Environment Canada

Environnement Canada

Fisheries

Service des caches

and. Marine Berytte

erdes sciences de la mer

Canada. Fisheries and Marine Service. Inspection Branch. TECHNICAL REPORT SERIES

09039397

Protective Qualities of Four Diffe ent Packaging Materials For ishery Products

by AS. Dewar, E.B. . Guptilit F.H. Alleri and RI.. Selfridge

Tectsnical Report Series No. MAR/T-75-3 Inspection Branch Maritimes Region

c't.3),(e

Protective Qualities of Four Different Packaging Materials for Fishery Products

By

A.B. Dewar, E.B. Guptill, F.H. Allen and R.L. Selfridge

Technical Report Series No.Mar/T-75-3 Inspection Branch Maritimes Region

Abstract

Lobster meat (Homarus americanus) and herring fillets (Clupea harengus) were packed and stored in four packaging materials, namely; 1/2 lb. flat (307 x 200.25) tin plate can (tin can), aluminum foil laminate pouch (construction from outside to inside: white lacquer/0.012 mm polyester/adhesive/0.007 mm aluminum foil/adhesive/0.07 mm modified high density polyethylene), poly bag (3.00 mils polyethylene/adhesive/1.00 mil nylon) and waxed cardboard carton, to determine the protection provided by these packaging materials. Lobster meat selected as a low fat (ay. 1.5%) fishery product, was packaged, frozen and stored at -18°F for 24 months in the packaging materials mentioned above. In addition, lobster meat was heat processed in the 1/2 lb. flat tin can and the aluminum foil laminate pouch and stored at room temperature for 24 months. Herring fillets, selected as a high fat (ay. 16%) fishery product, were also packaged in the four materials used in this study, and stored at -18°F for 24 months. Taste panel and organoleptic examinations were carried out on samples from the 10 groups at 0, 6, 12, 18 and 24 months storage. Results show that heat processed lobster meat packed in the tin can and the aluminum foil laminate pouch, had a storage life of 18 months. Frozen lobster meat in the tin can had a storage life of over 24 months, 23 months in the aluminum foil laminate pouch, 18 months in the poly bag and 5 months in the waxed cardboard carton. Frozen herring fillets had a storage life of over 24 months in the tin can, 23 months in the aluminum foil laminate pouch, 19 months in the poly bag and 8 months in the waxed cardboard carton.

-2 -

Introduction Over the years, many changes have come about in the field of food packaging. The changes were particularly rapid in the last few years. As pointed out by Norman and Rees (1972) development for many years was concentrated on improvements of the manufacturing process, handling techniques in the cannery and in the modifications of materials to maintain its cost at a reasonable level. Today, consumers demand more convenient, more aesthetic packaging. This produced imaginative development in the field of food packaging. In recent years, flexible material was introduced for the packaging and protection of foods. Refrigerated or frozen foods, dehydrated, high-sugar and high acid-content products were the first to be protected by this material. While flexible packaging has its advantages and disadvantages, there is still a definite need for a flexible packaging material or flex can that would be suitable for the containment of heat preserved products. Davis et al (1972) defines this type of container as a biologically commercial sterile food container in which the food product, after being sealed in, is sterilized at temperatures in excess of 212°F (generally, the process temperature is between 230-250°F). Most foods with a pH above 4.5, require this type of process.

3

Davis et al (1972) list some of the advantages of the flexible container or retort pouch as follows: 1. Improved product quality, flavour, colour and texture due to shorter process time. 2. The product does not require refrigeration. 3. The container is light in weight, compact (more food, less liquid), and requires less storage space than a can. 4. A wider selection of portion packs can be offered since it is relatively easy to change package size. 5. Less cooking time required - food can be heated to serving temperature in 3-5 minutes. 6. The container is easy to open. 7. It is easy to dispose of. However, it must be pointed out that the retort pouch has some disadvantages too. Filling and sealing procedures require special attention. Contamination of seal surfaces with water or fat seriously reduce the seal strength. During heat processing, superimposed air is required to reduce the strain on the seams, since seal strength is reduced considerably at processing temperatures in the range of 230-250°F. The retort pouch must be vacuum packed to remove headspace gas prior to closure, so that the internal pouch pressure developed during retorting will be kept to a minimum. Otherwise, the seals have a tendency to rupture even if superimposed air pressure is applied during retorting.

