Food tech (condensed)

outline the characteristics of enzymes

outline the characteristics of enzymes

• Enzymes cause food spoilage

• they are catalysts for chemical reactions

• they cause browning in certain foods called enzymic browning

• enzymes can be destroyed by heat or acid

• They cause food to spoil by oxidation

how can you prevent oxidation when cooking?

• adding an acid

• cooking immediately

• protect from light

• add antioxidants

• refrigeration

outline the characteristics of yeast

• they prefer acidic foods

• As yeasts ferment the sugars in these foods , they produce alcohol and carbon dioxide

• can grow with or without oxygen

• Spoil fruit, juices, jam and honey

outline the characteristics of moulds

• grow best at 20-30 C

• damp air and warm temperature can speed up mould growth

• they grow throughout the foods to get all the nutrients

• grow easily on bread, cheese, jam, and soft fruits

how are moulds used in food production?

To make cheese: Starter culture is added to change lactose to lactic acid. This gives the correct level of acidity and gives the cheese moisture. The mould gives the cheese a smell, taste and texture.

To make yogurt

how is yeast used in food production?

To produce bread, beer and wine.

Yeast ferments or breaks down glucose into alcohol and carbon dioxide.

how is bacteria used in food production?

Making cheese: Starter culture is added to ripen the cheese and creates curds and whey.

how is mould used in cheese production?

To make blue cheese: creates blue veins within the cheese

To make soft ripened: mould grows on the outside causing the cheese to age from the outside in

how do you use a food thermometer probe?

1. Clean and disinfect the probe before use

2. Insert the probe to the centre or thickest part of the food

3. Wait a few seconds for the display to stabilise before taking a reading

4. Read the temperature

5. Check the food has reached 75 C

6. Clean and disinfect the probe after use

What are the 14 common food allergens?

• gluten

• celery

• tree nuts

• fish

• soy

• sesame

• peanuts

• crustaceans

• eggs

• molluscs

• milk

• mustard

• sulphur dioxide and sulphites

• lupin

what is sensory evaluation?

Judging the different sensory qualities of food.

why do we carry out sensory evaluation?

• ensure food meets a customer’s expectations, so people will enjoy the foods

• ensure changes to the product remain acceptable

• it guarantees food products remain consistent over time

• compare to other products to get ideas for improvements

• ensures food products meet the original specification

• to monitor the quality and shelf life of products over time.

what is a paired preference test?

A person is given two samples and is asked which they prefer

What is hedonic ranking?

This is a type of preference test that finds out if people like or dislike a product/s.

They rank the samples on how much they like them.

what is the triangle test?

This is used to detect differences in two samples, a person is given three sample, two are the same, and they have to find the odd-one out.

what is the ranking test?

Looks at a particular sensory property in a number of samples.

what is the rating test?

Allows people to rate different sensory properties of a food.

how do you create a fair testing environment?

• distractions including smells should be removed

• lighting should be controlled and coloured lighting should be used if there are visual differences between samples

• seating should isolate testers

• water should be provided to allow the sampler to cleanse between samples

What do cholesterol lowering products contain?

Natural extract from plants which stops cholesterol from being absorbed into the bloodstream

What are the disadvantages of a preservative?

some can be linked to a higher risk for developing cancers

What are the disadvantages of flavouring?

Can cause symptoms similar to an allergic reaction

What are the disadvantages of an emulsifier?

• Can cause liver disease

• some people report flatulence and bloating

What are the disadvantages of stabilisers?

• Damage to internal barrier

• some people experience flatulence and bloating

Describe the muscle tissue in meat.

It is made up of long thin fibres which are held together by connective tissue. These are either collagen, which holds bundles of fibres together or elastin, which binds the muscle together or the fibres to the bone.

what happens to collagen during slow, moist cooking methods?

it is converted to gelatin which is a soluble protein which is soft and tender and easier to eat and digest.

What nutrients are found in meat?

Protein.

Red meat contains Iron,Zinc and B vitamins.

Describe the muscle tissue in fish.

The muscle fibres are found in short blocks with no elastin and only a thin sheet of connective tissue surrounding them. This ensures it is relatively tender and only requires a short cooking time.

