FoodâPackage Interaction Safety - ACS Symposium Series (ACS

Chapter 10

Downloaded by CALIFORNIA INST OF TECHNOLOGY on December 5, 2017 | http://pubs.acs.org Publication Date: September 13, 1991 | doi: 10.1021/bk-1991-0473.ch010

Food—Package Interaction Safety European Views K. D. Woods Waddingtons Cartons Limited, Leeds LS10 3TP, England

Waddingtons Cartons Limited i s the holder in the UK, France and Germany of the Sieferth microwave susceptor patent, and as such this is where our main interest l i e s in the area of food package interactions. As a commercial producer and supplier of susceptor laminate packaging our interest in the safety of the material can be divided into three categories. F i r s t l y , as a responsible company, we are concerned about the health and safety of the public and we therefore needed to assure ourselves that the susceptor material which we supply to our customers possess no threat to the public's health. Secondly we are required to conform to the regulations i n force in the countries to which we supply. This i s somewhat complicated since most of the food packaging regulations were drawn up some time ago and did not foresee susceptor materials, and the associated high temperatures which can be created in the packaging. Finally, we needed to guard against bad publicity which may severely affect the sale of susceptor packaging and the products which are packed in them. Early on there was much speculation on the safety aspect of susceptors because of the relatively high temperatures that are reached under normal conditions of use (i.e., up to 220°C/450°F). This fear has largely died away as an increasing number of investigations have been carried out. Our own susceptor was tested by several people including James River in the USA (with whom we have a technical know how agreement) and the Ministry of Agriculture, Fisheries and Food (MAFF) in the UK. None of the studies indicated that there was any cause for concern. In the mean time much is being done by the European regulatory bodies to produce suitable legislation to cover susceptors. We are cooperating i n this and have become involved i n some of the work, but we can only wait to see what these regulations w i l l be. When the legislation i s produced we expect that our material w i l l conform. 0097-6156/91/0473-0111S06.00/0 © 1991 American Chemical Society Risch and Hotchkiss; Food and Packaging Interactions II ACS Symposium Series; American Chemical Society: Washington, DC, 1991.


