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Interna tional Biodeterioration 24 (1988) 387-392

H ygiene spects o f Packag ing in the Food Industry

H . D a l l y n & D . S h o r t e n

The R & D Division, Metal Box plc , Denchworth Road. W antage, OX I2 9BP, UK

A B S T R A C T

The microbiology o f a fo od can be profou ndly in f luenced by the surrounding

package. The m icroorganisms present on the packa ging m aterial m ay need to

be considered along with those o f the product.

This pape r considers the m icrobial lor a o f the package. I t describes som e o f

the hygiene problem s w hich h ave arisen in a large com pany ma nufacturing

pack aging an d the measures taken to overcome them.

Types o f pac king covered include, me tal containers: paper a nd board;

metal~board composites: plastic pac kag ing m aterials; glass a nd caps. Whilst

much o f the in format ion has been derived rom m an y years o f manufac tur ing

experience, some published data are included to complete the survey.

I N T R O D U C T I O N

T h e p r i m e p u r p o s e o f a n y p a c k a g e i s t o p r e s e rv e t h e q u a l i t y a n d s a fe t y o f

t h e p r o d u c t it c o n t a i n s f r o m t h e t i m e o f m a n u f a c t u r e t o th e t i m e i t is u s e d

b y th e c o n s u m e r . A n e q u a l l y i m p o r t a n t f u n c t i o n is t o p r o t e c t t h e p r o d u c t

f r om b r e a k d o w n i n o t h e r w a y s w h i c h c a n b e p h y s i c a l , c h e m i c a l o r

b i o l o g i c al . B i o l o g i c a l d e g r a d a t i o n m a y b e c a u s e d b y l a r g e r o r g a n i s m s

s u c h a s i n s e c t s a s w e l l a s b y m i c r o b e s .

T h e m i c r o b i o l o g y o f a p r o d u c t c a n b e g r e at ly i n f l u e n c e d b y th e

s u r r o u n d i n g p a c k a g e - t h is m a y b e c o n t r i b u t e d to b y t h e m i c r o b i a l f lo r a

o f t h e p a c k a g i n g m a t e r i a l i ts el f, a s w e l l as b y t h e e f fe c t t h a t t h e p a c k a g e

h a s o n t h e e x i s t in g m i c r o b i o l o g y o f t h e p r o d u c t . T h i s s e c o n d f a c to r w i l l

387

International Biodeterioration 0265-3036/88/ 03.50 1988 E lsev ier Science Pub lishers

Ltd, England. Printed in Great Britain.

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388 H Dallyn D Shorten

i n f l u e n c e t h e c h o i c e o f m a t e r i a l s i n c e i ts b a r r i e r p r o p e r t ie s c a n b e

d e ci si ve in d e t e r m i n i n g t h e n u m b e r a n d t y p es o f m i c r o o r g a n i s m s w h i c h

m a y d e v e l o p o n s to r ag e . T h i s h a s f o r m e d t h e b a s i s o f a n u m b e r o f st u d ie s

a n d s o m e o f t h e s e h a v e b e e n s u m m a r i s e d i n re v ie w s (e .g . D a l l y n &

E v e r t o n , 1 9 7 2; l n g r a m & S i m o n s e n , 1 9 8 0 ; S i n e l l , 1 98 0).

T h e s u b j e c t o f t h i s r ev i e w is th e c o n t r o l o f t h e m i c r o b i a l f lo r a o f th e

p a c k a g i n g m a t e r i a l s o t h a t i ts e f fe c ts o n t h e p a c k a g e d p r o d u c t a r e

m i n i m a l o r o f n o e ff ec t.

T h e h y g i e n e o f p r o d u c t i o n , s u b s e q u e n t h a n d l i n g a n d s t o ra g e

p r o f o u n d l y i n f l u e n c e th e m i c r o b i o l o g y o f t h e f i n i s h e d p a c k a g e a n d t h is

i s i l lu s t r a te d w i t h e a c h o f t h e v a r i o u s t y p es o f p a c k a g i n g .