4

Adequate and uniform water circulation throughout the load must be provided at all times. Handling and even packing of flexible packages also require special consideration. Generally, the protection provided by flexible containers depends upon the durability of the packaging material (e.g. its tensile strength and its ability to withstand initial tear and scratching and to withstand heavy impack and prolonged flexing); its chemical resistance and its gas barrier properties. The product and package must be compatible. Changes in the product caused by a packaging material may render it unacceptable. Odours or flavours in food caused by migration of plasticizers from plastic films or by unevaporated solvents from inks or coating may taint the product. Some of the foil laminates are claimed to have good barrier properties which approaches that of metal cans. To estimate the protective qualities of laminates, two laminates were compared to the tin plate can used to package fishery products. An aluminum foil laminate (whose construction from the outside to the inside is as follows:) white lacquer/0.012 mm polyester/adhesive/0.007 mm aluminum foil/adhesive/0.07 mm modified high density polyethylene) and a poly bag identified as follows: 3.00 mils polyethylene/adhesive/1.00 mil nylon - total gauge 4.25 mils - adhesive is polyurethane type - polyethylene is in low density range,

5

were employed for the packaging of lobster meat and herring fillets. Lobster meat, with an average fat content of 1.5%, was chosen to represent a low fat fishery product, while herring fillets, with an average fat content of 16%, was chosen to represent a relatively high fat fishery product. The tin plate can was used as the control packaging material. The regular waxed cardboard carton (1 lb.) was also used for comparison purposes.

Materials and Methods Live lobster, weighing less than one pound each, were employed in this study. The lobsters were cooked in fresh water for 12 minutes at 212°F after which they were cooled with cold, fresh running water. The meat was extracted from the shells by hand and was washed in cold, fresh running water, drained and packaged using the materials indicated below: Type of Container

No. of Samples

Fill-in Weight

Treatment

Sealing

1/2 lb. flat tin can (307 x 200.25)

50

6.5 oz

30 ml 8% NaCl

Vacuum 21 in Hg

Aluminum foil laminate

50

6.5 oz

30 ml 8% NaCl

Vacuum 30 in Hg

Poly bag (laminate)

25

6.5 oz

30 ml 8% NaCl

Vacuum 30 in Hg

Waxed cardboard carton

25

6.5 oz

30 ml 8% NaCl

No Vacuum

- 6-

The tin cans (tin plate) were vacuum sealed (vacuum 21 in. Hg) in a semi-automatic vacuum sealing machine and the two laminates were sealed with an ACDL vacuum packaging machine (Vacuum 30 in. Hg). Twenty-five (25) samples from each group were frozen in a plate freezer, immediately after packing and then stored at -18°F until examination. The remaining 25 samples (tin cans) and 25 samples (aluminum foil laminate) were heat processed and then held at room temperature (70°F) until examination. The cans were heat-processed for 35 min. at 240°F, then cooled in the retort by means of water and air pressure (12 psi) until the average temperature of the can contents was approximately 100°F. The retort-pouches were heat processed under water (held in position by wire mesh racks) for 30 min. at 240°F. A superimposed air pressure of 20.3 psi was maintained (10.3 due to the water-steam temperature and 10 lb. overriding air pressure). Adequate water circulation in the retort was maintained by "bubbling-in" a continuous flow of air. The containers were water cooled in the retort using superimposed air pressure until the average temperature of the flexible container reached room temperature. The canned lobster received an F value of 4.0 during pro0 cessing. The heat process for the retort-pouch was calculated to be an F value of 4.1. 0

-7-

Herring used in this study was caught in gill nets off Three Fathom Harbour, N.S. After landing at dockside, the fish were immediately placed in styrofoam boxes, iced and transported to the Halifax Fish Inspection Laboratory. The average fat content of the herring flesh was 16%. Prior to packing, the herring were filleted, the fillets washed in cold running fresh water, drained, then packaged as indicated below.

