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Seafood safety & quality
What are seafood safety and quality?
Why are safety and quality important?
Food safety regulations
Hygiene
Cleaning and sanitising practices
Personal hygiene practices
Sound seafood handling practices
Determining the quality of seafood
All seafood
Finfish
Prawns
Crustaceans (excluding prawns)
Mussels, oysters and other bivalves
Scallops
Squids, cuttlefishes and octopuses
Dried seafood such as beche-de-mer
Sea urchin
Frozen seafood
Smoked seafood
Canned, bottled (including pickled) and tubbed seafood |
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What are seafood safety and quality?
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Australian consumers demand and deserve seafood that is both safe to consume and of a high quality.
Safety relates to the assurance that a seafood will not cause harm (as a result of biological, physical or chemical hazards) to the consumer when it is stored, prepared and/or eaten according to its intended use. Safety is a particularly important issue when seafoods are to be eaten raw as cooking destroys many potentially harmful contaminants.
Quality refers to the positive attributes of a seafood that are required or stated as being necessary by an industry or client standard. Seafood quality can be assessed by its appearance, odour, texture and taste.
The concepts of safety and quality differ. Safety dictates the non-negotiable characteristics that must be present for a product to be fit for human consumption whereas quality defines other characteristics that determine what a product is fit for. For example, two rocklobsters may be equally safe to eat, but if one has damaged legs it will be considered of lesser quality than a complete rocklobster when required for display. Furthermore, quality can be subjective: seafood considered acceptable by one consumer might be unacceptable to another. Generally, the more positive attributes a product has or the less variation there is in a particular pack or line of product, the higher the perceived level of quality, and vice versa.
To keep seafood safe and to maintain quality it is necessary to identify and control safety hazards and quality spoilers. This is the shared responsibility of the industry, governments and the seafood-eating public. Primary and secondary hazards and spoilers are listed in the two tables below.
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Primary seafood safety hazards and quality spoilers
| Hazard |
Cause of the contamination |
Problems |
Biological
(safety hazards and quality spoilers) |
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| Micro-organisms |
Food poisoning bacteria, food spoilage bacteria, viruses, mould and fungi
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Seafood is not fit to sell or eat. Possible food poisoning if eaten (e.g. serious health problems such as Staphylococcus infection can occur when seafood is par-cooked and then re-cooked later) and/or food spoilage (flesh texture soft and mushy, strong, unpleasant “fishy” smell and taste) |
| Enzymes |
Inappropriate handling, processing or preparation |
Discoloured flesh, black spot, belly burn and belly burst. Quality may be reduced but flesh can usually still be eaten after trimming. The flesh of some shellfish (e.g. crabs) may become mushy. |
Biotoxins
(e.g. ciguatera, histamine, etc.)
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Present in environment where caught or, in the case of histamine, poor handling
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Most biotoxins can cause serious food-borne illness even though the seafood looks, feels, smells and tastes good. Contamination of this kind is at present undetectable, but field kits are under development for ciguatera. Know where your seafood is caught and be aware of contaminated areas. |
Physical
(safety hazards and quality spoilers) |
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| Foreign matter |
Contaminants such as sand, mud, dirt, dust, hairs, feathers, animal droppings, pen lids, paper clips, staples, bolts, nuts, string, cardboard, insects, etc. |
Contaminants of this kind can lead to product wastage or to consumer injury or illness. If it is impossible to remove foreign matter by washing, wiping or processing, the seafood becomes unfit for sale and unfit to eat. In some cases, it will be unfit for sale even if the foreign matter is removed. |
| Physical damage |
Inappropriate handling or poor packaging |
Chemical
(safety hazards and quality spoilers) |
Inappropriate cleaning programs and/or product source can lead to contamination by detergents, sanitisers, heavy metals such as mercury, pesticides and organochlorin-type chemicals, grease, etc. Some chemicals are intentionally added to seafood in controlled doses (e.g. metabisulphite to prawns and other food additives). |
Contaminants of this kind can lead to product wastage or to consumer injury or illness. If amounts in the flesh are in excess of the Food Standards Code, the seafood must be considered unfit for sale and unfit to eat. |
Secondary seafood safety hazards and quality spoilers
| Spoiler |
Conditions that allow spoiling |
Problems/damage |
Prevention |
Oxidation
(quality spoiler)
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• Poor handling—seafood flesh exposed to the air; poor packing or inadequate glazing
• Incorrect holding temperature
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• Oxygen breaks down the unsaturated fats (oils) of the seafood, causing discolouration of exposed flesh and rancidity.
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• Keep seafood well covered or packaged. Make sure frozen seafood is properly glazed (i.e. with a full protective coat of ice).
• Keep frozen seafood at or below –18°C.
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Dehydration
(quality spoiler)—
also called “freezer burn” when severe and can affect both chilled and frozen seafood |
• Poor handling—seafood flesh exposed to the air
• Poor packing and/or packaging |
• Loss in product weight and loss of fluids
• Increase in oxidation rate, and deterioration of texture and appearance
• Irreversible damage to texture (wrinkled flesh)
• Lightening of colour
• Loss of flavour |
• Package, store and display fresh, wet or frozen seafood carefully and appropriately—keep it moist (or well covered if frozen) and moving.