M E T A L C O N T A I N E R S

T h e m a n u f a c t u r e o f m e t a l c o n t a i n e r s i n v o lv e s h e a t c u r i n g p ro c e s s es

w h i c h r e s u l t i n s t e r i l e s u r f a c e s . E v e n w h e r e m e t a l s u r f a c e s c o m e i n t o

c o n t a c t w i t h m i c r o o r g a n i s m s p r e s e n t i n o i l e m u l s i o n s d u r i n g m a n u -

f a c tu r e a s m a y b e t h e s i t u a t i o n w i t h ' d r a w n w a l l i ro n e d ( D W l ) c an s ,

s u b s e q u e n t l a c q u e r i n g a n d s t o v i n g r e s u l t s i n s t e r i l e o r n e a r s t e r i l e

sur faces .

C o n s e q u e n t l y t h e le v el o f c o n t a m i n a t i o n o n c a n s a t t h e t im e o f us e

r ef le c ts p o s t - p r o d u c t i o n h a n d l i n g a n d s to r ag e .

T r a n s p o r t o f u n p r o t e c t e d c a n s i n o p e n l o rr ie s m a y r e s u l t i n h e a v y

c o n t a m i n a t i o n e s p e c i a ll y o n t h e o u t e rm o s t , m o r e e x p o s e d c a n s . S i m i l a r

p i c k -u p o f m i c r o o r g a n i s m s m a y o c c u r i n w a r e h o u s e s n e c e s s it a ti n g

c l e a n i n g b ef o r e u se . U n p a s t e u r i s e d c a n n e d b e v e r a g e s m a y r el y o n a

p r e s e r v a t i v e s y s t e m w i t h v e r y l o w p r o d u c t c o n t a m i n a t i o n , f i l l e d u n d e r

' c l e a n ' c o n d i t i o n s . H e r e w a s h i n g c a n s b e f o r e f i l l i n g i s e s s e n t i a l ( T a b l e 1).

P r o d u c t s w h i c h a r e f il le d c o l d , a n d w h i c h d e m a n d a l o w le v el o f i n i ti a l

c o n t a m i n a t i o n o f c a n s i f s p o i l a g e i s t o b e a v o i d e d , i n c l u d e s w e e t e n e d

T A B L E 1

M e a n C o u n t / C a n a n d A s s u m e d % R e d u c t i o n A f t er H o t W a t e r (9 0 C ) W a s h i n g o n a

2 5 - C a n S a m p l e

Medium Count Unwashed Washed 96 reduction

N u t r i e n t a g a r T o t a l 5 1 .2 3 .2 3 9 3 .7

M a l t a g a r T o t a l 2 4 -6 3 -8 5 8 4 .4

M a l t a g a r Y e a s t > 1 I - 4 0 . 1 5 9 9 .3

M a l t a g a r M o u l d s 8 .9 3 -0 7 6 5 .5

M a l t a g a r O t h e r s < 4 - 3 0 -6 1 8 5 .8

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ygiene aspects o f packaging in the food industry

389

c o n d e n s e d m i l k, m a r g a r i n e a n d b u tt er . H e a v y c o n t a m i n a t i o n o f

c o n t a i n e r s , e s p e c i a l l y w i t h f u n g a l s p o r e s, c a n g i v e r is e t o b u t t o n m o u l d s i n

s w e e te n e d c o n d e n s e d m i l k a n d b l a c k s p o ts o n m a r g a r i n e a n d b u t te r.

U n d e s i r a b l e c h a n g e s h a v e b e e n r e co r d e d f or c a n n e d m a r g a r i n e w h e r e

i n f e c t i o n i s t h o u g h t t o h a v e o c c u r r e d v i a d u s t ( D a l l y n E v e r t o n , 19 72 ).

T o a v o i d s u c h p r o b l e m s s p e c i a l p r o te c t i o n o f c o n t a i n e r s m a y b e

n e c e s s a r y d u r i n g t r a n s p o r t a t i o n a n d s to r ag e , fo l lo w e d b y t r e a t m e n t w i th

h o t a i r o r f l a m i n g p r i o r t o f i l l i n g .

