Past Exam Questions Flashcards
Discuss the nutritive value of fish
/
Discuss the contribution of fish in the diet
7
Source of easily digestible HBV protein - growth and repair - valuable for children, teenagers, pregnant women
White fish = no fat - low in kilocalories - calorie-controlled diets
Oily fish = polyunsaturated fat + omega 3 fatty acids - low-cholesterol diets -increase HDL which lowers cholesterol
Variety of forms - fresh/processed -suits different tastes and adds variety to the diet
Versatile - suited to many different cooking methods and flavour combinations e.g. chilli and lime
Some are inexpensive e.g. mackerel - economical food - processed fish products are cheaper - fish cooks quick - minimising energy costs
Lacks carbohydrates - combine with foods rich in carbohydrates
List the main causes of fish spoilage
Oxidative rancidity
Enzymes
Bacteria
State why oily fish is recommended for the diet of a person with coronary heart disease
Oily fish = polyunsaturated fat + omega 3 fatty acids - low-cholesterol diets -increase HDL which lowers cholesterol
Give an account of six key factors that consumers should consider when buying fresh fish and fish products
(12)
Buy from a retailer with a clean and hygienic fish counter - strict food hygiene and safety policy - ensure fish is safe for consumption
Check the use-by date on pre-packaged fish - it isn’t safe to eat after this date
Ensure fish has firm, elastic flesh,
Skin should be shiny, moist, unbroken and slime-free (indicator of bacterial growth)
Scales should be tightly attached and not loose
Ensure fish have bright and bulging eyes
Gills should be bright red
Firm, transparent flesh with no discolouration such as bruising
Shellfish should feel heavy for their size
Mollusc shells should be closed or close when touched - opened means they are dead and not edible
Crustaceans should be alive to reduce the risk of food poisoning as they spoil quickly when dead
Buy fish near the end of the shopping trip to minimise the amount of time it spends at room temperature before returning it to a fridge
What is cold smoking of fish?
3
Cold smoking involves subjecting fish to smoke from wood chips
The chemicals creosote and formaldehyde in the smoke prevent microorganisms growth on fish flesh
The temperature foes not go beyond 27 degrees so the fish must be cooked before being consumed
What is hot smoking of fish?
2
Hot smoking is cold smoking but the temperature is gradually increased to approximately 80 degrees
Fish does not need to be further cooked to be consumed
Name three different types of processed fish products and state why these products are popular
Fish cakes
- made from minced fish, potato, herbs and seasoning
- shaped into rounds, coated in breadcrumbs or batter
- briefly fried then frozen
- contain 35-45% fish
Fish fingers
- made from blocks of frozen, filleted white fish e.g. cod
- cut into fingers, dipped into a batter or breadcrumbs and refrozen
- contain 50-70% fish
Fish extractives
- fish stock cubes
- made from fish juice extractives that are dried and mixed with cornflour, salt, yeast extract and flavour enhancers
Classify fresh fish and give one example of each class
White fish
- cod
- plaice
- whiting
- monkfish
Oily fish
- mackerel
- tuna
- herring
- salmon
Shellfish
- molluscs e.g. mussels and oysters
- crustaceans e.g. lobster and crab
Outline the main causes of fish spoilage
(Oxidative rancidity)
(2)
Oils in oily fish react with oxygen in the air
Oxygen combines with the carbons in the double bonds along the unsaturated fatty acid chain, causing the fish to become rancid
Outline the main causes of fish spoilage
(Enzymes)
(2)
Naturally present enzymes in fish cause its flesh to deteriorate, even at low temperatures
This can be slowed by placing fish on ice or in the fridge
Outline the main causes of fish spoilage
(Bacteria)
(3)
When fish are caught they struggle frantically, using up the glycogen in their muscles and liver
This results in little glycogen being left to convert to lactic acid and preserve the fish, which in turn causes rapid deterioration by bacterial action
This produces a strong-smelling nitrogen compound called trimethylamine