• Store frozen seafood at –18°C or below. |
Rough handling
(quality spoiler)—
physical damage |
• Rough capture method
• Rough storage and handling methods, such as overfilling containers, picking up large fish by the tail or throwing seafood
• Poor packaging
• Uncaring, untrained careless or rushed staff |
• Breaking of appendages such as legs, bruising, rupturing of blood vessels
• Squashing, squeezing
• Blood-spotted fillet
• In extreme cases, strong “fishy” smells and unpleasant tastes |
• Ensure that seafood is always handled with due care and attention.
• Do not handle semi-thawed seafood.
• Keep seafood moving. |
Parasites
(safety hazards and quality spoilers) |
Contamination
• Physical damage on removal
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• Unwanted worms and bugs, etc. that invade the flesh
• Damage caused to the flesh when trying to remove parasites (excessive trimming)
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• Fillets can be checked by candling (where seafood is held up to a strong light; parasites appear as darker areas within the flesh).
• Parasites can be killed by cooking and freezing. |
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Why are safety and quality important?
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Thousands of Australian consumers contract food-borne illnesses every day, a situation that costs the community millions of dollars each year. Through the implementation of food safety systems in all production stages, the risk of contracting such illnesses can be reduced. Furthermore, any seafood safety incident, such as food poisoning or product contamination, can have a devastating impact on all sectors of the seafood industry, possibly threatening the commercial viability of certain operations.
Consumers today can afford to be very demanding when it comes to food quality. If the quality of one food does not meet their standards, they will select an alternative or not purchase at all. Higher quality is an important source of competitive advantage in the food industry.
To protect and promote the industry, the seafood served to consumers must be both safe and of the highest possible quality.
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Food safety regulations
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Australian laws regulating food safety and hygiene, of which seafood safety is a part, are under the jurisdiction of state, territory and local government health authorities. These laws are intended to ensure that rigorous safety measures are applied throughout the supply chain, and, if you are in any sector of the seafood industry, they apply to you. They have been designed to make the production of safe, clean food easier. Food standards are under the jurisdiction of The Australia New Zealand Food Authority (ANZFA) who publish relevant information in the national Food Standards Code. For more information contact your local and state government health authorities.
It is desirable that every food business have in place a food safety program. These programs require the use of good manufacturing practices and most use Hazard Analysis Critical Control Point (HACCP) to manage food safety. HACCP:
• identifies and analyses hazards;
• identifies where and how hazards are controlled;
• establishes specifications to control hazards;
• covers supervision and monitoring of controls;
• states how hazards, when not in control, are brought back under control;
• verifies that the food safety program is working and appropriate;
• includes keeping of detailed records and allows for fine tuning.
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Temperature
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Many hazards and spoilers are encouraged by fluctuating temperatures. To allow the temperature of seafood to increase is to invite faster microbial growth and a subsequent loss in safety and quality. The spoilage rate is a function of the micro-organisms present, the temperature and the time. The most appropriate temperatures for common handling activities are listed in the table below. Fresh seafood is defined as that which has not been below –1°C; frozen seafood is that which has been kept below –1°C continually since its initial freezing.
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Appropriate temperatures for seafood
| Activity |
Product |
Temperature |
| Storing, transporting, receiving and displaying |
Fresh or wet seafood
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–1°C to +4°C. Generally use shaved, snow or flake ice or an ice slurry.
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Frozen seafood
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Initially frozen to a core temperature of –30°C and then stored and/or displayed at –18°C or colder (storing at –25°C is ideal for most seafood but some, such as tuna, must be kept even colder). Seafood should be transported at –18°C or colder and never received warmer than –15°C.
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Live seafood
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Depends on the product (see pp 198–206). Maintaining the right temperature will ensure that the seafood stays alive at the point of sale. |
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When it comes to keeping seafood safe, no product is entirely risk free. However, steps can be taken to minimise the risk of causing illness. “Hygiene” is the term used to describe the science of preserving health, and the associated practices and procedures. This means making sure that there is never any build-up anywhere, at any time, of anything that provides a good home for micro-organisms such as bacteria and viruses. Hygiene involves following:
• cleaning and sanitising practices (pp 175–178);
• personal hygiene practices (pp 179–180);
• sound seafood handling practices (pp 181–182).
These three areas are summarised in the following pages, particularly for those who work “hands on” in the seafood business. Those in management positions however have additional responsibilities.
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Management responsibilities
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Maintaining safety and hygiene standards is a responsibility shared by an entire organisation. People in management however have responsibilities to provide other staff with the leadership, guidance and tools that allow acceptable standards to be met. Specifically, it is important that management:
• keep abreast of current food safety laws (see previous page);
• set up sound hygiene practices and procedures;
• develop a food safety system;
• give staff the required training.
If you manage staff in a seafood business, check the latest seafood safety practices with government health authorities. Seafood Services Australia (see glossary entry) can provide additional assistance.
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Cleaning and sanitising practices
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All surfaces and utensils that come into contact with raw or cooked seafood should be thoroughly cleaned and sanitised frequently and regularly. This includes benches, cutting boards, bins, serving tongs, vehicles and trays.
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Cleaning
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Cleaning removes visible dirt and such items as blood, guts and scales. It can also help reduce the number of micro-organisms on a product contact surface.
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Sanitising
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Sanitising kills micro-organisms such as bacteria on a cleaned surface and so reduces their number to a safe level. Sanitisers are not good cleaners, so an area or surface must be well cleaned before it can be sanitised effectively.