What nutrients are found in fish?

Vitamin D and B2 and Omega 3 and 6

what nutrients are in vegetables?

vegetables which grow above ground are a source of vitamin C

seeds and pods contain protein, dietary fibre and some vitamin C

vegetables that grow below ground contain carbohydrates and fewer vitamins

What is the classifications of cereals?

• Wheat

• Rye

• Rice

• Maize

• Barley

• Oats

what is white flour fortified with?

Calcium, Iron, Vitamin B1 and B3

what is semolina?

a course-ground flour, which comes from wheat

what is durum wheat?

a yellowy, high-protein wheat that is grown especially for pasta-making.

what is the structure of semi-skimmed milk?

• 88% water

• 5% carbohydrate

• 3.5% protein

• 1.5% vitamins and minerals

• 1.7% fat

How is milk turned into cheese?

1. Pasteurise the milk: Destroys bacteria, makes milk ready for starter culture. Milk is cooled

2. Add the starter culture: starter culture added to ‘ripen’ the milk. Lactic acid bacteria change lactose into lactic acid. Temp is 25-35C for 30 mins.

3. Add rennet: This helps the milk coagulate. Milk turns into curd and whey. Takes 30 mins

4. Cut curd and heat: curd is cut with cheese knives into small pieces. Different temps make different types of cheese. Soft cheeses are made from soft curds at lower temps.

5. Drain whey: Whey is drained and the curds form a mat

6. Texture curd: Curd mats are cut and piled on top of one another. Cheddaring removes more whey and allows the mats to ‘knit’ together in a tight structure.

7. Salt: salt is added to produce the right texture and flavour

8. Form into blocks: Salted curd is placed into cheese hoops and pressed into blocks

9. Store and age: cheese is stored in coolers until the desired age is reached

10. Package: cheese cut and placed into blocks. Wax, foil, paper, plastic and cloth can all be used to protect cheeses

How is milk turned into yogurt?

1. Pasteurise the milk: Pasteurised milk is homogenised so fat droplets are dispersed. Less bacteria so ready for starter culture

2. Warm the milk: Milk is warmed to 42C

3. Add the starter cultures: Lactic acid bacteria is used for starter culture. Ripening lets lactose to lactic acid

4. Hold: Milk is held at 42C. Fermentation creates a soft gel as protein sets

5. Cool: yogurt is cooled to 7C. fermentation stops

6. Add flavour: fruits and flavours are added

7. Package: pumped from fermentation vat to pots. Chilled to below 5C

How is fruit turned into jam?

1. Select fruit: under-ripe fruit has more natural pectin

2. Prepare fruit: wash and drain the fruit and remove any bruised fruit or seeds/stones/stalks

3. Add water and acid: simmer the jam. pectin is released from fruit with the help of the acid

4. Add sugar: stir gently to dissolve sugar completely

5. Add pectin: add liquid pectin, if the fruit is low in natural pectin

6. Boil: a full,rolling boil is required. Stir frequently

7. Test and pour into jars: setting point for jam is 105C. Use the wrinkle test to ensure this point has been reached. Pour into sterilised jars

what are the effects of canning on food?

Destroys some vitamin C and B groups as they are sensitive to heat.

what are the effects of drying on food?

destroys some vitamin C and B groups but makes vitamin A and E more concentrated in a product

What is the recommended amount of sodium?

A maximum of 6g for an adult daily.

Children under 11 years should eat less.

What is the function of vitamin B12 ?

Maintains nerve cells

Helps make new red blood cells

Releases energy from foods

What is the function of Folic acid ?

Reduces birth defects in unborn babies

Helps form healthy blood cells

What is the function of vitamin C/ Ascorbic acid ?

Needed for healthy connective tissue, production of collagen

Helps wounds heal

Helps in the absorption of iron

Is an antioxidant

What are the sources of vitamin B1/Thiamin ?

• wholegrain products

• meat

• milk and dairy

• Nuts

• Marmite

• Fortified breakfast cereals

• Fortified white/brown flour

What are the sources of vitamin B2/Riboflavin ?

Chicken

Eggs

Milk

Fish

Leafy vegetables

What are the sources of vitamin B3/ Niacin ?