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C u r r e n t l y most o f the s a f e t y work has l o o k e d a t the s u s c e p t o r on i t s own. I n the UK many o f the s u s c e p t o r packs on s a l e a r e heated i n the microwave oven a f t e r f i r s t removing a l l a d d i t i o n a l pac k a g i n g and t h e r e f o r e r e q u i r e no a d d i t i o n a l i n v e s t i g a t i o n i n t o i t s safety. There i s though a r e q u i r e m e n t f o r g r e a t e r convenience f o r the food packer and the consumer, t o g e t h e r w i t h a w i s h t o keep c o s t s to a minimum. These f a c t o r s have a l l l e d t o a demand f o r the s u s c e p t o r t o be i n c o r p o r a t e d i n t o o t h e r p a c k a g i n g components Typicall y , the r o u t e employed i s t o window p a t c h a p i e c e o f s u s c e p t o r paper i n t o a paperboard c a r t o n . Window p a t c h i n g i n v o l v e s g l u i n g the s u s c e p t o r t o the c a r t o n d u r i n g the c a r t o n m a n u f a c t u r i n g p r o c e s s . T h i s uses a machine t r a d i t i o n a l l y employed t o s t i c k c l e a r f i l m o v e r a p e r t u r e s i n the c a r t o n , so p r o d u c i n g a d e c o r a t i v e window i n the c a r t o n , hence the term window p a t c h i n g . The i n t e g r a t i o n o f the s u s c e p t o r i n t o the pack can p o t e n t i a l l y s u b j e c t the v a r i o u s components i n the pack t o the h i g h temperatures g e n e r a t e d by the s u s c e p t o r . N o r m a l l y these components i n c l u d e window p a t c h a d h e s i v e , c a r t o n b o a r d and i n k s . Other a d h e s i v e s used to h o l d the c a r t o n t o g e t h e r may a l s o be exposed t o h i g h e r than normal t e m p e r a t u r e s , a l t h o u g h s i n c e these tend n o t t o be i n d i r e c t c o n t a c t w i t h the s u s c e p t o r , the temperatures w i l l be s i g n i f i c a n t l y l o w e r than the 200°C produced by the s u s c e p t o r . W h i l e the chances of any u n d e s i r a b l e s u b s t a n c e s b e i n g produced and t r a n s f e r r i n g t o the f o o d i s low, t h i s a r e a needs t o be i n v e s t i g a t e d . S p e c i a l window p a t c h a d h e s i v e have been developed and t e s t e d by a number o r a d h e s i v e m a n u f a c t u r e r s Less development has been undertaken on the i n k s . Many o f the i n k s used f o r non-microwave a p p l i c a t i o n s can be shown t o c o n t a i n o r g a n i c pigments w h i c h i n c o n t a c t w i t h s u s c e p t o r s i n the microwave oven s u b l i m e . W h i l e the ovens a r e w e l l v e n t i l a t e d and the s m a l l q u a n t i t y o f i n k i s on the o u t s i d e o f the pack i t i s u n l i k e l y t h a t any o f the pigment w i l l t r a n s f e r t o the f o o d These pigments a r e e a s i l y a v o i d e d by s p e c i f y i n g n o n - s u b l i m a b l e pigments t o the i n k m a n u f a c t u r e r , so removing the p o t e n t i a l r i s k . Other v o l a t i l e s may a l s o be g i v e n o f f from the i n k s and these w i l l depend upon t h e i r type and f o r m u l a t i o n . The c h o i c e o f board used f o r the c a r t o n a l s o p r e s e n t s a d d i t i o n a l problems. C a r t o n boards have a s u r f a c e c o a t i n g t o g i v e a good smooth s u r f a c e s u i t a b l e f o r p r i n t i n g . The f o r m u l a t i o n s o f these a r e c l o s e l y guarded by the board m i l l s s i n c e the c o a t i n g performance i s one o f the main d i f f e r e n t i a t i o n s between a l t e r n a t i v e boards. Suscept o r s , s i n c e they a r e u s u a l l y u n p r i n t e d , a r e produced u s i n g uncoated b o a r d s , but i n p r i n t e d c a r t o n s the c o a t i n g s a r e a n o t h e r unknown commodity a t s u s c e p t o r t e m p e r a t u r e s . In the USA o n l y two types o f c a r t o n b o a r d a r e g e n e r a l l y a v a i l a b l e , S o l i d White Board and Chipboard Chipboard i s produced from waste paper and i s c l e a r l y u n s u i t a b l e f o r use i n c o n t a c t w i t h s u s c e p t o r s , s i n c e no guarantees can be g i v e n as t o what s u b s t a n c e s may be c o n t a i n e d i n the f i n i s h e d board. I n the UK and Europe the c h o i c e i s much g r e a t e r w i t h the a v a i l a b i l i t y o f F o l d i n g Box Boards (FBB) which a r e s i g n i f i c a n t l y cheaper than e q u i v a l e n t S o l i d White Boards. FBBs a r e produced from one o r more types o f p u l p . The p u l p s can be s p l i t i n t o f o u r t y p e s , M e c h a n i c a l , Thermo-Mechanical (TMP), Chemo-Thermo-Mechanical (CTMP) and S o l i d B l e a c h e d S u l p h a t e (SBS) pulps. SBS i s e f f e c t i v e l y pure c e l l u l o s e f i b r e , a l l o t h e r components o f the wood (about 50%) h a v i n g been removed i n the p u l p i n g

Risch and Hotchkiss; Food and Packaging Interactions II ACS Symposium Series; American Chemical Society: Washington, DC, 1991.