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Why do we clean and sanitise?
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Some of the more important reasons to clean and sanitise your seafood work area are:
• to meet legal requirements for operating a food premises;
• to remove dirt and waste that could contaminate seafood;
• to reduce food spoilage and prevent food poisoning;
• to prevent harbouring of and/or infestation by rodents and insects;
• to improve the safety and shelf life of seafood products by reducing the numbers of harmful micro-organisms;
• to remove odour-causing bacteria and reduce the chances of “off” flavours;
• to lengthen the life of equipment and prevent it from staining and filming;
• to improve the safety and morale of staff.
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How to clean and sanitise
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Design your own cleaning and sanitising schedule for the food preparation area and display it for all staff to see. An example of a complete cleaning and sanitising routine follows. Each step is applied to the floors, walls, benches, sinks, equipment and any other surface with which seafood might come in contact. Use of detergents and sanitisers must match the instructions on the label. Do not purchase detergents or sanitisers that have no label or that are not labelled clearly.
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1. Dry wipe and sweep
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Dry wipe with a scourer and then sweep with a broom.
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2. Warm rinse
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Rinse with warm water. This will soften any organic matter such as blood and fish guts. Hot water is not recommended until the final rinse (step 6) because it causes organic matter to set and become very difficult to remove.
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3. Scrub
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Scrub with a nylon brush using clean warm water and the right detergent (cleaner) to remove dirt and other material. Leave for about 10 minutes.
Detergent loosens and lifts the dirt and other foreign material. The effectiveness of a detergent depends on:
• contact time (the longer the better);
• temperature (the correct temperature must be used—hotter is not always better);
• concentration (according to the manufacturer’s instructions).
Avoid using an agent that combines detergent and sanitiser because the effects of the sanitiser can be destroyed by contact with dirt or other foreign material.
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4. Warm rinse again
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All areas must be well rinsed with clean warm water to ensure that no dirt or other foreign material remains and a detergent film does not form. If you can, rinse by hosing out the entire area using a low-pressure hose.
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5. Apply sanitiser
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Apply the sanitiser and leave it on for the recommended time to allow the chemicals it contains to work. Remember to use a short residual-life chemical like chlorine if the surfaces are to be used shortly afterwards. Do not use phenol sanitisers as they leave a residue that can taint the seafood.
The effective use of sanitisers depends on:
• their concentration (according to the manufacturer’s instructions);
• the contact time (according to the manufacturer’s instructions);
• their surface coverage;
• the number of micro-organisms present on the surface.
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6. Hot rinse
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Rinse with hot water. Use clean, hot water to rinse off sanitised surfaces. A sanitiser should not be left on any surface longer than is recommended on the label. Some sanitisers can be corrosive on metals such as aluminium. Some sanitisers do not require rinsing off.
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7. Flush drain
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Flush the drainage system for several minutes, with high-pressure water. This will help remove dirt and other foreign material that can build-up in the drain and become a food source for odour-causing bacteria.
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8. Dry
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Dry all areas and equipment or ensure that they air dry quickly. This will help control the growth of unwanted micro-organisms. If a bench top needs to be dried quickly, use disposable paper towels, not a tea-towel.
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Do not forget your deep fryer
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Deep fryers must be cleaned thoroughly, like all other equipment. This can be achieved if you:
1. drain all the oil from the tank;
2. fill with a heavy duty alkaline detergent and boil until clean;
3. rinse with hot water;
4. rinse with a solution of cold vinegar to neutralise the alkali;
5. rinse with cold water.
Items such as deep fryers, shelves, rubbish areas and cash registers must be kept clean as you go and thoroughly cleaned at least once a week.
You should direct any questions about the use of detergents and sanitisers to a reputable cleaning chemicals manufacturer.
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When to clean and sanitise
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At the beginning of the day
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Every piece of equipment and surface is sanitised before any food is brought back in contact with them. This will reduce any build-up of bacteria since the premises were last used; the importance of this activity cannot be overstressed.
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At the end of the day
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This is a major clean when every piece of equipment and every surface is both cleaned and sanitised. Left-over scraps are removed from the building or sealed in waste removal bags and stored in an appropriate place.
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As you go
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While working, frequently clean surfaces and utensils to keep them free of seafood scraps. It is very important that you clean these areas before they dry because dried finfish scales and slime are difficult to remove from areas where seafood is processed.
A weekly cleaning and sanitising roster should be developed clearly indicating which tasks need to be done, by whom, when and where. This information should be located where all staff have easy access to it, and should include provision for relevant staff to initial tasks when they have been performed.
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Check whether it has been done right
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1. Look at the working surfaces
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Do they look clean and dry or do they look streaky and feel greasy? If they are streaky and greasy, they have not been cleaned correctly.
Test stainless steel surfaces by rubbing them with a clean white tissue. If the surface is clean, the tissue should not have any discolouration.
To test for grease, run water over the surface. If there is grease on the surface, the pattern of the water flow will break up.
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2. Move equipment
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Move equipment if possible. This will show whether all areas have only been wiped or if they have been properly cleaned and sanitised.
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3. Check under equipment
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Run your finger under a bench to see if areas have been properly cleaned or just wiped.
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4. Use your nose
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If you can smell it, clean it. Seafood storage and preparation areas should not have a strong “fishy” odour. If they do, it is because they have not been properly cleaned and could therefore harbour unwanted bacteria.