• Red meat

• Poultry

• Fish

• Brown rice

• Nuts and seeds

What are the sources of vitamin B12 ?

Meat

Eggs

Milk

Salmon

Fortified breakfast cereals

Marmite

What are the sources of Folic acid ?

Fortified breakfast cereals

Broccoli

Brussel sprouts, Green leafy vegetables

Chickpeas

Potatoes

What are the sources of vitamin C ?

Citrus foods (lemons,limes,oranges,grapefruit etc)

Blackcurrents

Potatoes

Red/green peppers

Salad and green vegetables

What happens when someone has a deficiency of B1?

They get Beri Beri, a muscle wasting disease

What happens when someone has a deficiency of B3?

They get Pellegra which causes dermatitis,dementia and diarrhoea

What happens when someone has an excess of B3?

Can cause liver damage

What happens when someone has a deficiency of B12?

They get pernicious anaemia.

What happens when someone has a deficiency of Folic acid?

Causes Spina Bifida in unborn babies.

Materials we need in our diets.

• Iodine

• Iron

• Calcium

• Sodium

• Phosphorus

• Fluoride

What is the function of calcium?

• Maintains normal bones and teeth

• allows normal blood clotting

• controls muscle contractions including the heart beating

What are the sources of calcium?

• Milk/dairy products

• Edible soft bones of fish (canned salmon)

• Green leafy vegetables

• Fortified soya bean products

• Bread (fortified in UK)

What happens when calcium intake is too low?

Calcium is withdrawn from bones.

This leads to low bone density which can cause osteoporosis.

This may be caused by a lack in vitamin D which is common in teenage girls.

What is Iron needed for?

• The formation of haemoglobin in red blood cells

• Transport of oxygen around the body

• Function of the immune system

• Normal cognitive function

• Reduction of tiredness and fatigue

• Cell division

What are the two types of iron?

Haem iron.From animal source.This is readily absorbed into the body.

Non-haem iron.From plant sources,fortified foods and supplements.Vitamin C helps the absorption.

What are the sources of Iron?

• Cereals

• Nuts

• Egg

• Fish

• Red Meat

• Green leafy vegetables

What happens with high intakes of Sodium?

It is linked to high blood pressure (hypertension) which increases the risk of stroke and CHD.

What is Phosphorous needed for?

• The maintenance of normal bones and teeth

• The production of energy

What are the sources of Phosphorous?

• Red meat

• Milk/dairy products

• Fish

• Poultry

• Bread

• Rice

• Oats

What is the function of Iodine?

Making the hormone thyroxin which maintains a healthy metabolic rate.

What are the sources of iodine?

• Red meat

• Fish/seafood

• Cereal

What are the symptoms of Iodine deficiency?

Goitre (swelling of the thyroid gland)

What are the functions of water?

• Allows cells to function

• Regulates body temperature

• Helps us get rid of waste

• Allows normal cognitive function

• Decreases blood pressure

• Stops dehydration

• Hydrates skin

• Used in respiration

What are the signs of dehydration?

• Dark urine

• Headaches

• Lack of energy

• Feeling lightheaded

What are the functions of Vitamin A?

• Antioxidant,protects the body

• for growth and development of the body

• making sure skin is healthy

• helping vision in dim light

• keeping the skin and the membranes in the body healthy

What are the two types of Vitamin A?

Retinol, animal sources

Beta carotene, vegetable sources

What are the sources of Vitamin A?

ANIMAL

• eggs

• oily fish

• liver

• full fat milk

what happens when you have an excess of vitamin A?

Can be toxic, causing liver and bone damage.

Excess retinol can lead to birth defects.

What happens when you have a deficiency of vitamin A?

Can cause night blindness

What is the function vitamin D?

• Absorption and use of calcium and phosphorus

• Maintenance and strength of bones and teeth

What are the sources of vitamin D?

• Oily fish

• Meat

• Eggs

• Fortified breakfast cereals

• margarine

• Sunlight

what is the function of vitamin E?

• Antioxidant that helps protect cell membranes

• Maintains healthy skin and eyes

what are the sources of vitamin E?