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p r o c e s s . The o t h e r p u l p i n g p r o c e s s e s remove l e s s o f the wood's nonc e l l u l o s e components, such as l i g n i n , r e s i n a c i d s , f a t t y a c i d s , t u r p i n o i d compounds and a l c o h o l s . T y p i c a l y i e l d s from these p u l p i n g p r o c e s s e s v a r y from 6 5 % t o 95%. A g a i n these a d d i t i o n a l compounds pose a p o t e n t i a l r i s k . S i n c e a l l the boards a v a i l a b l e v a r y because o f d i f f e r e n t c o a t i n g s and d i f f e r e n t c o m b i n a t i o n s o f p u l p s , we c o n s i d e r i t w i s e t o t e s t each board we w i s h t o use i f i t has not p r e v i o u s l y been analysed. While t h e r e i s p r o b a b l y l i t t l e r i s k from a l l these p o t e n t i a l problems we c o n s i d e r t h a t a l l i n t e g r a l s u s c e p t o r packs s h o u l d be c a r e f u l l y c o n s i d e r e d , and any a n a l y t i c a l work thought n e c e s s a r y c a r r i e d out b e f o r e the p r o d u c t i s p l a c e d on the market. Below i s a b r i e f d e s c r i p t i o n o f some o f work t h a t has been c a r r i e d o u t on o u r packs. Research Overview and Results In the f i r s t s t u d y the p a r t i c u l a r pack o f i n t e r e s t was a Microwave C h i p s (French F r i e s ) c a r t o n . T h i s c o n s i s t e d o f a t o p l o a d c a r t o n p r i n t e d w i t h UV i n k s and v a r n i s h , w i t h a r e c t a n g l e o f s u s c e p t o r window patched on t o t h e base o f t h e c a r t o n . A f t e r f i l l i n g t h e c a r t o n w i t h c h i p s , the c a r t o n i s c l o s e d w i t h s i d e seams o f w a t e r based and h o t - m e l t a d h e s i v e s , l o c a t e d a p p r o x i m a t e l y a t h i r d o f t h e way up the s i d e w a l l s . To answer some o f the q u e s t i o n s about the s a f e t y o f the m a t e r i a l s , work was commissioned t o be c a r r i e d out a t the Leatherhead Food Research A s s o c i a t i o n . The work was funded by the f o o d m a n u f a c t u r e r , LMG Mardon (a s u s c e p t o r l i c e n s e e i n the UK) and Waddingtons C a r t o n s Limited. The work was c a r r i e d out i n two p a r t s . F i r s t the l i k e l y v o l a t i l e s were a n a l y s e d i n a s i m p l i f i e d system under "worst c a s e " c o n d i tions. The u s e o f a s e m i - s o l i d f a t s i m u l a n t (see l a t e r ) gave s l i g h t l y h i g h e r s u s c e p t o r temperatures than w i t h a c t u a l f o o d and so s a t i s f i e d the "worst c a s e " c r i t e r i o n r e q u i r e d . When these compounds had been i d e n t i f i e d , a c t u a l p r o d u c t , which had been microwave heated i n the complete c a r t o n was t e s t e d t o see i f these compounds d i d i n f a c t m i g r a t e i n t o the c h i p s . Temperature measurements a t the g l u e seams had r e c o r d e d tempera t u r e s o f between 70°C and 112°C, but measurements o f the i n t e r n a l s u r f a c e o f the s i d e w a l l s had shown a maximum temperature o f 131°C. T h e r e f o r e i n o r d e r t o be c e r t a i n t h a t we had a worse case s i t u a t i o n a temperature o f 140°C was c o n s i d e r e d t o be the temperature s u i t a b l e f o r a n a l y s i s o f compounds which may a r i s e from the a d h e s i v e s d u r i n g h e a t i n g and may then t r a n s f e r t o the f o o d p r o d u c t . The v o l a t i l e compounds g i v e n o f f by t h e g l u e s were a n a l y s e d u s i n g gas chromatograph/mass s p e c t r o m e t r y (GC/MS). A l t h o u g h d i f f i c u l t t o i d e n t i f y p r e c i s e l y from t h e i r mass s p e c t r a many o f the peaks from t h e h o t m e l t a d h e s i v e appeared t o be o f n a t u r a l o r i g i n and t y p i c a l o f compounds which would be g i v e n o f f by p l a n t e x t r a c t s . The r e s i n used i n the hot m e l t a d h e s i v e i s a d e r i v a t i v e o f limonene, t h e main hydrocarbon f r a c t i o n o f many e s s e n t i a l o i l s , and i s the l i k e l y s o u r c e o f these compounds. The o t h e r components o f the p a c k a g i n g were t e s t e d by microwave heating i n a sealed vessel together with a semi-solid f a t simulant



