food technology’s top 30libvolume2.xyz/biotechnology/semester7/food... · eggs, fish and seafood,...

April 2006 C. Budge 1

Food Technology’s

Top 30

Revision Slides


Slides content

3 – Food choices4 – Dietary goals5 – Individual needs6/7 – Hygiene and safety in the

food industry8/9 – Quality10 – Properties and functions of

food ingredients11 – Heating and nutrition changes12 – Cereals13 – Fruit and vegetables14 – Meat, poultry, fish15 – Fats and oils16- Milk, cheese and dairy17 – Eggs

18 – Sugar19 – Methods of cooking and

transfer of heat20 – Raising agents21 – Setting ingredients22 – Additives23 – Components of foods24/25 – Preservation26 – Smart foods27 – Systems and control28 – HACCP29 – Jobs in the food industry30 – Product analysis


Nutritional needs and Food ChoicesFood Choices

• Food provides us with a variety of nutrients to keep us healthy

• We need to eat a balanced diet. The nutrients we need are:� Proteins – body building, growth and repair� Carbohydrates and fats – supply the body with energy� Vitamins and minerals – protective, keep us healthy• Food labels provide nutritional information – this is important:� Comparisons of the nutritional content of different products� People may be on special diets e.g. low fat� Allows informed choices and that they have a variety of nutrients• What affects our food choice?

Cost; Availability of food; Regional variations or where people live; Personal preferences; Lifestyle; Moral beliefs; Storage and cooking facilities; Religious beliefs; Health; Peer pressure; Recent food scares; Food trends; Cultural preferences.


Nutritional needs and Food choicesDietary goals

• DRV – Dietary Reference Values – show the amount of food energy or other nutrients needed by people of different ages

• RNI – Reference Nutrient Intake – the amount of nutrient sufficient for nearly everyone (about 97% of the population)

• EAR – Estimated Average Requirement – is the amount of the average need for food energy or a nutrient – this is an average for a group

• Dietary changes:Reduce fat – in cooking, choose lower-fat versions of food ingredients,

remove visible fat from meat, bacon and poultry

Reduce sugar – used in recipes, avoid very sugary foods

Reduce salt – add less salt to recipes and avoid ingredients that contain a lot of sodium

Increase fibre – eat more wholegrain foods – bread and cereals, more fruit, vegetables, pulses and nuts


Nutritional Needs and Food ChoicesIndividual Needs

• People have different nutritional needs, which change with age and activity

• Food products are designed to appeal to different people

• Groups of people with special dietary needs:

Vegetarians – vegan, lacto Obesity – low fat products

Diabetics – too much glucose in their body

Food allergies – milk, nuts, eggs, fish and seafood, colourings

Coeliacs – allergy to gluten the protein in wheat

Babies – no salt, sugar, smooth texture

Religion – Muslim, Jewish Children – portion size , nutrients and additives


Hygiene and Safety in the food industryPart 1

• Good hygiene is essential throughout the food preparation chain –Choosing and buying food; Transporting the ingredients; Storing food; Preparing food; Cooking food; Keeping food warm or storing it

• Rules and regulations support the preparation of food so that it is safe to eat.

• Health and Safety is an important issue for the manufacturer, retailer and consumer

• The consumer is protected by:� Food acts and regulations� Trading standards officers� Environmental health officers

• Food factories have strict rules for hygiene and food preparation• Environmental issues that should be considered by the manufacturer,

retailer and consumer – packaging, use of chemicals in the manufacturing process, disposal of waste products


Hygiene and Safety in the food industryPart 2

• Bacteria need warmth, moisture, food and time to grow and multiply• Cases of food poisoning are increasing

• Cross-contamination – raw food touching cooked food

• Microbial contamination – occurs when food has been infected by bacteria, moulds and yeasts

• Examples of bacteria – Salmonella, Staphylococcus aureus• Food retail is the point at which food is sold. Includes shops,

restaurants, fast food outlets, cafes, snack bars and vending machines

• Temperature control is an effective way to control bacteria

• Refrigerators – food stored at 5°C

• Freezers – domestic at -18°C, supermarket at -29°C• The food industry monitors temperature during production and

distribution

• Harmful bacteria – destroyed at 70°C for 2 minutes


Hygiene and Safety in the food industryPart 3 - Quality

• Quality assurance and quality control systems ensure that quality food products are available to consumers

