Diet and Food Production

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Diet and Food Production
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Learning Outcomes

• Define the term balanced diet.
• Explain how consumption of an unbalanced diet can
  lead to malnutrition, with reference to obesity.

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Starter Question

• Nutrition come from the food we eat.
• What advantages are gained from eating well?
• E.g. better health
• Stronger immune system
• Ill less often
• Learn more effectively
• Make you stronger
• Make you more productive.

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Next question

• List the seven components of a balanced diet
• Carbohydrates
• Proteins
• Fats
• Vitamins
• Minerals
• Water
• fibre

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The macronutrients
Nutrient Elements present Use in body Good food sources
Carbohydrate Carbon, hydrogen, oxygen Source of energy Rice, potato, bread
Fats and oils Carbon, hydrogen, oxygen Source of energy Insulation Butter, milk, cheese, egg yolk
Protein Carbon, hydrogen, oxygen, nitrogen Growth and tissue repair Meat, fish, eggs, soya, milk
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Requirements of a balanced diet

• Sufficient energy for our needs
• Essential amino acids
• Essential fatty acids
• Micronutrients vitamins and minerals
• Water
• fibre

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Guidelines (17 year old girl)
Nutrient Mass/g per day
Carbohydrates 250
Fats 80
Proteins 60
Minerals 9.2
Fibre 12
Vitamins Traces
water variable
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Looking at the guidelines

• Are these the same for everyone?
• What factors will influence the energy
  requirements of different people?

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Energy intake

• It is recommended that energy intake come from
• 57 carbohydrates
• 30 fats
• 13 protein
• In an active person the amounts of each of these
  will increase

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Malnutrition

• Malnutrition is caused by eating an unbalanced
  diet
• This could mean eating much more than is needed
  or much less

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Eating too little

• A person who does not eat enough
• Lacks energy
• Shows signs of protein energy malnutrition
• Can have deficiencies that impair health
• Vitamin D rickets
• Vitamin C scurvy

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Eating too much

• Obesity is defined as when excessive fat
  deposition impairs health.
• Body mass index gt 30
• This is an indication that body weight is 20 or
  more above that recommended for your height.
• BMI mass in kg/(height in m)2

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Health risks associated with obesity

• Cancer
• Type 2 diabetes
• Coronary heart disease (CHD)

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Body Mass Index
BMI Category
lt18.5 Underweight
18.5 24.9 Acceptable
25 29.9 Overweight
30 34.9 Obese (class 1)
35 39.9 Obese (class 2)
gt40 Morbidly/severely obese (class 3)
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Prevalence of obesity

• Increasing in affluent countries
• People eat more than they need
• Take less exercise
• In the UK
• 25 men obese
• 20 women obese

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Learning Outcomes

• Discuss the possible links between diet and
  coronary heart disease (CHD).
• Discuss the possible effects of a high blood
  cholesterol level on the heart and circulatory
  system, with reference to high density
  lipoproteins (HDL) and low density lipoproteins
  (LDL).

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Coronary Heart Disease

• CHD is a degenerative condition
• It involves the build-up of fatty tissue in the
  walls of the arteries that supply the heart
  muscle.

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Atheroma
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CHD

• As a result of the build up
• Arteries become narrow
• Flow of blood decreases
• Supply of nutrients and oxygen to heart muscle is
  restricted
• The muscle does not release enough energy
• The heart becomes weak

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CHD

• Heart attack / myocardial infarction
• A blood clot in the coronary artery cuts off the
  blood supply to an area of heart muscle.
• Cardiac arrest
• Severe heart attack / heart stops
• Angina
• Pain when exercising
• Thrombosis
• Development of a blood clot

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Lipoproteins

• Lipoproteins
• Made in the liver
• Move cholesterol around the bloodstream
• As cholesterol is water soluble, it is coated
  with phospholipids and proteins so that they can
  travel in blood plasma

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Structure of a lipoprotein

• Phospholipids and protein coat
• Centre
• Cholesterol
• Triglycerides
• Other lipids

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Two types of lipoprotein

• There are two types of lipoprotein
• Low-density lipoprotein (LDL)
• Transports cholesterol to the tissues
• High-density lipoproteins (HDL)
• Remove cholesterol from tissues and return it to
  the liver
• HDLs have less lipid than LDL

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Cholesterol and CHD

• If there is a tear in the endothelial lining of
  coronary arteries
• LDLs enter the inner layer of the arteries
• The cholesterol and fat that they carry are
  oxidised and build up
• This forms an atheromatous plaque
• This enlarges the wall, giving the arteries a
  rough lining

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Atheromatous plaque
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HDLs good fat

• Appear to protect against CHD by removing
  cholesterol from the tissues, including the
  tissues in the walls of blood vessels.

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Its all about proportions

• Health professionals are now less concerned about
  the quantity of cholesterol in the body
• The focus is now on the proportions of HDLs and
  LDLs
• The more HDLs - the less chance of heart disease

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Fats in diet

• Diets rich in saturated fats tend to increase the
  cholesterol concentration of the blood due to a
  high LDL concentration
• Polyunsaturated fats in foods, e.g. fish oils
  help protect against heart disease and lower the
  concentration of cholesterol in the blood.