Also remember that “smells clean, feels clean and looks clean” does not necessarily mean microbiologically clean. Always follow good cleaning and sanitising practices.
TIPS:
• Cleaning scourers are more hygienic than cloths.
• Squeegees should be used wherever possible, instead of mops.
• Cleaning implements made of nylon or similar materials should replace those made of wood or other vegetable matter (such as natural bristles).
• Disposable hand towels are preferable to continuous cloth or forced-air dryers.
• Be sure to clean under and behind appliances such as cash registers and refrigerators; cockroaches and other vermin tend to gather in such places.
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Example of a cleaning and sanitising roster*
| Quality Seafoods Pty Ltd — Cleaning & sanitising roster |
| Monday 3 July to Sunday 16 July |
| TASK |
WHO |
WHEN |
Mon. |
Tue. |
Wed. |
Th. |
Fri. |
Sat. |
Sun. |
| Clean & sanitise floor and walls in retail shop |
John Smith |
Before and after retail hours |
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| Wash tongs trays, etc. in washing sink |
Basil McGregor
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As required
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Clean & sanitise the two display cabinets
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Julie Chapman
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Before and after retail hours
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| Clean & sanitise staff refrigerator |
John Smith |
Tuesday |
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*Management must ensure that cleaning and sanitising staff are comprehensively trained.
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Personal hygiene practices
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Personal hygiene is essential when handling and preparing seafood. Hair, hands and fingernails require special attention as they harbour bacteria that may contaminate seafood.
Place a sign or poster where staff can see it, outlining the following points:
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IS SOMETHING FISHY HERE?
IT COULD BE YOU!
Clean up your act
Keep yourself clean including your clothing, hands, fingernails and body.
Wash your hands of the matter
Wash your hands with soap and warm water:
• immediately before you start or resume work
• after you visit the toilet, smoke, eat, comb your hair or handle a rubbish container, and before and after using a handkerchief or nasal tissue
• Before handling food of a different kind, e.g. cooked, raw, ready-to-eat
Hands off
Do not put your hands or fingers in your mouth, nose, hair, ears or other parts of your body and do not rub your eyes. If any of these are necessary, wash your hands again. Also remove or cover all jewellery, false fingernails and fingernail polish.
The bare facts
Bare hands can readily contaminate seafood, so use tongs or clean disposable gloves. This is particularly important when you handle seafood that will not be cooked or cooked again before serving. Disposable gloves, when worn, should be changed at the times when hands should be washed (outlined above).
Get a handle on the situation
Hold tableware and utensils by their handles and never carry them in your clothing.
Wipe advice
Do not wipe your hands on clothing or on anything other than a clean disposable towel. Forced-air dryers are a poor alternative.
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Do not touch too much
Do not make unnecessary contact with the seafood.
An apron is the answer
Protective clothing such as aprons can prevent food contamination. Only wear such clothing inside the food preparation area, and clean it frequently.
Hair today, gone tomorrow
Hair contains bacteria that can contaminate seafood. Head coverings such as hats, caps, and preferably hairnets must be worn at all times, and must completely enclose the hair.
Stand up for cleanliness
Do not sit or lie on food preparation tables or benches.
Get out of the habit
Do not spit, smoke or chew gum in the food handling area.
Stay away if you are not okay
Do not work in a food handling area if you have a cold, the flu or any other disease, or are affected by sores, boils or an open wound. These infections may be transmitted by contamination of food. Request a change of rosters out of food handling areas if you are unwell. Wear brightly coloured bandages in case they become dislodged.
Mouth off
Do not breathe into any package which will be used for food and never put your mouth on any
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Sound seafood handling practices
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Seafood is frequently handled throughout the supply chain, and the keys to safe and high-quality product are sound seafood handling practices. Seafood hygiene means using seafood handling practices that prevent hazards such as harmful micro-organisms, chemicals and foreign material from making good homes in foods and possibly causing illness in those who consume them.
Poor seafood handling practices can lead to many undesirable effects, including:
• faster rates of spoilage;
• loss of quality;
• shorter shelf life (storage life) of seafood;
• eating of unsafe or poor-quality seafood;
• loss of seafood and of customers.
Some buyers pay more attention to the price of seafood than to the way it has been handled. Yet no matter what the price, seafood poorly handled is not only a waste of money but also a waste of product.
Seafood spoilage cannot be avoided but it can be significantly delayed by always following the “Super Seven of Sound Seafood Handling” (listed below) when receiving, storing, preparing and serving seafood. Similarly, seafood safety risks are significantly reduced by always following the “Super Seven”.
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The super seven of sound seafood handling
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1. Handle carefully
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Always handle seafood carefully, to reduce physical damage. Bruising will cause changes in flavour and texture. Broken and exposed flesh can cause a quickening of bacterial spoilage through contamination, and/or an increase in the rate of enzymatic deterioration, oxidation and dehydration. Never bend product while it is in rigor or the flesh will gape.
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2. Sort, grade and separate
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Sort seafood by separating according to species, batch, to whether it is raw or cooked, and to physical condition (for example, damaged or undamaged). Grade the seafood according to size and quality.
Avoid cross-contamination by keeping separated live, raw, prepared, cooked, and ready-to-eat seafood.
Use separate areas, utensils and containers for different types of seafood. For example, utensils used for raw seafood should never be used for cooked seafood. Colour coded utensils and containers can help prevent cross-contamination.
