Food Science and Nutrition

Balanced Diet: Definition

A balanced diet is a diet that contains all the essential nutrients — carbohydrates, proteins, fats, vitamins, minerals, water and roughage (dietary fibre) — in the correct proportion and adequate quantity required by the body for proper growth, maintenance and functioning.

Needs of a Balanced Diet

1. Energy: Carbohydrates and fats supply the energy needed for daily activities, work and metabolism.
2. Growth and repair: Proteins are needed for the growth of new tissues and the repair of worn-out cells, especially in children, adolescents and pregnant women.
3. Body regulation: Vitamins and minerals are needed in small amounts to regulate body processes, build strong bones and teeth, and keep the immune system strong.
4. Hydration: Water is needed to transport nutrients, regulate body temperature and remove waste products.
5. Digestion: Roughage is needed to keep the digestive system healthy and prevent constipation.
6. Age, sex and activity: Needs vary with age, gender, occupation and physical activity — a growing child, a manual worker and a sedentary adult all need different quantities.

Importance of a Balanced Diet

1. Proper growth and development of the body, especially in children and adolescents.
2. Good health and immunity — protects against deficiency diseases such as scurvy, rickets, beriberi and anaemia, and reduces the risk of infections.
3. Energy and efficiency for work, study and physical activity.
4. Prevention of lifestyle diseases such as obesity, diabetes, hypertension and heart disease.
5. Healthy skin, hair, teeth and bones.
6. Sound mental health and better concentration.
7. Longer, productive life and improved quality of life.

Conclusion

A balanced diet is the foundation of good health. Eating a variety of foods from all food groups in the right proportion, along with clean water and regular exercise, keeps the body fit, prevents disease and supports overall well-being.

Needs and Importance of Balanced Diet

A balanced diet is a diet that contains all the essential nutrients—carbohydrates, proteins, fats, vitamins, minerals, water and roughage — in the right proportion and adequate quantity to meet the body's requirements for energy, growth, repair and maintenance of good health. No single food supplies all nutrients in the required amount, so a combination of different food groups (cereals, pulses, vegetables, fruits, milk, meat, fats and water) is necessary. Its needs and importance are described below.

1. Supply of energy Carbohydrates and fats in a balanced diet supply the calories needed for daily activities such as walking, working, cooking and other physical tasks. A deficiency causes weakness, fatigue and loss of working capacity.

2. Growth and development Proteins, minerals (calcium, phosphorus) and vitamins are needed for the growth of children, formation of bones and teeth, and increase in height and weight. A balanced diet in childhood and adolescence ensures proper physical and mental development.

3. Repair and maintenance of body tissues Proteins help in the repair of worn-out cells, healing of wounds and replacement of tissues. This keeps the body fit and slows down the ageing process.

4. Protection from diseases and infection Vitamins (A, B-complex, C, D, E, K) and minerals strengthen the immune system and prevent deficiency diseases such as night blindness, scurvy, beriberi, rickets and anaemia. A balanced diet thus keeps a person free from malnutrition and infection.

5. Proper functioning of body organs Minerals and water help in the proper functioning of the heart, muscles, nerves, kidneys and other organs. Water regulates body temperature, transports nutrients and removes waste products, while roughage (fibre) prevents constipation and keeps the digestive system healthy.

6. Maintenance of good health and body weight A balanced diet supplies the right amount of calories — neither too much nor too little — so it prevents both obesity and underweight. It keeps the body active, maintains a healthy weight and improves immunity and longevity.

7. Efficiency and productivity A person taking a balanced diet remains physically strong, mentally alert and free from fatigue. This increases his working capacity, concentration and productivity at work or study.

8. Prevention of malnutrition A balanced diet prevents protein-energy malnutrition (kwashiorkor and marasmus), obesity, diabetes, hypertension and other diet-related disorders. It is the cheapest and most effective means of preventing nutritional deficiency diseases.

Conclusion Thus, a balanced diet is essential for energy, growth, repair, protection from disease and the overall physical and mental well-being of a person. It should be planned according to age, sex, occupation and physiological condition (pregnancy, lactation, illness) so that the body gets all nutrients in correct proportion. In the hotel and catering industry, knowledge of a balanced diet is important for planning nutritious menus for guests of different age groups and health conditions.

Any two functions of minerals:

1. Building and repairing body tissues – calcium and phosphorus form and maintain bones and teeth.
2. Regulating body processes – minerals help muscle contraction, nerve impulse transmission, blood clotting, heart rhythm and fluid balance.