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w h i c h had been developed a t the M i n i s t r y o f A g r i c u l t u r e , F i s h e r i e s o f Food (MAFF) i n the UK. The s i m u l a n t was then e x t r a c t e d u s i n g L i c h e n s - N i c k e r s o n a p p a r a t u s , w h i c h g i v e s good r e c o v e r y o f compounds w i t h a v o l a t i l i t y range s u i t a b l e f o r GC. The r e s u l t a n t e x t r a c t was then a n a l y s e d by GC/MS. E a r l i e r work w i t h the MAFF s e m i - s o l i d f a t s i m u l a n t had shown good c o r r e l a t i o n between the s u s c e p t o r s temperature profile in c o n t a c t w i t h 100g o f s i m u l a n t ( i n t h i s c a r t o n ) and w i t h 100g o f c h i p s (both i n a 650W oven w i t h n e i t h e r i n a s e a l e d v e s s e l ) . The s i m u l a n t temperature were s l i g h t l y higher. These temperatures were r e c o r d e d w i t h an e a r l i e r f o r m u l a t i o n s i m u l a n t than t h a t a c t u a l l y used i n t h i s t e s t , but the temperatures o b t a i n e d were not e x p e c t ed t o be r a d i c a l l y d i f f e r e n t . The s i m u l a n t used c o n s i s t e d o f 35% w a t e r , 25% o l i v e o i l and 40% diatomaceous e a r t h , i . e . , C e l i t e . The t r i a l s were c a r r i e d o u t i n a 600W oven. 100g o f the s i m u l a n t t o g e t h e r w i t h the t e s t sample were heated f o r A minutes on f u l l power i n a s e a l e d g l a s s v e s s e l j u s t l a r g e enough f o r the c a r t o n t o be p l a c e d i n s i d e . I n o r d e r t o o b t a i n some i d e a o f where any v o l a t i l e components d e t e c t e d had o r i g i n a t e d from, f o u r t e s t s were c a r r i e d o u t . These were:a) B l a n k - 100g o f s i m u l a n t p a t c h taped t o o u t s i d e .

inside

glass

vessel with

susceptor

b) S u s c e p t o r o n l y - s u s c e p t o r p a t c h i n s i d e v e s s e l , s i m u l a n t packed around i t (50g above, 50g b e l o w ) . c) U n p r i n t e d c a r t o n - i n c l u d i n g s u s c e p t o r and window patched sive. 100g o f s i m u l a n t i n s i d e c a r t o n .

adhe-

d) P r i n t e d c a r t o n - as c) above but c a r t o n p r i n t e d w i t h UV i n k s and varnish. B e f o r e the s i m u l a n t was e x t r a c t e d , 1ppm o f d e u t e r a t e d benzene and naphthalene were added as s t a n d a r d s . GC/MS a n a l y s i s showed some i n c r e a s e i n c o n c e n t r a t i o n o f compounds found i n the b l a n k t o g e t h e r w i t h the appearance o f a number o f a d d i t i o n a l compounds. The conc e n t r a t i o n o f these compounds was e s t i m a t e d t o be i n the range o f 0.1 t o 5ppm. Compounds w i t h i n c r e a s e d c o n c e n t r a t i o n a r e l i s t e d below:Heptane Pentan-1-ol Octane Hexanol Heptanal Heptenal A l k e n e s (3) Alkane Methyl F u r f u r a l A l k y l Furan

Octanal P r o p y l Furan O c t e n a l Isomer O c t e n o l Isomers (2) Nonanal Nonenal Isomer D e c e n a l Isomers (3) D e c a d i e n a l Isomer (2) A l k y l Cyclohexenol ? A l k y l Cyclohexenone ?


