Home Economics Notes

Flashcards for review

What is the elemental composition of water?

Hydrogen (H) and oxygen (O) in a 2:1 ratio (H2O).

List some properties of water.

Colourless, odourless, tasteless, boils at 100°C, freezes at 0°C, neutral pH of 7, excellent solvent, can be solid, liquid, or gas.

Name three biological functions of water.

Removes waste products, transports nutrients, regulates body temperature, hydrolysis during digestion, prevents constipation.

List some sources of water.

Tap or bottled water, fruits and vegetables, beverages (milk, tea, coffee, juices), soups.

What is the recommended daily intake of water for teenagers and adults?

Females: 2 litres, Males: 2.5 litres.

According to shape, how can fish be classified?

Flat fish (e.g., plaice, halibut, sole) and round fish (e.g., tuna, cod, salmon).

According to habitat, how can fish be classified?

Freshwater fish (e.g., salmon, bream, trout), saltwater fish (demersal e.g. cod, plaice, whiting, and pelagic e.g. mackerel, tuna, salmon), and farmed fish (e.g., salmon, mussels, oysters).

What are myomeres?

Short, thick fibres arranged in broad vertical bands in fish muscle, containing actin, myosin, minerals, vitamins, water, and extractives.

How does the connective tissue in fish compare to that in meat?

Fish has less connective tissue than meat and no elastin, making it more tender, easier to digest, and requiring less cooking time.

Give examples of white fish and state their fat content.

Cod, plaice, whiting and monkfish are examples of white fish. White fish stores all of its fat in the liver. The fat content of their flesh is around 0.5%

Give examples of oily fish and state their fat content.

Mackerel, tuna, herring and salmon are examples of oily fish. Oily fish has fat dispersed and stored between the myomeres and connective tissue. The fat content of their flesh is between 15-18%

Outline the dietetic value of fish

Fish aids with growth and development, white fish is suitable for low-fat diets. Oily fish is recommended for low-cholesterol diets. Available in variety to suit all tastes.

What are some guidelines for buying fish?

Buy from a retailer with a clean and hygienic fish counter, check the use-by date, ensure firm elastic flesh, shiny moist unbroken slime-free skin, tightly attached scales, bright bulging eyes, firm transparent flesh in cuts, and a smell of the sea.

Give examples of what you should consider when storing fish

Store in a fridge at 4°C, leave in original packaging if pre-packaged, rinse and place on a plate or container if purchased loose, cover to prevent drying out, store strong-smelling fish away from foods that absorb flavour, and use within 24 hours.

Name the three main causes of fish spoilage.

Oxidative rancidity, enzymes, and bacteria.

Discuss oxidative rancidity and its cause of spoilage.

Oils in oily fish react with oxygen in the air, causing the fish to become rancid because oxygen combines with the carbons double bonds along the unsaturated fatty acid chain.

Discuss bacterial cause of fish spoilage.

After being caught, fish use up the glycogen in their muscles and liver. This results in little glycogen being left to convert to lactic acid to preserve the fish, which in turn causes rapid deterioration by bacterial action. This produces a strong-smelling nitrogen compound called trimethylamine.

What is cold smoking fish?

Subjecting fish to smoke from wood chips at a temperature not exceeding 27°C. The chemicals creosote and formaldehyde prevent microorganism growth.

What is hot smoking fish?

Similar to cold smoking, but the temperature is gradually increased to approximately 80°C. Fish does not require further cooking.

Give examples of processed fish products.

Fish cakes, fish fingers, and fish extractives (e.g., fish stock cubes).