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3. Keep it clean
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Rinse seafood (except dried or smoked) under cold, running portable water before preperation (using iced, salted water lessens temperature rise and flavor loss). In addition, the equipment used, any surfaces that come in contact with seafood, and the people handeling the seafood must be appropriately cleaned and sanitises. This removes forigen matter, limits the spread of bacteria, avoids cross-contamination, and maintains the product's visual appeal.
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4. Keep it cool
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Chilled seafood must be stored in a clean, tidey enviroment between -1°C and +4°C (if not live) and frozen seafood at -18°C or below. This helps control the build-up of bacteria and the harmful action of enzymes - higher temperatures mean shorter shelf life. Allways use a calibrated thermometer to check the temperature.
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5. Keep it covered
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Seafood must be covered to prevent contamination and damage, and to slow the rate of oxidation and dehydration.
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6. Keep it moist
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Seafood must be kept moist to minimise weight loss and to prevent dehydration, which can adversely affect its appearance, texture and flavor.
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7. Keep it moving
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Keep seafood moving by:
• using it as soon as possible;
• soring it as soon as it is received;
• using a good storage rotation system (first in first out);
• preparing it as soon as it is thawed or removed from the chiller;
•serving it, or returning it to the storage facility, as soon as it is prepared.
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All these pratices, together with quick cooking at high temperatures, help prevent contamination and build-up of bacteria. However, sound seafood handleing pratices are not limited to the "Super Seven". Other factors, for example the material from which fish contact surfaces are made, will either favor or hinder hygiene.
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In the day-to-day operations of a business that handles seafood, decisions need to be made about product quality. How can higher-quality product be distinguished from lesser-quality product?
Lesser-quality seafood is seafood that has suffered some obvious spoilage or damage. It may also have dubious labelling or documentation associated with it. Chemical changes in the flesh that accompany spoilage can be identified and measured using laboratory tests. However, sensory analyses (i.e. using our senses such as sight and smell) are far more useful for deciding on quality in the marketplace or kitchen, and are therefore presented here.
Sensory quality assessment checks vary for different types of seafoods. However, some checks can be generally applied to all seafood and these are listed in the table on the following page. This table should be used in conjunction with the more specific tables for each seafood type that appear on the pages following. There are also tables covering dried, frozen, smoked and canned or bottled seafood.
The tables all describe the “higher quality” and “lesser quality” attributes of seafood products. Generally, the following guidelines can be applied:
• higher quality—the seafood can be safely kept at an appropriate temperature for a time based on the product’s shelf life
• mixture of higher quality and lesser quality—the seafood should be eaten almost immediately, or discarded (depending on which criteria are “lesser”)
• lesser quality—the seafood may need to be discarded in some cases (when in doubt, throw it out). Contact your supplier immediately.
There are four main sensory quality criteria for seafood:
• appearance (look)
• odour (smell)
• texture (feel)
• taste (taste)
Seafood with any of the following attributes should be discarded:
• unpleasant appearance (lesions, ulcers, yellow slime, etc.)
• foreign, unpleasant or unknown odours
• texture soft and mushy
• foreign, unpleasant or unknown flavours or significant loss of flavour
Texture and taste checks are not always possible until after a seafood product is purchased. In most cases, it is against food safety laws for a consumer to touch or handle seafood before purchase. But a seafood’s appearance and odour can give major clues to its quality.
When deciding on the quality of seafood, it must be remembered that quality is determined by examining both the product itself and its surrounds (such as containers or ice). Other factors such as the way in which the seafood was caught, chilled, stored and displayed will also affect its quality. Although not included in the following tables, these “non-product” attributes should be taken into account when deciding on the quality of particular seafood.
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All seafood
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
| Physical damage |
Undamaged external surfaces (e.g. eyes, fins, mouth, scales, shells, claws or legs are intact) |
Some physical damage visible (e.g. broken tail or some bruising) and/or dried out external surface |
Damage is usually caused by rough handling, which may result in lower flesh quality (e.g. if prawn legs are missing, the flesh quality may still be good). Curled or dried-out seafood can result from freezing. |
| Foreign matter |
No foreign matter present |
Any foreign material (such as sand, mud, seaweed, grease, insects, cigarette ash, etc.) on external surface or gills, or in body cavities (must be able to be removed) |
Foreign matter such as physical contamination can also be a safety issue. |
| Overall appearance |
Glossy, shiny, moist |
Dull, washed out (whitening of surface slime) |
Most freshwater finfish have more natural surface slime than marine species. |
| Colour |
Bright, matching the species’ natural colour; slime clear if present |
Faded, unnatural, blotchy; slime turning white |
Blotching can occur through poor handling at harvest. |
| Firmness |
Firm-looking flesh; shell intact |
Indentations or depressions in flesh; shell broken |
Rigor or non-rigor may be present in whole finfish. |
| Packaging |
Intact; plainly labelled to identify product |
Damaged; poorly labelled |
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| ODOUR |
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Fresh sea smell, no unpleasant odour
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A distinct “fishy” smell; slight ammonia and/or garlic smell
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Sharks and rays, in particular, can develop a strong ammonia smell if handled incorrectly. They may need to be discarded.
The natural odours of species differ. |
| TEXTURE |
| Moist, firm and elastic |
(springs back quickly when pressed lightly) |
Slight tears; loss of elasticity |
Some species are naturally softer than others.
