acceleration by using small molecule: hexane Gravimetric determination of loss on weight by migration through barrier Test over 24 h only Swelling of barrier? Pressure difference: Pores have an influence

25 Quick Test 2: SQTS Glass cell swelling can be observed Calculation of Permeation in [g/m²d] Loss in Weight Quelle: Piringer, O., A Uniform Model for Prediction of Diffusion Coefficients with Emphasis of Plastic Materials in: Plastic Packaging, Piringer O.,Baner l., Second Edition, Wiley-VCH, Weinheim 2008, S. 189.

26 Barrier-Quick Tests Very quick first overview relative comparisons possible Homogeneity of material is key «very quick» Single determination Much better: min. 3-fold determination Only Gas phase-transfer Disadvantage: Is Hexane the ideal model substance; for hydrocarbons might be useful What about other substances with migration potential

27 Barriers: 2D and 3D Tests 2D Test 3D Test Sample 100% value )in Tenax in open sieve Gravex Oil in separate Container

28 2D- Test: Welle/Ewender Static Donor, receptor side Gas flow for transfer in a trap F. Welle, Sept in Berlin

29 2D-Test: Three technical solutions Solutions: Internal bags with a barrier layer Coating of the internal surface of paperboard with a barrier Adding an adsorbent to the paperboard to prevent release, i.e. charcoal Projects Swiss Packaging Institute Joint Industry Group (SVI-JIG) Two Projects: Barriers in internal bags published in 2016 Coated paperboard - started

30 «Standard Test» Tenax 10 d/40 C Cardboard Barrier foil Tenax old convention, never validated for long time contact For assessment of human health still values in food are important In case of problems, simulation useless

31 Acceleration (3 years storage?) How to accelerate? Thinner layer (proportional to Quadrat!), Problem: Integrity Temperature: can change material (Glass transition) Smaller surrogate molecules Acceleration according to Arrhenius with activation energy of 80 kj/mol (PIM) 40 C instead of 25 C: Factor C instead 25 C: Factor 30 3 years= 5 weeks at 60 C Clear statement if barrier is tight (<1 % Break through), not clear, if untighten. 10 d at 40 C is not a suitable test to simulate l ong time storage

32 Test Conditions Surrogate substances applied to recycled paperboard (donor) 3 Surrogate substances with wide polarity range n-heptadecane (C17; Mineral oil) Dipropylphthalate (DPP) 4-Methylbenzophenone (MBP) Donor wrapped in aluminium foil and tightly fixed to barrier Monitoring of breakthrough by absorption onto Silicon paper (receptor) Periodically a piece is cut away and analysed by GC/MS/FID

33 2D- Version: SVI Surrogates as Donor Silicon -Foil as Acceptor Donor package Spacer Tight cover Barrier Acceptor Donor (colored with Sudan red) Alumina foil Barriers against the migration of mineral oil from paperboard food packaging: Experimental determination of breakthrough periods. K. Fiselier, K. Grob Packaging Technology and Science 25 (2012)

34 Silicone paper Barrier Donor Spacer Adhesive foil

35 Test Criterion Breakthrough below 1% is accepted related to starting concentration Assumptions: Mass ratio paperboard/food: ~10 (varies from 1:4 to 1:25) Complete migration from paperboard into food 10 µg/kg in food from 100 µg/kg in paperboard

36 The Goal of the Guideline Only relative results are yielded Comparability of results is increased when using the guideline Each barrier has its entitlement always related to the shelf life of the food Categorisation of materials will be shown The user (buyer) can better decide what to by if results are comparable The developer of barriers can demonstrate their suitability compared to other solutions Important: the guideline will distinguish between good and bad barriers

37 Results Some results for foils, which could be of interest for inner bags; Assessment in weeks until 1 % migration of one of the surrogates: Everything has to be tested for own application!!!

38 2D versus 3D-Testing Guideline is based on 2-dimensional testing (2D) However, no packaging is 2D causing problems: Closure of boxes, foils sealing/folding areas Pinholes per se or by damage Set-off Etc. So 2D-test are the starting point, but real tests (with food) are necessary 3-dimensional Tests (3D) 2D Test 100% value in Tenax in open sieve 3D Test Gravex Oil in separate Container Sample

39 3D-Barriers: SQTS 1. Folded coated card boxes 2. Migrating substances outside 3. Inner side Tenax, possibly in a net

40 The ultimate barrier tests an example Pasta in selling packaging as well as in transport packaging Transport packaging made of recycled Cardboard Tenax is placed in empty bags Everything is wrapped in alufoil and stored at RT and at 18d 60 C 1st step: Analysis in Tenax Screening MOSH/MOAH, Phthalates (DIBP), ATBC, DINP «unknowns» molecular formula is known 2nd step: Analysis in stored Pasta for marker substances after 18d 60 C low findings «Unknowns» however under evaluation

41 Good Experiences 3D-Tests were/are successfully used with different materials: Coffee capsules in cardboard cover Chocolate in plastic-bags for intermediate storage Pasta in Recycling cardboard (direct and in bags) Contaminations during production, i.e. shrinking tunnels etc. Further applications

42 Future Projects

43 Paperboard with barrier Problems with set-off when stacking Problems with spiking surrogate substances Migration through paperboard follows different rules then plastic 3D- problems Recycling problems

44 Summary

45 Take Home Message Barriers, if they are able to avoid migration within shelf life of product, are best packaging solution to increase food safety As a starting point comparable data on testing for 2D-barrier behaviour are needed based on the SVI guideline Advantages for seller and buyer of barrier It depends on the risk classification of the packaging/food combination, if a 3D-barrier test is required 3D-barrier testing with real food and marker substances might be the best option