P A P E R A N D B O A R D

P a p e r a n d b o a r d a r e w i d e ly u s e d p a c k a g i n g m a t e ri a ls w h o s e m i cr o -

b i o l o g i c a l q u a l i t y i s g r e a t l y i n f l u e n c e d b y t h e r a w m a t e r i a l s a n d t h e

s u b s e q u e n t c o n t ro l o f c o n t a m i n a t i o n d u r i n g m a n u f a c t u r i n g p r o ce ss es .

C a r e f u l a t t e n t i o n t o t h e v a r i o u s f a c t o r s i n v o l v e d m a y s e r v e t o r e d u c e

c o n t a m i n a t i o n w i t h o u t c o m p l e te l y e l i m i n a t i n g it. S m a l l n u m b e r s o f

m i c r o o r g a n i s m s a r e l i k e l y t o b e p r e s e n t i n t h e f i n a l p r o d u c t. A n t i m i c r o b i a l

a g e n t s a re n o r m a l l y u s e d t o p r o v i d e t h e a d d e d p r o t e c ti o n n e e d e d ( W e i r ,

1 9 8 2 ) . H o w e v e r t h e u s e o f a n a n t i m i c r o b i a l a g e n t m a y n o t a l w a y s b e

d e s i r a b l e , o r a c c e p t a b l e , e s p e c i a l l y w h e r e f o o d i s t o b e p a c k a g e d . I n t h i s

c a s e s o m e f o rm o f s u r f a c e c o a t i n g i s n e c e s s a r y w h i c h c a n b e w a x , f oi l o r a

p o l y m e r . W a x f i l m s c a n b e s u s c e p t i b l e t o m i c r o b i a l a t t a c k a t t h e w a x -

f ib r e in t e r fa c e u n d e r c o n d i t i o n s o f h i g h r e la t iv e h u m i d i t y (R H ) , h o w e v e r

w a x c o a t e d m a t e r i a l s a r e s ti ll w i d e l y u s e d . S t a n d a r d s f o r b o a r d

c o n t a i n e r s a r e v a r i e d b u t y o n B o c k l e m a n n ( 1 9 7 5 ) r e g a r d e d l 0

o r g a n is m s / 1 0 0 c m 2 a s v e r y c le a n , a n d t h e U S D e p a r t m e n t o f H e a l t h

E d u c a t i o n a n d W e l f a re (1 96 6) g iv e a s t a n d a r d o f n o t m o r e t h a n l

o r g a n i s m / c m 2 a s a c c e p t a b l e , w i t h n o t m o r e t h a n 2 50 /g o f p a p e r.

B o a r d a n d p a p e r p a c k a g i n g m a t e r i a l s n e e d a d e q u a t e p r o t e c t i o n

d u r i n g t r a n s p o r t a t i o n a n d s u b s e q u e n t s t o ra g e n e e d s c a r e fu l R H c o n t ro l .

S o m e g u i d e l i n e s a r e p r o v i d e d i n t h e U S D e p a r t m e n t o f H e a l t h

E d u c a t i o n a n d W e l f a r e p u b l i c a t i o n ( 1 9 6 6 ) .

P L A S T I C P A C K I N G M A T E R I A L S

A t t h e ti m e o f m a n u f a c t u r e p a c k a g i n g p r o d u c ts m a d e f ro m p o l y m e r s a r e

n e a r st er il e. T h e h i g h t e m p e r a t u r e s n e e d e d f o r m o u l d i n g o r e x t r u s i o n a r e

s u f f i c i e n t t o d e s t r o y a n y m i c r o o r g a n i s m s p r e s e n t o n t h e g r a n u l e s .

C o n t a m i n a t i o n o n f i n is h e d p r o d u c ts r e p re s e nt s s u b s e q u e n t p i c k- u p.

W i t h g o o d c o n t r o l t h e c o n t a m i n a t i o n l ev e l c a n b e o f t h e s a m e o r d e r a s

t h o s e q u o t e d f o r p a p e r a n d b o a r d a b o v e ( T a b l e 2 ) .

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390 H. Dal l yn . D. Sho r ten

TABLE 2

Number of Microorganisms Isolated From Plastic Containers and Lids Over a 6 Year

Period

S a m p l e s iz e M e a n c o u n t~ u n it M e a n c o u n t / lO 0 c m 2

Containers 6025 1 89 0 78

Lids 4124 bOO 1 22

Conta mina tion from dust may occur because of inadequate cleaning

(Table 3).

