Diet and Food Production

Balanced Diet: a diet which contains all the nutrients required for health in the appropriate proportions.

Balanced

  • Obesity is when a person is 20% or heavier than the recommended weight for their height. Obesity is caused through malnutrition, which is where a person’s diet is unbalanced. In this case of malnutrition, the person consumes too much energy and the excess is deposited as fat in the adipose tissues which can impair health. The conditions most commonly associated with obesity are cancer, cardiovascular disease, type 2 diabetes, gallstones, osteoarthritis and high blood pressure (hypertension).

HDL and LDL

  • High blood cholesterol is linked with coronary heart disease. Although it’s found in cell membranes, the skin and is used to make steroid sex hormones and bile, above 5.2mmol/dm3 is harmful. Cholesterol is insoluble but is carried by HDL’S and LDL’s. Lipoproteins are a combination of lipid, cholesterol and protein.
    •  HDL’s contain unsaturated fat and tend to carry cholesterol from the body tissues back to the liver where it’s used in cell metabolism to make bile or is broken down, meaning high levels of HDL’s are associated with reducing blood cholesterol levels. They reduce deposition of cholesterol in the artery walls (called atherosclerosis) and may help to remove the depositions already there.
    • LDL’s contain saturated fats. They tend to carry cholesterol to body tissue from the liver. The concentration of LDL’s in the blood increases when a diet contains too much saturated fat and cholesterol. High LDL levels result in deposition in the artery walls.
      • Saturated fats decrease the activity of LDL receptors in body tissue so as the concentration of blood LDL’s rises; less is removed resulting in higher LDL concentrations and more deposition. Polyunsaturated and monounsaturated fats increase the activity of LDL receptors so more is removed from the blood.
    • Coronary heart disease: a condition in which the coronary arteries narrow from an accumulation of plaque (atherosclerosis) and cause a decrease in blood flow.
  • Humans depend on plants for all food as they are the basis of all food chains. This is because humans eat both plants directly, and herbivores who eat plants.
  • Making food production more efficient:
    • Plants:
      • Improve growth rate, increase yield, reduce crop loss due to diseases/pests, easier harvest by standardising crop size, and improve response to fertilisers.
    • Animals:
      • Improve growth rate, increase productivity, and increase resistance to disease
    • Selective breeding:
      • Isolation → artificial selection → inbreeding/line breeding
      • A pair of animals displaying desirable characteristics is allowed to reproduce. The offspring are sorted and those with the best combinations of characteristics are allowed to reproduce. Over many generations this exaggerated the desired characteristic.
      • Selecting which animals can breed or which seeds to be sown is known as applying selection pressure.
    • Pesticides, fungicides and fertilisers increase plant yield as they are less likely to die from insects eating them or a fungal disease, and the fertilisers provide all the minerals the plant needs to grow so it can grow faster. Antibiotics can increase food production of animals as fewer animals die from disease so a higher yield is achieved.

bacteria2

  • Methods of preventing food spoilage;
    • Cooking – denatures enzymes and other proteins killing microorganisms
    • Pasteurising – heat then rapid cooling kills microorganisms
    • Drying/salting/coating in sugar all dehydrate microorganisms as water will leave their cells by osmosis
    • Smoking – smoke contains antibacterial chemicals and the food develops a hardened, dry outer surface.
    • Pickling – an acidic pH kills microorganisms by denaturing enzymes and other proteins.
    • Irradiation – ionising radiation disrupts the DNA structure of microorganisms so they are killed.
    • Cooling/freezing – although microorganisms aren’t killed, the activity of their enzymes is slowed so their metabolism/growth/reproduction is also slow.
  • Using microorganisms to make food (e.g. cheese/yoghurt/bread/alcohol/single cell protein (Quorn – a mycoprotein)
    • Advantages:
      • Can be much faster than animal/plant production
      • Production can be increased/decreased according to demand
      • No animal welfare issues
      • Good source of protein for vegetarians
      • Protein contains no animal fat or cholesterol
      • SCP could be combined with removal of waste products, as they grow on almost any organic substrate e.g. paper or whey
    • Disadvantages:
      • People might not want to eat fungi or food grown on waste
      • Need to isolate protein from the microorganisms in the fermenter
      • Protein needs purification so it’s not contaminated
      • Need to control infection – the microorganisms grow at the same temperatures as harmful pathogens
      • Palatability – the protein has a different taste/texture to meat
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