• Quality assurance – relates to the specification, hygiene procedures, monitoring waste and sensory analysis

• Quality control – checks might include – weight, measurement, temperature, checks for foreign bodies and bacteria

• The shelf life of a product is the length of time a product will last without deteriorating

• ‘Use by’ and ‘best before’ dates inform the consumer if the food product is safe to eat and is of good quality

• To maintain a good quality - food products must be stored correctly.• Food spoilage will occur if food is not stored correctly or if it has

reached the end of its shelf life

• ISO 9000 – series of international standards – for quality assurance. Gives greater efficiency in quality control systems


Hygiene and Safety in the food industryPart 4 - Quality

• High risk foods – spoil in a short amount of time e.g. meat and fish• Perishable foods – go off or spoil quickly• Low risk foods – have a long shelf life• Dehydrated foods – had the moisture removed• Ambient temperature – normal room temperature - 20°C and 25°C• To avoid cross contamination – use coloured chopping boards and

knives: raw fish – blue; raw meat – red; fruit and vegetables – green; cooked meat – yellow

• Food is processed in a variety of ways in the food industry –assembling food products, application of heat and cold, food preservation and finishing techniques

• Food preservation is used to prolong the shelf life of products• Food preservation – freezing, canning, irradiation, AFD, MAP and

dehydration


Food IngredientsProperties and functions

Food ingredients have a function within a recipe, some may have several

• Coating – chocolate on biscuits• Glazing – egg on top of bread

products

• Aerating – eggs used in a whisked sponge (cake made lighter by adding air)

• Binding ingredients – milk in scone mixture

• Bulking – flour used in pastry• Setting – gelatine used in jelly• Thickening – flour used to

thicken a sauce

• Adding flavour – herbs and spices – to a variety of products

• Emulsifying – egg yolks added to mayonnaise (stops ingredients separating out)

• Preserving – vinegar used to preserve onions (last longer)

• Shortening – lard or vegetable fat will give a crumbly texture

• Sweetening - honey in cakes

• Adding moisture – milk is added to a batter

• Adding texture – nuts in cakes


Food IngredientsHeating and nutrition changes

• StarchDry heat – starch turns to dextrin

Moist heat – starch granules soften and swell and absorb water and thicken liquids (gelatinisation)

• SugarWhen heated sugar dissolves, it

changes from white to golden (caramelises)

• Fats – solidMelt to a liquid, bubble and can

decompose at high temperatures when fats give off smoke and burn

• ProteinDenatures (changes) on heating,

then coagulates and sets

• Vitamins A & D (fat soluble)Not affected by the cooking

process as they are not soluble in water

• Vitamins B & C (water soluble)Are soluble in water and are

destroyed by heat

• NSPSoftens when it is heated with

liquid• MineralsHeating has little affect


Food IngredientsCereals

• Cereals are important foods in our diet• Cereals are used in a variety of products

• The main nutrients – starch, some protein, NSP and some calcium, iron and B vitamins

Types of cereals and products made from themWheat – bread, pasta, pastry, biscuits, pies, cakesOats – biscuits, porridge, oatcakes, bread, muesliMaize – bread, popcorn, sweetcorn, cornflour, polentaRye – rye bread, rye crispbread, muesliRice – noodles, rice cakes, puddings, ready-meals with riceBarley – soft drinks, beer, scones• Some cereals contain gluten which forms the structure of products

such as bread

• Types of flour – wheat, cornflour, potato, rice, arrowroot (tropical root)


Food IngredientsFruit and Vegetables

• We should eat five portions of fruit and vegetables a day

• Fruit and vegetables provide us with vitamin C, betacarotenes, carbohydrates and NSP (dietary fibre)

• Vegetables and fruit need careful preparation to avoid loss of vitamins and minerals

Saving vitamins and minerals:1. Buy good quality and store in a cool, dark place for a short time