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A d d i t i o n a l compounds i d e n t i f i e d were:Furfural D e c a t r i e n a l Isomer? ^15 24 S e s q u i t e r p e n e Benzophenone


H

S u s c e p t o r , P l a i n and P r i n t e d c a r t o n S u s c e p t o r , P l a i n and P r i n t e d c a r t o n P l a i n and P r i n t e d c a r t o n P r i n t e d Carton only

Benzophenone i s a p h o t o i n i t i a t o r used i n UV i n k s and c l e a r l y t h i s i s where i t o r i g i n a t e d . Having i d e n t i f i e d t h e above compounds w h i c h c o u l d p o t e n t i a l l y be t r a n s f e r r e d t o t h e f o o d , t h r e e d u p l i c a t e t e s t s were c a r r i e d o u t on t h e a c t u a l p r o d u c t t o e s t a b l i s h i f any o f these compounds d i d i n f a c t t r a n s f e r t o the c h i p s . The complete packs, i n c l u d i n g 100g o f c h i p s were cooked i n a 650W oven a c c o r d i n g t o t h e h e a t i n g i n s t r u c t i o n s g i v e n f o r t h e p r o d uct, i . e . , 3 minutes a t f u l l power f o l l o w e d by 1 minute s t a n d i n g . The f r e n c h f r i e s were then s p i k e d w i t h 1ppm d e u t e r a t e d naphthalene and e x t r a c t e d u s i n g L i c h e n s - N i c k e r s o n apparatus i n t o d i e t h y l e t h e r . T h i s e x t r a c t was then a n a l y s e d as f o r t h e s i m u l a n t e x t r a c t s , by f u l l scan GC/MS. Many compounds seen i n t h e s i m u l a n t experiment were found i n t h e e x t r a c t s from t h e c h i p s , b u t a t a much l o w e r l e v e l . The c o n c e n t r a t i o n o f these compounds were a l l e s t i m a t e d t o be below 1ppm. Of t h e a d d i t i o n a l compound n o t found i n the s i m u l a n t b l a n k b u t d e t e c t e d i n t h e o t h e r s i m u l a n t t e s t s o n l y t h e d e c a t r i e n a l isomer and benzophenone were found i n t h e c h i p e x t r a c t . T h i s suggests t h a t f u r f u r a l and t h e s e s q u i t e r p e n e , w h i c h were n o t p r e s e n t i n t h e c h i p e x t r a c t , had been d e r i v e d from t h e o l i v e o i l used i n t h e s i m u l a n t (and t h e r e f o r e was n o t c o n s i d e r e d a cause f o r c o n c e r n ) . The c o n c e n t r a t i o n o f benzophenone was c a l c u l a t e d by comparison w i t h a s t a n d a r d o f a u t h e n t i c compound. The benzophenone l e v e l found (0.2 - 0.3 ppm) i s below t h e l i m i t f o r s p e c i f i c m i g r a t i o n proposed by European Community r e g u l a t i o n s , and as such s h o u l d n o t p r e s e n t a problem. The c o n c e n t r a t i o n o f d e c a t r i e n a l isomer was a l s o below 1ppm. These r e s u l t s on t h e a c t u a l pack s u p p o r t t h e view t h a t t h e s i m u l a n t r e p r e s e n t e d a "worst c a s e " compared t o a c t u a l u s e . None o f t h e components g i v e n o f f from t h e g l u e s were found i n the r e a l food a n a l y s i s , t h e r e f o r e , these a d h e s i v e s can be c o n s i d e r e d s a f e f o r n o n - d i r e c t c o n t a c t w i t h t h e food when p o s i t i o n e d away from the s u s c e p t o r . While a t o t a l assurance on s a f e t y i s n o t p o s s i b l e , g i v e n t h a t the experiments c a r r i e d o u t c a n o n l y d e t e c t compounds w h i c h a r e amenable t o a n a l y s i s by GC/MS and a t around t h e ppm l e v e l , t h e t e s t r e s u l t s found n o t h i n g t o worry about from a s a f e t y p o i n t o f view. A s e p a r a t e study l o o k e d a t a c a r t o n b o a r d proposed f o r use w i t h a window patched c a r t o n . The proposed c a r t o n b o a r d was a f o l d i n g box board (FBB) c o n s i s t ing o f f i v e p l i e s . The back p l y i s m a i n l y m e c h a n i c a l p u l p w i t h a