Shortly after death, the soft body becomes stiff. This result of rigor mortis can last for hours. Decomposition starts after rigor mortis has finished, when the flesh relaxes. |
| TASTE |
| Flesh or other edible parts |
Natural flavours |
Most natural flavours still remain |
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Finfish — whole or fillet; chilled or thawed
The quality assessment checks listed below are specific to finfish; some entries (e.g. gills) relate only to whole finfish, and others (e.g. flesh colour) relate only to fillets. The eyes, gills, scales and slime of finfish, generally deteriorate faster than the flesh. Refer also to the general quality assessment checks for all sensory criteria (opposite), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
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Bright red |
Beginning to brown |
Not all finfish have red gills. Red around the gills may be blood, which can be a result of the catching method. |
| mucus |
Translucent, very thin film |
Beginning to colour (pink, yellow, brown), clot and thicken |
Mucus can be washed out so care needs to be taken if using it as a quality indicator |
| Gut cavity (if gutted) |
Well cleaned, no protruding bones, lining intact |
Some yellow or green staining; some torn lining; bones beginning to protrude |
If bloodline present, the blood should be bright red.
Lining can be torn during gutting. |
|
|
Pupil jet-black, shiny, and well defined
Cornea translucent |
Pupil becoming dull and grey
Cornea cloudy, opaque or slightly blood-stained |
Finfish eyes can be damaged in numerous ways, and lesser-quality eyes do not necessarily signify poor-quality flesh.
Eye cloudiness can result from not icing the fish correctly or fish being in an ice slurry too long. Thawed finfish can have opaque or cloudy eyes as a result of ice harming the structure of eye tissue. |
| shape |
Lens smooth and bulging (convex) |
Lens sunken (concave) or “pushed in” in the centre |
Check both eyes—one may be sunken due to physical damage and the flesh may still be of higher quality. Bulging eyes can be caused by pressure changes during capture. |
|
|
Firmly attached to any bones, free of gaping |
A few rips, bruises or blood spots; slightly dried-out, ragged edges if cut; separating from bones; slightly gaping |
With fillets, also consider (where relevant) clean skin removal, size consistency, and cutting or trimming imperfections. |
| colour |
Variable (white, grey, pink, red, orange, etc.), but usually shiny, translucent; bloodline bright red |
Bleached white, opaque; colourbeginning to yellow or brown (i.e. red to brown); wrinkled surface or white cottony patches |
Flesh tends to dull and yellow with age. Dry cottony patches or wrinkled product surfaces result from dehydration (known as “freezer burn” when severe). |
Prawns — uncooked or cooked; chilled or thawed
The quality assessment checks listed below are specific to prawns. Refer also to the general quality assessment checks for all sensory criteria (p. 184), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
|
|
Head firmly attached, not squashed |
Head loose; body may be soft and slightly broken |
Soft and broken shells may not be an indicator of poor eating quality; the shell may be soft because the prawn has just moulted.
The tail being tightly curled underneath and a little separation between the flesh and shell mean that the prawn is cooked; they are not indications of any health risk.
Intact antennae can indicate that the prawns have not been frozen. |
| colour |
Bright, glossy, without signs of fading |
Beginning to darken around the edges of the body segments, legs, shell, flesh, gut or head areas; some fading (particularly with certain species); dry, bleached areas |
Black spot or brown head need not mean that the flesh quality has been affected.
Yellowing around legs can be caused by excessive use of metabisulphite, which is used to control black spot.
A dark intestinal tract can indicate roe. |
| TEXTURE |
|
|
Firm, but not exposed if shell-on |
Soft, slimy or gritty (if raw); chewy, soft or watery (if cooked) |
Grittiness can be a result of undissolved metabisulphite. Overuse of metabisulphite can be a safety issue.
Large prawns are not always tougher than small prawns. Tough texture can be caused by overcooking or being held in brine too long. Prawns can become soft and watery after freezing and thawing. |
| TASTE |
|
Sweet and distinctive prawn flavour |
Salty, or reduction of distinctive prawn flavour |
The saltiness of a prawn can reflect the amount of salt the prawn has been exposed to (for example in cooking or storage). Saltiness can hide a lack of flavour. Overuse of metabisulphite can result in a slight chemical flavour. |
Crustaceans (excluding prawns) — uncooked or cooked; live; chilled or thawed
The quality assessment checks listed below are specific to crustaceans other than prawns. Please refer also to the general quality assessment checks for all sensory criteria (p. 184), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
|
|
Legs move when touched; rocklobster tail curls under when the animal is picked up |
Little movement; rocklobster tail hangs limp when the animal is picked up |
More vigorous movement signifies better quality. Chilled animals will move less and be slightly limp.
Dead, uncooked (raw) crabs should not be purchased as it is very difficult to assess how long ago they died.
If the tail of a rocklobster or freshwater crayfish does not curl under the head when cooked, it could be undercooked or not “fresh” when cooked. |
|
|
Not cracked, no missing body parts |
Some cracks, and releases large amounts of liquid when shaken (especially when cooked); some missing body parts |
If cracked, the flavour and texture of the flesh can be damaged by water during cooking. If the flesh is dry, the animal has probably “bled” or been overcooked. |
| colour |
No discolouration; most are bright red or orange when cooked |
Black discolouration beginning to form at the mouth, head or base of tail |
Discolouration often occurs first at the joints. |
|
|
Translucent when raw; opaque when cooked; no brown staining |
Green, yellow, brown and/or with dark spots when raw; creamy, yellow or grey when cooked; slight brown staining at top of tail (not in crabs) |
Living environment can affect flesh colour, and the flesh of some species has a yellow tinge. Crab claw meat tends to be darker, and is often not used where presentation is important.