2. The nutrients are found under the surface of the skin, so either peel thinly or eat with the skin on.

3. Cook vegetables very quickly in a small amount of water

4. Leave in large pieces to avoid too much nutrient loss from the surface of the fruit or vegetable

5. Try to eat raw fruit and vegetables

6. Don’t leave them to stand in water – vitamin C & B are dissolved


Food IngredientsMeat, poultry and fish

• Meat, poultry and fish are important sources of protein• Also contain – iron, B group vitamins especially B12• They are made into a wide variety of products and ready-meals

• Meat is cooked – to kill bacteria, make it tender to eat and improve its flavour

• Cooking methods – dry – grilling, roasting, baking, frying• Cooking methods – moist – stewing, boiling, pressure cooking, casseroling• Cooked meat and raw meat should be stored separately – to avoid

cross-contamination

• Poultry – protein, lower in fat and more tender than meat• Chicken – thoroughly cook to kill off any Salmonella bacteria

• Fish – white, oily and shell• Fish – good source of protein, B group vitamins, iodine and fluoride• White fish – low fat. Canned salmon and tuna – good source of calcium


Food IngredientsFats and oils

• Fats and oils contain mainly fat, some contain vitamins and essential fatty acids

• F at should provide no more than 35% of food energy

• Butter and margarine – 80-82% fat. Used for spreading, baking, shallow frying, pastry, sauces

• Reduced fat margarine/spread – 60-62% fat. Used for spreading, all-in-one cakes, sautéing, short crust pastry, sauces, scones

• Half-fat butter/margarine/spread – 39-41% - Used for spreading, sautéing, sauces, scones, choux pastry

• Low fat/light spread – less than 40% - spreading• Other fats used in cooking – lard, suet, dripping• Margarine is fortified with vitamins A and D• Genetic modification of oils – used for Soya, maize and oilseed rape• Use of fats – shortening, flavour, trapping air


Food IngredientsMilk, cheese and dairy products

• Milk and dairy products are good sources of calcium, protein, vitamin B12 and vitamins A and D

• To reduce fat content choose lower fat versions e.g. semi-skimmed and skimmed milk, low fat yogurts or fromage frais and lower fat cheese

• Soya milk is used by vegans

• Yogurt – milk is heated, cooled and mixed with a culture of bacteria. Kept at 40-45°C for 3-6 hours. Protein coagulates, the yogurt thickens

• Cheese – coagulating the protein in milk making curds and whey. The curd is pressed to make hard cheese like Cheddar

• Storage – should be kept in the fridge until the ‘use by date’

• UHT – can be kept at room temperature until opened


Food IngredientsEggs

• Nutritional value – good quality protein, fat, cholesterol, vitamin A, minerals: iron, phosphorus and calcium

Uses of eggs• Thickening – coagulation of the protein thickens sauces and custards

• Binding – egg coagulates and sticks the dry ingredients together as they cook e.g. bean burgers

• Coating – egg and breadcrumbs – the egg coagulates and provides a strong coating round fish

• Forms a foam – egg white can entrap air when its beaten – meringues

• Emulsifier – will stabilise – fat and sugar in a cake, oil and vinegar in mayonnaise

• Glaze – during baking – egg turns golden brown

• Salmonella – raw egg may contain this. Many companies use pasteurised egg. The Lion Quality mark shows that the hens have been vaccinated


Food IngredientsSugar

• Sugar provides energy. Sucrose is made from sugar cane or beetTypes of sugar• Granulated – used to sweeten drinks, adding to breakfast cereals• Caster – finer – cakes and biscuits• Icing – very fine - icings and sweets• Brown (soft) – gingerbreads and biscuits; Demerara – in coffeeFunctions: Sweetness, preservative, changes flavour, adds colour, bulking

agent, speeds up fermentation process e.g. yeast in bread, aids lightness in cakes

Sugar comes in many formsSucrose – also known as hydrolyzed starch, honey, glucose syrupMaltose – also golden syrup, lactose, brown sugarMaple syrup – glucose, fructose, fruit juicesInvert sugar – dextrose, treacle


Cooking ChoicesMethods of cooking and transfer of heat

• There is a variety of cooking methods used in food preparation• Large-scale manufacturers use the same processes but on a large scale.• Heat application used in the food industry –baking, steaming, roasting,

boiling/blanching/simmering, frying – shallow or deep fat, microwave cooking, grilling