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Diet and CHD

• Antioxidants e.g. vitamin C and E
• Protective and reduce the risk of developing CHD
• Fresh fruit and vegetables are rich sources

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Question time!!

• A study followed 639 people with a family history
  of CHD over a period of 14 years. Some has an
  LDLHDL ratio of more that 8, while some had an
  LDLHDL ratio of less than 8. The graph shows
  the probability of survival of a person in each
  of these groups over the 14 years of study.

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The questions

• Explain why the survival probability is 100 at 0
  years
• Suggest why the graph is drawn so that it goes
  down in steps rather than in a smooth line.
• Describe the conclusions that can be drawn from
  these data.

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The answers

• This means that everyone was alive at the start
  of the study
• Data collected once a year
• Researchers did not know what happened in between
• If one or more people died in a year the graph
  goes down by a step
• Clear difference between results for people with
  high LDLHDL ratio and the lower LDLHDL ratio
• The lower ratio had the greater probability of
  survival

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Learning Outcomes

• Explain that humans depend on plants for food as
  they are the basis of all food chains.
• Outline how selective breeding is used to produce
  crop plants with high yields, disease resistance
  and pest resistance.
• Outline how selective breeding is used to produce
  domestic animals with high productivity.

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Food Chains

• Food chains represent feeding relationships
  between living organisms
• Plants are the basis of all food chains
• Autotroph
• Use an external energy source and simple
  inorganic molecules to make complex organic
  molecules
• Photosynthesis

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Food Chains

• All other organisms in the food chains are
  consumers
• Heterotroph
• Take in complex organic molecules as a source of
  energy
• Your diet depends on plants

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Food Production

• We can increase food production by making food
  chains more efficient
• Plants
• Improve growth rate of crops
• Increase yield
• Reduce losses due to pests and diseases
• Animals
• Increase rate of growth
• Increase productivity
• Increase resistance to disease

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Selective Breeding

• Artificial selection is the intentional breeding
  of certain traits
• Humans apply the selection pressure for the
  change in the population
• Stages
• Isolation
• Artificial selection
• inbreeding

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Selective Breeding in Plants

• Examples
• Tomatoes
• Bred with improved disease resistance
• Apples
• Varieties with improved texture and flavour
• Better quality
• Nutritional value
• flavour

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Selective breeding in Animals

• Increase in the yield of meat, milk and eggs
• Faster growing breeds
• Farmed salmon
• reduce time to market
• Production of lean (low fat) meat
• Egg laying chickens can lay up to 300 eggs per
  year

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Learning Outcome

• Describe how the use of fertilisers and
  pesticides with plants and the use of antibiotics
  with animals can increase food production

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Fertilisers

• Replace the minerals in the soil that are removed
  when crops are harvested.
• Help to increase growth rate and the overall size
  of the crops

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Fertilisers

• Artificial fertilisers contain
• Nitrogen (ammonia or nitrate ions)
• Make amino acids
• Magnesium ions
• Make chlorophyll
• Potassium ions
• Enzyme co-factors
• For Guard cells to open stomata
• Phosphate ions
• Make DNA, RNA and coenzymes

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Pesticides

• Pesticides are chemicals designed to kill pest
  species
• Herbicide
• Fungicide
• Insecticide
• Organic farmers use methods of crop rotation and
  biological control to control the number of pests

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Antibiotics

• Antibiotics can be used to
• Reduce the spread of disease among intensively
  farmed animals
• Add to animal feed to reduce the activity of gut
  bacteria (banned in EU)

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Learning Outcomes

• Describe the advantages and disadvantages of
  using microorganisms to make food for human
  consumption.
• Outline the methods that can be used to prevent
  food spoilage by microorganisms.

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Micro-organisms in food production

• Micro-organisms are used in food technology,
  where they act as production agents
• Turning ingredients into food
• Modifying food ingredients

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Micro-organisms in food production

• Bacteria
• Cheese
• Yoghurt
• Fungi
• Cheese
• Single celled protein / mycoprotein
• Yeast
• Brewing
• Winemaking
• Bread making

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Advantages of using micro-organisms

• Low fat foods free from saturated fat and
  cholesterol
• No ethical issues
• Quick growth, high yields, fast production

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Disadvantages of using micro-organisms

• Infection
• Contamination of fermenters by competitors
• Fungi, yeast and bacteria all use plant
  substrates
• Purification
• Palatability taste and texture

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Micro-organisms and Food Spoilage

• Food spoilage begins as soon as an item is
  picked, slaughtered or manufactured.
• Food poisoning is the presence of microbes or
  their toxins that cause illness or death

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Micro-organisms and food spoilage

• Visible growth (e.g. bread mould)
• External digestion process
• Clostridium botulinum produces botulin (toxin) -
  1µg is enough to kill
• Can cause infection e.g. Salmonella present in
  poultry
• Aspergillus produces carcinogenic toxins

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Preventing food spoilage

• In order to grow micro-organisms need
• Organic material
• Water
• Suitable temperature
• Oxygen
• Suitable pH
• Food preservation removes one or several of these
  conditions.

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Preventing spoilage

• Cooking
• Pasteurising
• Salting
• Pickling
• Freezing
• Irradiation

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Preventing contamination

• To prevent further contamination
• Canning
• Vacuum wrapping
• Plastic or paper packaging