No. of Samples

Fill-in Weight

Sealing

1 lb. flat tin can (404 x 206)

25

15 oz

Vacuum 21 in Hg

Aluminum foil laminate

25

16 oz

Vacuum 30 in Hg

Poly bag (Laminate)

25

16 oz

Vacuum 30 in Hg

Waxed cardboard carton

25

12 oz

No Vacuum

Type of Container

The herring samples were sealed, frozen and stored in the same manner as the frozen lobster meat samples. All the containers were frozen and held at -18°F. Organoleptic examinations were carried out by a trained taste panel on coded samples after 0, 6, 12, 18 and 24 months storage. A sample consisted of 5 randomly selected containers.

- 8

The quality of the samples was rated on a 10-0 point scale. A score of 10 corresponded to normal or the most desirable, and a score of 0 for the least favourable rating. A score of less than 5 indicates reject quality. The overall quality of a sample was expressed by the lowest score assigned to either appearance, odour, flavour or texture. The final score of an assessed characteristic was obtained by averaging the individual scores of the 5 sample units examined at any given sampling time.

Results and Discussion Heat Processed Lobster Meat Figure 1 illustrates the storage life obtained in, the tin can and the aluminum foil laminate container, at room temperature. The overall quality of the lobster meat in the retort-pouch was rated slightly lower than the product in the tin can. The pigment'of the lobster meat had a tendency to adhere to the foil much more than to the surface of the metal can. This harms the appearance of the product. The meat in the pouch pack had slightly more greyish discolouration than in the can pack. The normal red colour of the claw tips in the tin can had slightly more greenish discolouration than in the pouch pack at the end of the storage period. However, in spite of this, the overall quality of the lobster meat in the cans was still assessed better than in the pouches. Odours and flavours were rated lower for the pouch pack at the end of the 2 year storage period. The drained weight and the pH of the heat processed meat did not Change significantly during 2 years of storage at ad:dant temperature.

9

Frozen Lobster Meat Figure 2 illustrates the protection provided by the 4 packaging materials to samples at -18°F storage. The tin can gave the.best protection followed by the aluminum foil laminate pouch, the poly bag and the waxed paper carton. The waxed carton afforded little protection to the lobster meat. The claw meat in the waxed carton had a strong dulce like odour and flavour due to oxidation of the fatty part of the claw, (the non straited muscle). Discolouration and freezer burn (dessication) were also evident after 6 months storage. The tail meat was quite tough and the texture of the claws was pulpy and granular-like. The tin can, aluminum foil laminate and poly bag all provided better protection to the samples than the waxed cardboard carton. The storage life of samples packaged in the aluminum foil laminate was slightly shorter than the storage life of samples in the metal cans.

Comparison of Heat Processed and Frozen Lobster Meat Figure 3 shows the taste panel assessment of heat processed and frozen lobster meat packed in the various types of containers at the end of 24 months storage. The tin can (A and C) gave the best protection, both for the heat processed and for the frozen pack. It was closely followed by the aluminum foil laminate pouch (B and D). The poly bag provided fairly good protection for the frozen samples.

Frozen Herring Fillets Figure 4 shows the protection provided by the 4 packaging materials for the frozen herring fillets over a 24 month period. As in the case of

- 10 lobster (see figure 2), the relative protective properties of the packaging materials were similar. The tin can provided the best protection to herring fillets, followed by the aluminum foil laminate, then the poly bag and the waxed cardboard carton. The low taste panel scored for the waxed carton points out the lack of protection from oxidation and dessication resulting in rancidity, discolouration and adverse texture ratings. The apparent improvement in quality at 18 months storage in the aluminum foil laminate pouch and the waxed paper carton is considered attributable to variations in taste panel response and the quality of the raw material.

Storage Life of Heat Processed and Frozen Samples in the Various Packaging Materials Figure 5 shows the storage life of samples in the various packaging materials under two different storage conditions. Frozen lobster meat in the metal can had a storage life of more than 24 months at -18°F. The storage life in aluminum foil laminate under the same conditions was 23 months, and in the poly bag, 18 months. Lobster meat remained of acceptable quality for only 5 months in the waxed paper carton. Heat processed lobster meat was of acceptable quality for approximately 18 months in the tin can and also in the aluminum foil laminate pouch. Herring fillets had a storage life of over 24 months in the tin can, 23 months in the aluminum foil laminate pouch, 19 months in the poly bag and 8 months in the waxed cardboard carton at -18°F. Neither the aluminum foil laminate nor the poly bag imparted odours or flavours to the product.