• Heat application is used: to increase shelf life, to destroy enzymes and micro-organisms, to soften food to make it edible, to produce the desired consistency, to improve flavour, to increase the variety of food products

Methods of heat transferConduction – heat is conducted from molecule to molecule in solid and liquid

foodsConvection – heat travels around liquids and air by convection currents. Hot

air rises, so ovens are hotter at the topRadiation – direct rays of heat from the grill heat the foodMicrowaves cause the food molecules to vibrate – creates frictional heat


Food IngredientsRaising agents

• Bubbles of gas expand when heated and make a food mixture rise

• Three types of raising agent – air, steam, carbon dioxide gas

Air – introduced: sieving flour, beating (batters), whisking egg white (meringues), creaming (cakes), rubbing in (pastry, scones), rolling and folding pastry (flaky, puff)

Steam – water when heated turns to steam, this escapes pushing the mixture up (Yorkshire pudding, éclairs)

Carbon dioxide gas – this expands when heated and pushes up the mixtureBaking powder: made from acid sodium pyrophosphate, rice flour and

sodium bicarbonate. Reacts with the cake mixture > produces carbon dioxide gas

Bicarbonate of soda: same principle – used in gingerbread

Yeast: fungus which needs warmth, food and liquid to ferment producing carbon dioxide and alcohol. Most types of bread use yeast


Food IngredientsSetting ingredients

• Many food products are set to make them firm and attractive to eat• Gelling agents create a smooth, set texture and help to suspend other

foods in a jelly• Gelatine – made by boiling bones and tissues from animal carcasses. The

collagen in the connective tissue turns to gelatine when heated slowly in liquid. Sold in powder form and in sheets. Used for jellies and mousses.

• Pectin – found in the cells of fruit. Mixed with the right proportion of acid and sugar will form a gel. Used in jellies, jams and marmalades. When the jam is cool, the gelatine forms a network which sets and suspends the fruit, sugar and liquid

Agar agar – comes from a type of seaweed, used to set milk and liquids with low acidity (used by vegetarians and certain religious groups)

Carragheen – Irish moss. A by-product called carrageenan (E407) is used in ice-cream, jellies and frozen desserts as an emulsifier, thickener and gelling agent (used by vegetarians)

Gelozone and Vege Geli – setting agents


Food IngredientsAdditives

• The food industry uses specialist ingredients and may use additives in food products – these are added in small amounts

• ‘E’ – the letter ‘E’ sometimes appears before an additive number. This shows that the additive has been approved by the European Union

• Preservatives – protects against growth of micro-organisms (salt, sugar, vinegar, sulphur dioxide

• Colours – improve or change the appearance (caramel (E150)• Flavours and flavour enhancers – improve or replace those lost in the

cooking process (sugar, saccharin, aspartame, monosodium glutamate)• Emulsifiers and stabilisers – stops food separating (Lecithin)• Antioxidants – make foods last longer, stops fatty food going rancid

(vitamin C - ascorbic, vitamin E – tocopherol)• Other additives – raising agents, anti-caking agents, flour improvers,

thickening agents, nutrients, gelling agents• Are benefits and limitations for the food manufacturer and consumer


Food IngredientsComponents of foods

• Components - used in the food industry to save preparation time and costs

• Components help to produce a product that looks and tastes the same every time

• A component is used to describe an individual part of a product• Pre-manufactured standard components are ready prepared

ingredients or part of a product e.g. pizza bases, frozen pastry, pre-prepared pie fillings, ready grated cheese, cooked egg, fondant icing

Benefits of using these in the food industry• Cheaper than producing their own * May not have the equipment to

produce their own * Maintains consistency of the end product * Saves time by reducing some of the manufacturing process * Reduces costs *Keeps the assembly process as simple as possible

Limitations – Special storage conditions may be needed * Could be expensive * Supplier may be produce an inconsistent product * Reliant on supplier to deliver and to produce product in hygienic conditions


