State the principles involved in the following methods of food preservation: (a) (i) Salting (ii) Refrigeration (iii) Drying (iv) Smoking (v) Chemicals. (b)...

(a) Principles of food preservation methods

• (i) Salting: salt draws water out of the food and out of any microorganisms by osmosis, creating a dry, high-salt condition in which bacteria and fungi cannot grow or multiply.
• (ii) Refrigeration: low temperature slows down (inactivates) the enzymes and the growth and multiplication of the microorganisms that cause food to spoil, so decay is delayed.
• (iii) Drying: removal of water (moisture) from the food deprives spoilage microorganisms of the water they need to grow and reproduce, and slows enzyme activity, so the food does not decay.
• (iv) Smoking: heat and smoke dry the food and coat it with chemicals (such as creosote and other antiseptic substances in wood smoke) that kill or check the growth of microorganisms.
• (v) Chemicals (chemical preservatives): added chemicals such as sodium benzoate, sugar or vinegar kill microorganisms or create conditions (acidity, high sugar concentration) in which they cannot grow.

(b) Four problems caused by human overpopulation

• Shortage of food, leading to malnutrition and hunger.
• Shortage of housing / overcrowding and growth of slums.
• Unemployment and poverty.
• Pressure on and inadequacy of social amenities (schools, hospitals, water, roads).
• Increased pollution and destruction of the environment.
• Increased spread of diseases and rise in crime rate.

(c) Three ways the Government may increase food production

• Providing loans, subsidies and farm inputs (improved seeds, fertilisers, pesticides) to farmers at cheaper rates.
• Encouraging mechanised farming and providing modern farm machinery and irrigation facilities so that larger areas can be cultivated all year round.
• Establishing agricultural research institutes to produce improved (high-yielding, disease-resistant) crop varieties and livestock breeds, and training farmers through extension services.
• Building good storage and processing facilities and good roads to reduce post-harvest losses and encourage farmers.