Chop off brown-stained area at top of tail if necessary. |
| ODOUR |
|
Pleasant smells, virtually odourless |
Beginning to smell like seaweed or garlic when uncooked; slight ammonia smell when
Pleasant smells, virtually odourless cooked |
Smell is a reliable guide to quality. Meat in the carapace will go “off” first because it has closest contact with the guts. For crabs, lift up the abdominal flap to check the smell.
Any mud or other foreign matter should be removed before checking odour. |
| TEXTURE |
| Shell |
Hard (unless a soft shell crab product) |
Soft (unless a soft shell crab product) |
Check for softness by firmly pressing the underside of the shell near the base of the claw. (Note: if the animal has moulted recently, the shell will be softer.)
Mud crabs are naturally harder than blue swimmer and spanner crabs.
Weight can be an indication of value for money, but is not necessarily a guide to quality. A light weight usually means that the animal has moulted recently and lacks meat content. Crab shells should sound heavy and full when lightly tapped. |
| Flesh |
Moist, firm and juicy |
Some dryness; slightly chewy or tough |
If the crustacean is stressed the meat may toughen. Undercooking leads to mushiness, overcooking usually results in tough flesh. If the animal has moulted recently, the flesh tends to be softer and not as stringy. |
Mussels, oysters and other bivalves — live or uncooked; shucked and chilled
The quality assessment checks listed below are specific to bivalves. Please refer also to the general quality assessment checks for all sensory criteria (p. 184), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
| Shell |
Clean, intact |
Chipped or dirty |
Mussels have byssal threads that are used to attach the mussel to a surface. These may be present but do not affect the eating quality.
In live animals, gaping shells suggest that the animal is dead or dying and should be discarded (it may have been in this condition for some time and could be contaminated). |
| Liquid (liquor) |
Clear |
Slightly opalescent (oysters), or slightly milky in colour |
|
|
|
Juicy, moist, plump and firm
|
Starting to shrink and look flat |
Oysters are often turned over when shucked to give a “plump” look. |
| colour |
Mussels are usually white or orange; oysters vary naturally from greenish grey to white or ivory |
Mussels fade; oysters darken (but may be a brilliant white or greenish) |
Living environment and feed can influence flesh colour.
Mussels range from cream to pale or deep orange with a black rim. Female mussels are orange in colour; males are whitish.
To determine if an oyster shell is original or re-used, check for a muscle remnant. In a “freshly” opened oyster, presented on a half shell, the muscle that attaches the flesh to the shell will have been cut, and the flesh turned over. When the shell is re-used, it is cleaned and the muscle remnant removed. Note re-using shells can be a health risk, and may be in contravention of food laws. |
Scallops — uncooked; shucked and chilled or thawed
The quality assessment checks listed below are specific to scallops. Please refer also to the general quality assessment checks for all sensory criteria (p. 184), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
|
|
Varies from white to cream |
Tan or orangish brown |
Tanning (yellow to orange colouring) suggests ageing product. Such colour does not always mean the flesh is bad, but it must be considered suspect. Pink colouration can indicate spawning, having been in the shell too long or staining from contact with roe. |
| Roe |
Fleshy, firmly attached |
Loosely attached |
Colour varies with species. The presence of roe does not affect the eating quality of the scallop meat. Most consumers like the meat with the roe attached. Saucer scallops are usually sold roe off. |
| ODOUR |
| Overall odour |
Distinct, strong scallop smell (especially in saucer scallops) |
Sour, unpleasant smell |
The distinct scallop smell of high-quality product is sometimes mistaken for lower quality by the uninitiated. |
| TEXTURE |
| Edible parts |
Moist, firm and elastic |
Soft, flabby, break up easily; high loss of water (drip loss) |
Soft scallops and those with high water content may have been soaked in water to increase their weight.
Crumbed, battered or otherwise coated scallops can “explode” when deep fried. |
Squids, cuttlefishes and octopuses (cephalopods) — uncooked; chilled or thawed
The quality assessment checks listed below are specific to cephalopods. Please refer also to the general quality assessment checks for all sensory criteria (p. 184), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
|
|
Intact, with distinct patches of iridescence in squids and cuttlefish |
Some tears in the skin, some broken arms |
If trawled, the skin may have been rubbed off or torn; this does not necessarily indicate poor-quality flesh.
Ink on a squid or cuttlefish does not mean poor eating quality, but is a warning of poor handling. It can encourage bacterial growth and should be washed off immediately. |
|
|
White, slightly translucent when raw |
Darkens to a strong pink tinge |
When “freshly” caught, squid have an attractive translucent flesh. If you put your fingers inside the tube, you should be able to see them clearly. After death, chemicals are released that discolour the flesh.
This process can be aggravated by damage to the internal organs through rough handling. Discolouration is clearly visible when the skin is removed. |
| TEXTURE |
| Flesh |
Elastic, very firm, not slimy |
Loss of elasticity, soft, slimy or gritty |
Squid and cuttlefish are often perceived as being overly tough. The flesh is naturally firm but can be toughened by incorrect cooking or overcooking.