The aluminum foil laminate showed no adverse affects of heat processing at 240°F. This material did not deteriorate during storage, i.e., it didn't peel or separate, and no pin holes were detected even at the end of 24 months storage at room temperature or at -18°F. Neither delamination nor cracking was observed in the poly bags after 2 years storage at -18°F.

Conclusion The tin plate can provided the best protection in both the heat processed and in the frozen products studied. Pouches made from aluminum foil laminate approached the tin can in their protection properties. Although the poly bag gave less protection than the metal can or the aluminum foil laminate, it has the added advantage of being transparent. Waxed cardboard cartons without a cellophane insert or waxed ovenwrap give poor protection to the product. The aluminum foil laminate pack resisted adverse retorting effects well, but requires special care in sealing, retorting and handling to ensure the integrity of the seal as well as the container.

Acknowledgements The authors are indebted to the following persons for their contribution to this work: S. Varga, W.E. Anderson, G.G. Sims, M.C. Murray, B. Lauer, J.B. Myrick, J. Wang and G.E. Mack for participation in taste panels. The authors are especially indebted to Aldan of Canada Limited °for providing the aluminum foil laminate for this study, and to Du Pont of Canada Limited for providing the poly bags.

- 12 -

References

Alder - Nissen, J. 1972. Fully Preserved Goods in Flexible Packages. Emballage 2, p 12. Davis, R.B., F.E. Long, and W.F. Robertson. 1972. Engineering Considerations in Retort Processing of Flexible Packages. Food Technology, 26, No. 8, p 65-68. Konigsbacher, K.S. 1974. Technology for Shelf Stable Foods. (First of two parts) Food Product Development, 8, No. 7, p 18-25. Konigsbacher, K.S. 1974. Technology for Shelf Stable Foods. (Second of two parts) Food Product Development, 8, p 28-30. Norman, G.F. and J.A.G. Rees. 1972. New Era for Metal Containers. Food Manufacture, 47, No. 9, p 27-31. Sacharow, S. 1972. "Testing Packaging Films". Food Product Development 6, No. 4, p 40-42. Turtle, B.I. and M.G. Alderson. 1971. Sterilisable Flexible Packaging. Food Manufacture, 46, No. 9, p 23-37.

Fig 1: The quality of heat processed lobster meat packed in tin plate cans and aluminum foil laminate.

10-

A B Legend: A-Tin plate can B -Aluminum foil laminate pouch

2

4

6

8

10

Storage time (months)

12

14

16

18

20

22

24

Fig 2: The quality of frozen lobster meat packed in four different packaging materials during storage at -18°F.

10-

Legend: A-Tin plate can 2-

B - Aluminum Laminate Pouch C -Pay Bag

1-

D -Waxed Cardboard Carton

0 2

4

6

8

10

12

14

16

18

Storage Time (months)

20

22

24

Fig 3: The quality of heat processed and frozen lobster meat packed in different packaging materials at the end of 24 months storage.

109— 8—

Overall Quality Score

7 6— 5 4— 3— A

2

B

C

D

E

1— 0 Heat processed

Frozen (-18°F)

Legend: A - Tin plate can B - Aluminum foil laminate C - Tin plate can D - Aluminum foil laminate E - Poly bag F - Waxed cardboard carton

F

Fig 4: The quality of frozen herring fillets packed in four different packaging materials during storage at -18°F.

Overall Quality Score

10

Legend: A - Tin plate can - Aluminum foil laminate pouch C - Poly bag D - Waxed cardboard carton

0

2

4

6

8

10

12

14

16

Storage Time (months)

18

20

22

24

Fig 5 LOBSTER MEAT Storage life in months

24-

Legend: A - Tin plate can (Frozen) B - Aluminum foil laminate (Frozen) C - Poly bag (Frozen) D - Waxed Cardboard Carton (Frozen) E - Tin plate can (Heat processed)

0(

A

B

C

E

D

F

Jl

F - Aluminum foil laminate (Heat processed)

Frozen (-18°F) Heat processed

FROZEN HERRING FILLETS Storage life in months 241)

Legend: 18-

v

A - Tin plate can B - Aluminum foil laminate C- Poly bag D - Waxed Cardboard Carton