Compressed air is frequently used to move containers. Air contains

moisture which condenses as water droplets on compression. In the

piped compressed air supply for pot conveyor systems the water collects

and drains out through valves fitted at the lowest points in the pipe work.

The valves may be automatic or manua lly operated but if water is

allowed to accumulate it has been found to contain as many as 3 106

bacteria/ml, with a possible threat of contamination to the air supply.

In containers produced by blow-moulding techniques the air supply

used can constitute a major source ofcontamination. The system must be

designed to provide dry air free from dust, oil and microorganisms.

TABLE 3

Effect of Cleandown Procedures on Numbers of

Microorganisms Recovered From Containers

L i n e C o u n t ~ C o n t a i n e ra

B e f ore ch and ow n A f t e r ch ando w n

A 42 2 0 20

B 48 1 80

C 29 9 0 60

UMean of 10

Manual handlin g always carries a risk of contamination. This can be

made worse by practices such as the use of water-based adhesive

gummed tape for sealing cartons, In one instance organisms were being

transferred in excessive numbers to formed pots via the operator s hands.

Improved pot handling, automatic carton-sealing equip ment and self

adhesive tape removed the hazard.

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ygiene aspects o f packaging in the food industry 391

h e v a l u e o f e d u c a t i o n

T h e i m p l e m e n t a t i o n o f a n y s y s te m o f p r o d u c t i o n h y g i e n e in v o lv e s

c o - o p e r a t i o n b e t w e e n t h e m i c r o b i o l o g i s t s , f a c t o r y m a n a g e m e n t a n d

w o r k e rs . A w a r e n e s s o f t h e h y g i e n e n e e d s c a n b e e x p l a i n e d u s i n g w el l

d e s ig n e d d e m o n s t r a t i o n s a n d t ra i n in g .

e s t i n g o f c o n t a i n e r s

R o u t in e m i c r o b i o l o g i c a l c h e c k s o f m a n u f a c t u r e d c o n t a i n e r s a n d l id s

h e l p t o e n s u r e t h a t t h e s e a r e b e i n g m a n u f a c t u r e d t o m e e t a d e q u a t e

m i c r o b i o l o g i c a l s t a n d a r d s T a b l e 2).

G L A S S C O N T A I N E R S

Glass bo t tl e s, becau se o f t he h igh t empe ra tu re s used i n t he i r man ufac tu re ,

a r e s te ri le . G e n e r a l l y t h e a t m o s p h e r e s u r r o u n d i n g b o t tl e s d u r i n g c o o l i n g

is s o m e w h a t h o s t il e to m i c r o o r g a n i s m s M o o d y , 1 97 7). C o n s e q u e n t l y ,

p ro v id in g some fo rm o f p ro t e c t i on is g iven a t th i s s tage , s t e ri le bo t tl e s o r

bo t t le s w i th a ve ry low m ic rob i a l l oad a r e p roduced . I f g l a ss con t a ine r s

a r e su i t ab ly p ro t ec t ed a t a l l st ages f rom the t ime t hey a r e m ade t o the t ime

w h e n t h e y ar e f i l le d m i c r o b i o l o g i c a l p r o b l e m s w i ll b e a t a m i n i m u m ,

t h e r e b y b e n e f i t t in g t h e p a c k a g i n g o f b ev e ra g e s b e e r a n d w i n e ) a n d

p h a r m a c e u t i c a l s .

Th e i n t eg r it y o f t he c ap o r c l osu re i s v i t a l i f t he co n t en t s a r e t o be

p r o t e c te d f ro m t h e i n g re s s o f m i c r o o r g a n i s m s . T h e d e s i g n o f b o t h b o t tl e

a n d c a p m u s t g i v e a d e q u a t e p r o t e c t i o n t o t h e p r o d u c t a n d w i l l b e a n

im po r t an t f ea tu re where s t e r il it y is r equ i red : t h i s i s d i s cus sed i n r e l a t i on

to p h a r m a c e u t i c a l p r o d u c t s b y A l l w o o d 1 98 2) a n d f o r f o o d b y H e r s o m

a n d H u l l a n d 1 98 0).