Food IngredientsPreservation part 1

Benefits of preserving food• Prevents micro-organisms (bacteria, moulds, yeasts) from multiplying• Enzymes – cause deterioration. These must be destroyed to improve

the keeping quality of the food• Increased shelf life of a product• Increases the range of foods available• Convenience – preserved food lasts longer which means fewer trips to

the shops• Allows the consumer to buy products out of season• Principle methods of preservation – dehydration, freezing, irradiation

and chemicalMethods of preservationDehydration – removal of water from a foodAFD, accelerated freeze-drying – food is frozen and driedCanning – food and liquid in a can, sealed then heated at high temperature


Food IngredientsPreservation part 2

MAP, modified atmosphere packaging – adds carbon dioxide, nitrogen or oxygen

Blast freezing – super quick freezing

Cook-frozen– food is cooked, fast frozen then stored below 0°CBlast chilling – food is chilled quickly by blasting cold air

Cook-chill – food cooked, fast chilled in 1 ½ hours, then stored at 0°-3°C

Vacuum packaging – air is removed from the product’s packaging

Irradiation – rays are passed from a radioactive beam through the food which reduces the number of micro-organisms

Other methods – Sodium nitrate (bacon manufacture), Salt (meat, fish), Sugar (fruits), Vinegar (onions, chutney), Alcohol (fruit), Smoke (fish, cheese, meats)


Food IngredientsSmart foods

• Smart or modern foods - respond to differences in temperature or light and change in some way. These come about by the invention of new or improved processes

Examples of smart or modern foods• Genetically modified foods• Modified starch• Meat alternatives e.g. textured vegetable protein (TVP), myco-protein• Anti-oxidants• Probiotic yogurts/drinks• Modified enzymes e.g. chymosin• Synthetic flavoursModified starch has been altered to perform additional functions e.g.pre-gelatinised starch – thickens instant desserts without heat * boiling

water can be added to gravy granules without it going lumpy * prevents ‘drip’ after a product has been defrosted * improves ‘mouth-feel’


Food productionSystems and control

• A system is a collection of elements, which work together to perform a task

• Systems enable products to be made: safely, hygienically, cost-effectively, efficiently, consistently, to an expected quality

• Systems are put in place in the food industry to control the production of food products

• A system has three main parts: input, process and output

• A fourth element in a system is called feedback

Elements of feedback

• Weight and mix control

• Trading standards regulations

• Environmental health

• Temperature control

• Thermostatic and sensor control

• Microbiological feedback

• Sensory analysis feedback• Shelf life and storage time

control

• Consumer feedback


Food productionHACCP (Hazard Analysis Critical Control Points)

• Food premises – where food is prepared, stored or sold• Hazard – anything that could harm the consumerSome examples of hazards:Physical e.g. glass in foodsMicrobiological e.g. bacteria in foodsChemical e.g. cleaning materials entering the productPotential hazards are identified using a system known as HACCP• Quality assurance – system set up before product is made – identifies

the procedures for making a safe, quality product• Quality control – steps in the making process to ensure the product

meets the standards specified. Any faulty products are removed• Food manufacturers and retailers need to make sure that all necessary

controls are put in place.Controls – storage & cooking temperatures, weight, size, shape of product,

pests, metal detection, machinery working correctly, food hygiene


Food productionJobs in the food industry

• General manager – in charge of everything• Product development technologist – specification details are correctly

produced and followed• Production manager – planning the time for production• Quality control manager – sets up quality assurance procedures• Health and safety manager – makes sure people are trained, follow

hygienic and safe procedures. Sets up HACCP system. Equipment safety• Product buyer – finds where to buy ingredients for products, costs and

availability• Food technologist – equipment needed, the science of the ingredients,

legal implications, responsible for production methods• Packaging technologist – types of packaging to use• Nutritionists – examine nutritional content• Production line supervisor – checks people are working efficiently and

the machinery is operating effectively


Food ProductionProduct analysis

• Product analysis is looking at all aspects of a product in detail• The product development team carry out product analysis on existing

products• Product analysis is carried out to:� Investigate how a product is made� Analyse the types and amounts of ingredients used� Gain ideas for new product development� Compare differences between brands� Check that a product matches its specification• Considerations when carrying out product analysis� Target market� Purpose of the product – how and when would the product be used?� Ingredients and additives – what are their functions?� Manufacturing processes used

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