Grittiness can be caused by foreign matter such as sand.
Octopus is naturally firmer than squid and cuttlefish. |
Dried seafood such as beche-de-mer
Please refer also to the general quality assessment checks for all sensory criteria (p. 184), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
|
Free of slime and mould; clean; no cuts, not squashed |
Patches of powder, mould or slime; cuts; squashed |
|
| ODOUR |
| |
Typical of product, varies from very little to very strong |
Unusual odours |
|
| TEXTURE |
|
No moisture |
Slightly soft and mushy |
|
Sea urchin
Please refer also to the general quality assessment checks for all sensory criteria (p. 184), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
|
Rich orange, yellow or brown colour |
Slightly dull, “sticky” appearance; irregular darkening; drying at edges |
Colour is somewhat dependent on species, sex and time of harvest. |
| ODOUR |
|
None, or faint “sea” smell |
Increasing odour |
|
| TEXTURE |
|
Texture obvious |
Texture becoming less evident |
|
| TASTE |
|
Strong, sweet, pleasant |
Lacking sweetness |
|
Frozen seafood
A thorough assessment of the quality of frozen seafood is not possible. A few characteristics can be checked, but only when the product is thawed can a more thorough assessment be made.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
| All |
Evenly frozen, no ice crystals |
Ice crystals built up within the gaps in the flesh |
Raised edges and ice crystals between muscle segments indicate that the original product was frozen slowly, not in prime condition or that it has been thawed and refrozen. |
| colour |
Bright and glossy, particularly cut surfaces |
Slightly dull and discoloured (bleached, yellow, brown or black spots)
Slightly dried out edges; some cottony patches |
Properly frozen seafood will retain much of its colour. Bruising can cause black discolouration.
Dehydration can result in freezer burn—bleached spots, papery or cottony edges and a dry texture.
Oxidation causes the flesh to turn yellow and then brown.
Dehydration and oxidation are not health hazards but do indicate poor eating quality. |
| packaging |
Tight wrapping, moisture-proof wrapping, undamaged; glazing intact |
Slightly dull, “sticky” appearance; irregular darkening; drying at edges |
Generally, damaged packaging indicates rough handling and the entry of air. It is advisable not to buy frozen seafood that is poorly packed. Ice build-up inside a package indicates temperature fluctuation. |
| ODOUR |
|
Clean, fresh smell; virtually odourless |
A distinct “refrigerator” smell |
An odour in frozen seafood suggests quality problems, and a closer inspection is required. The colder the seafood, the less odour it emits. |
| TEXTURE |
|
Hard |
Signs of partial thawing (soft edges and a build-up of moisture) |
|
Smoked seafood
Please refer also to the general quality assessment checks for all sensory criteria (p. 184), which cover all seafood.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
|
|
Even, bright, glossy, golden; yellowish red or gold |
Dull or matt, uneven; discoloured, fading |
Colour is an unreliable guide to quality if considered in isolation. The colour depends on, for example, the original colour of the seafood, the degree of smoking, whether hot or cold smoking has been used, and whether a dye has been used to enhance its appearance. Cold-smoked seafood is often lighter in colour than hot-smoked seafood. |
| condition |
Smooth intact pellicle, free of contaminants |
Pellicle slightly damaged; bruising or mould growth |
The loss of pellicle (thin skin) integrity may indicate poor handling. |
| ODOUR |
|
Clean, smoky aroma |
Reduction of smoky aroma |
Smoking may mask bad odours, flavours and defects to a certain extent, but they will still be evident.
Be especially wary of unusual smells in smoked seafood—they usually indicate bad preparation or handling, or poor original quality. |
| TEXTURE |
|
Firm and springy |
Sticky, soggy, soft patches or flabby |
Soft patches can be caused by parasites. |
| TASTE |
|
Mildly smoky, perhaps salty |
Reduction of smoky flavour, slight presence of foreign flavours or overly salty |
Foreign flavours can occur when poor-quality product has been smoked. |
Canned, bottled (including pickled) and tubbed seafood
The information provided here is very general and more specific quality assessment checks are required for different products.
| Check |
Higher quality |
Lesser quality |
Comment |
| APPEARANCE |
| Can/bottle/tub |
Clean, undamaged |
Slightly dirty, undamaged |
Dented cans may be acceptable as long as the seams are not damaged (top, bottom or sides). However, it is best to avoid them for safety reasons.
Canned, bottled and tubbed products should be consumed quickly after opening. If not (for example if kept overnight) they should be stored in a sealed container. |
| Flesh |
Holds together |
Falls apart |
|
|
|
Usually clear, otherwise typical of ingredients |
Cloudy or foggy; changing colour |
|
| quantity |
Variable depending on the product, but usually totally covering the seafood |
Not covering all the seafood |
|
| condition |
No suspended matter |
Suspended matter, such as small pieces of product, floating in the liquid |
|
| ODOUR |
|
Good, salty sea smell, or typical of the species and pickling liquid |
Slightly objectionable odour immediately on opening |
|
| TEXTURE |
|
Rich in natural flavour; or typical of the species and pickling liquid |
Weak; loss of flavour |
Often the seafood will have absorbed the liquid and may therefore have little flavour. This only affects eating quality and is not a health hazard. |
|
|