C A P S

Plas t i c caps w i l l be sub j ec t t o s imi l a r cons ide ra t i ons t o t hose which

a p p l y t o p l a s t i c c o n t a i n e r s . M e t a l c a p s w i l l d e p e n d o n w h e t h e r t h e s e

h a v e c o a t e d c a r d b o a r d i n s e rt s o r o t h e r w a d m a t e r ia l ) o r w h e t h e r a

s e a l i n g c o m p o u n d h a s b e e n a p p l i e d d i r ec t ly t o th e c a p . B o a r d i n s e r ts w il l

b e s i m i l a r i n m i c r o b i o l o g i c a l p r o p e r t ie s to o t h e r p a p e r a n d b o a r d

p a c k a g i n g .

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392 H. D ally . D. Shorten

M o u l d s o n c a p s m a y b e a p a r t i c u l a r p r o b l e m , f ir st i n r e l a ti o n to th e

p r o d u c t i n t h e c o n t a i n e r c l o s e d b y th e c a p , a n d s e c o n d l y w h e r e t h e l in i n g

c o m p o u n d o f t he c ap s u p p o rt s m o u l d g r o w th . T h e l a t t e r m a y o n l y

b e c o m e a p r o b l e m i n t h e t ro p ic s w h e r e a c o m b i n a t i o n o f h i g h h u m i d i t y

a n d t e m p e r a t u r e f o r e x t e n d e d p e r i o d s a l l o w s s po r es t o g r o w a n d s p r e a d

to o t h e r c ap s . T h e p r o b l e m m u s t b e o v e r c o m e b y a c o m b i n a t i o n o f g o o d

f a c to r y h y g i e n e , s to r a g e a n d t h e s e l e c t io n o f m a t e r ia l s w h i c h w i l l n o t

s u p p o r t m o u l d g r o w th .

R E F E R E N C E S

AU wood, M . C. (1982). M edica l app l ica t ion s o f the rm al p rocesses . I n : Principles

a n d P ractice o f Disinfection Preservation an d Sterilisation. ed. A. D. Ru sse l l ,

W . B. H ug o G. A. J . Ay cl i ffe , Blac kw ell Scien t i f ic , O xfo rd, pp. 469-77.

Da l lyn , H. Eve r ton , J . R . (1973) . Th e Inf luence of pack aging ma te r i a l s on

mic rob ia l g rowth . Food Technology in Australia 25, 436--45.

He rsom , A. C . H ul l an d , E . D. (1980) . Can ned Foods. Thermal Processing an d

Microbiology 7 th E dn . C hu r c h i l l L i v ings t one, L on don .

Ingra in , M. S im ons en , B . (1980) . M ea t s an d m ea t p roduc t s . In : Microbial

Ecology o f Foods Vol I I . ICMSF, Academic Pre ss , London , pp . 391-2 .

M oo dy , B. E. (1977). Packaging in G lass 2 n d E d n . H u t c h in s o n , B e n h a m , L o n d o n .

Sinel l , H. J . (1980). Packaging. In: Microbial Ecology of Foods Vol I . ICMSF,

Academic Pre ss , London , pp . 193-204 .

U S D e pa r t m e n t o f H e a l th , E duc a t i on a nd W e l fa r e (1966). Fabrication o f Single

Service Containers a nd CIosur s for M ilk an d M ilk Pro duc ts- guide for

Sanitation Stamlards F D A , W a s h i n g t o n D C .

yon B o c k l e m a nn , I. (1975 ). M i k r ob i o log i s c he E i ge ns c ha f t e n yon V e r pa c k -

ungsma te r i a l f a r Lebensmi t t e l . Al imenta 14, 145-9.

W ei r, B . (1982) . P re se rva t ion o f pape r a nd pu lp . In : Principh an d Practice o f

Disinfection Preservation an d sterilisation ed. A. D. R usse l l , W. B. Hu go

G. A. J . Ayliffe , Blackwell Scient i f ic , Oxford, pp. 358-64.