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s m a l l p r o p o r t i o n o f c h e m i c a l p u l p . The t h r e e m i d d l e p l y s are p r o duced from m e c h a n i c a l pulp w i t h the top p l y b e i n g produced from chem i c a l p u l p . T h i s top s u r f a c e i s then c o a t e d t o g i v e a good s u r f a c e for printing. The s u s c e p t o r pack i n c o r p o r a t i n g t h i s board was then t e s t e d a t our customer's r e s e a r c h c e n t r e u s i n g the f o l l o w i n g method:A 5cm x 6cm p i e c e o f the s u s c e p t o r l a m i n a t e / window p a t c h a d h e s i v e / FBB p l a c e d i n a s e a l e d g l a s s v i a l was heated i n a 600W microwave oven f o r 10 m i n u t e s . The headspace i n the v i a l was then a n a l y s e d u s i n g GC/MS. The c o n d i t i o n s chosen ( i . e . , 10 minutes i n a 600W oven w i t h o u t any a d d i t i o n a l l o a d ) a r e based on the time r e q u i r e d f o r the p r o d u c t t o be heated. I t i s r e c o g n i s e d t h a t these c o n d i t i o n s a r e f a r more s e v e r e than i n p r a c t i c e where the f o o d l o a d i s p r e s e n t , but these more s e v e r e t e s t c o n d i t i o n s were c o n s i d e r e d v a l i d f o r the purpose o f the t e s t s , t h a t i s t o determine i f the pack i s s a f e even i n the w o r s t case s i t u a t i o n . The t e s t on the s u s c e p t o r paper l a m i n a t e / window p a t c h adhes i v e / c a r t o n b o a r d composite showed t h a t benzene was g e n e r a t e d a t l e v e l s o f 0.05 ug/cm . The benzene c o u l d have o r i g i n a t e d from e i t h e r the s u s c e p t o r l a m i n a t e , the window p a t c h a d h e s i v e o r the f o l d i n g box board. F u r t h e r t e s t s were t h e r e f o r e i n i t i a t e d t o d e t e r mine where t h i s benzene had i n f a c t come from. A l a r g e q u a n t i t y o f work had been c a r r i e d out p r e v i o u s l y on the susceptor laminate. None o f t h i s had shown benzene c o u l d be p r o duced on h e a t i n g . T h i s suggested t h a t the s u s c e p t o r was not the source. T e s t i n g the s u s c e p t o r l a m i n a t e a l o n e under the same c o n d i t i o n s confirmed t h i s . The window p a t c h a d h e s i v e was next t o be r u l e d o u t . 5cm x 6cm p i e c e s o f g l u e d and non-glued s u s c e p t o r / FBB were t e s t e d . These both produced s i m i l a r l e v e l s o f benzene which showed t h i s was n o t the s o u r c e . These r e s u l t s p o i n t e d s t r o n g l y t o the board b e i n g the source o f the benzene. S i n c e w i t h o u t the s u s c e p t o r , the FBB a l o n e w i l l not heat t o the r e q u i r e d temperatures i n a microwave oven, the above t e s t c o n d i t i o n s c o u l d not be a p p l i e d . To c o n f i r m t h a t the FBB was indeed the s o u r c e a v i a l c o n t a i n i n g a 5cm x 6cm sample o f the FBB a l o n e was heated i n a m u f f l e f u r n a c e to 200°C f o r 2 minutes and the r e s u l t i n g headspace a n a l y s e d . The presence o f benzene c o n f i r m e d t h a t the benzene was a p r o d u c t o f the p y r o l y s i s o f the FBB. The r e s u l t s o f the benzene d e t e r m i n a t i o n are l i s t e d i n t a b l e 1. 2

Table 1.

Benzene l e v e l s generated by package components

Susceptor/window adhesive/FBB S u s c e p t o r / 9 0 % window adhesive/FBB S u s c e p t o r laminate/FBB Susceptor laminate only FBB o n l y (heated t o 200°C) It produced

2

0.05 ug/cm 0.07 ug/cm 0.06 ug/cm ND (

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