• Polyunsaturated fats, e.g. sunflower oils

• Nuts

• Seeds

• Wheatgerm

what is the function of Vitamin K?

It helps blood clot or coagulate correctly

what are the sources of vitamin K?

• green leafy vegetables

• cheese

• bacon

• liver

Adolescents needs

Rapid growth and puberty occur at this time. High demand for energy and most nutrients,high protein intake for boys. Girls need more iron than boys because of menstruation.Recommended that teenage girls and women require 14.8 mg of iron each day, while adolescent boys only need 11.3mg of iron per day. A growth spurt begins around 10 years of age in girls and 12 years in boys. For both boys and girls, an average of 23 cm is added to height and 20-26kg in weight. Before adolescence, both girls and boys have an average of 18% body fat, during, this increases to around 28% in girls and decreases to around 15% in boys.

lacto-vegetarian

Someone who doesn't eat meat and eggs

Lacto-ovo vegetarian

Someone who eats vegetables,eggs and dairy products but not meat.

Iron deficiancy anemia

Iron deficiency anaemia is where your body does not produce enough red blood cells because the level of iron in your blood is too low.

Conduction notes

The direct transfer of heat between adjacent molecules.This is when heat travels through solids like food or metal.

For example cooking with a flat top range.

Convection notes

This is the exchange of heat by the application of a gas or liquid current.The movement of heat in water is called a convection current.

For example boiling potatoes.

Radiation notes

This is energy in the form of rays.Grilling involves the use of infrared heat rays created by gas flames.

Microwaves are electromagnetic radiators of high energy and short wave lengths.They quickly heat anything with water.

Cooking with water

Heat passes through water very quickly. It is transferred via conduction and convection.

Methods of cooking with water

Blanching

Boiling

Braising

Poaching

Simmering

Steaming

Cooking with dry heat

Heat passes through the air in convection currents as radiation from a grill.

Methods of cooking with dry heat

Baking

Grilling

BBQ

Deep frying

Cooking with fats

Heat will pass through oil or fat by convection currents or conduction

Low fat spreads cannot be used in frying as they contain water

Methods of cooking with fats

Shallow frying

Stir-Frying

Roasting

6 Marker for Carbohydrates

Explain the scientific process that takes place when making roux sauce

Gelatinisation takes place when starch is added to liquid and is heated until boiling point.This process takes place as starch consists of small granules that are suspended in the liquid as they do not dissolve.The sauce must be stirred whilst heating to ensure that the heat is equal throughout as else the granules will clump together.When heated to around 60 celsius,the starch granules begin to absorb the liquid and swell.When it reaches around 80 celsius it starts to thicken and when it finally reaches boiling point the process of gelatinisation is complete.

Dextrinisation (maillard reaction)

This occurs when starch is broken into dextrin by dry heat. Dextrin adds a sweet taste.

This contributes to the colour and flavour of many foods like crossiants.

Parts of amino acid and sugar molecules in food combine, when heated, to form brown compounds (dextrin) which change its colour, odour and flavour. This is also known as non-enzymatic browning or the Maillard reaction.

Caramelization

It is one of the most important types of browning processes.

It is the process of changing the colour of sugar from white to brown when heated.

It leads to a desirable golden brown colour and an attractive flavour in baked goods and drinks. Caramelisation can give a buttery, toasty or even a nutty flavour to food

Shortening

The fat coats the flour particles and prevents them from absorbing water.This reduces the gluten development,which would cause the dough to become elastic.

Used in shortcrust pastry,biscuits and shortbread.

Aeration

This is achieved by creaming a fat with caster sugar.

Small bubbles of air are incorporated and form a stable foam which can be baked to give the springy texture.

Used in creamed cakes.

Plasticity

This describes the ability of a solid fat to soften over a range of temperatures.Fats do not melt at fixed temps but at a range.

This plasticity is due to the mixture of triglycerides,each with its own melting point.

The two types of emulsions

1. Oil in water emulsion forms when the amount of water is greater than the amount of oil.Tiny droplets of oil are spread throughout the water.E.g milk

2. Water in oil emulsions forms when the amount of oil is greater than the amount of water.Tiny droplets of water are spread throughout the oil.E.g Butter