Causes of Food Poisoning

Food poisoning (food-borne illness) is an illness caused by eating contaminated food or water. It results from the presence of harmful bacteria, viruses, toxins or chemicals in food. The main causes are explained below:

1. Bacterial contamination This is the most common cause. Harmful bacteria such as Salmonella, Staphylococcus aureus, Clostridium botulinum, Escherichia coli and Clostridium perfringens enter food through poor hygiene, unclean hands, dirty utensils or infected food handlers. When such food is eaten, the bacteria or their toxins cause illness. For example, Salmonella is commonly found in raw poultry and eggs, while Staphylococcus aureus grows in cooked food left at room temperature.

2. Cross-contamination When raw and cooked foods are stored or prepared together, bacteria from raw food (especially raw meat) transfer to ready-to-eat food through chopping boards, knives, hands or containers. This transfer makes safe food unsafe and is a very frequent cause of food poisoning in kitchens.

3. Improper temperature control Bacteria multiply rapidly in the "danger zone" of 5 °C to 60 °C. If food is left in this range for more than two hours, kept warm but not hot enough, or cooled too slowly before refrigeration, bacterial growth increases greatly. Similarly, undercooked food does not reach a high enough internal temperature to kill bacteria.

4. Poor personal hygiene of food handlers Food handlers who do not wash their hands after using the toilet, who handle food while suffering from diarrhoea, vomiting, wounds or skin infections, or who cough and sneeze over food, transfer pathogens directly to food.

5. Contaminated water and raw materials Using unsafe drinking water for cooking, washing or ice-making, or purchasing spoiled, expired or already contaminated raw materials (meat, milk, fish, vegetables) introduces pathogens and toxins into the kitchen.

6. Cross-contamination from pests and animals Files, cockroaches, rats and pets carry bacteria on their bodies and deposit them on food, work surfaces and equipment. Their presence in a food area is a serious cause of contamination.

7. Chemical and toxic causes Poisoning may also result from chemicals rather than microbes — for example, pesticides sprayed on vegetables, cleaning agents stored near food, or naturally occurring toxins such as those in certain mushrooms, green potatoes or improperly preserved foods.

8. Poor storage and preservation Keeping food uncovered, storing it in dirty or damaged containers, or faulty refrigeration allows bacteria, moulds and toxins to develop. Mouldy food and foods kept beyond their expiry date are common sources.

Conclusion Food poisoning is mainly caused by bacterial contamination, cross-contamination, faulty temperature control, unhygienic food handlers, unsafe water, pests and chemical toxins. Most of these causes can be prevented by maintaining strict personal hygiene, safe storage, correct cooking temperatures and clean premises and equipment.

Vitamin D and animal fat

The sunshine vitamin is another name for vitamin D, because it is synthesised in the skin on exposure to sunlight. Lard is another name for animal fat (rendered pork fat).

(b) Food-borne pathogenic bacteria

Salmonella and E. coli are both food-borne pathogenic bacteria — harmful microorganisms that contaminate food and water and cause illness (food poisoning) when consumed. Salmonella is commonly linked to poultry, eggs and raw meat, while E. coli (especially E. coli O157:H7) is commonly linked to undercooked meat, raw vegetables and contaminated water.

Causes of Food Poisoning

Food poisoning is an illness caused by eating food that has been contaminated by harmful bacteria, toxins, chemicals or other agents. The main causes are as follows:

1. Bacterial contamination The most common cause. Bacteria such as Salmonella, Staphylococcus aureus, Clostridium botulinum, Escherichia coli and Clostridium perfringens multiply rapidly in food and produce toxins. This happens when food is kept at warm temperatures (the danger zone of 5°C–60°C) for too long, allowing bacteria to grow to dangerous levels.

2. Cross-contamination Harmful bacteria are transferred from one food to another. For example, using the same chopping board or knife for raw meat and then for cooked or ready-to-eat food, or handling raw food and then touching other food without washing hands.

3. Poor personal hygiene Food handlers who do not wash their hands after using the toilet, coughing, sneezing or handling waste can pass bacteria, viruses and parasites into food. Dirty nails, uncovered wounds and unclean uniforms also spread contamination.

4. Improper cooking and reheating Food that is not cooked to a safe internal temperature does not kill harmful bacteria. Similarly, leftovers that are not reheated thoroughly or are reheated more than once allow surviving bacteria to grow.

5. Improper storage and preservation Keeping food at the wrong temperature, leaving cooked food at room temperature for hours, or faulty refrigeration and freezing allow bacteria to multiply. Poor canning or preservation can also cause Clostridium botulinum poisoning.

6. Contaminated raw materials and water Using stale, expired or spoiled ingredients, unwashed fruits and vegetables, or water contaminated with sewage introduces pathogens and toxins into food.

7. Chemical and other contamination Pesticide residues, cleaning chemicals, poisonous mushrooms or other toxic plants, and metals from poor-quality utensils can also cause food poisoning.

8. Poor hygiene of premises and equipment Dirty kitchens, unclean utensils, pests such as flies, cockroaches and rats, and garbage kept near the preparation area all contaminate food.

Conclusion Most food poisoning is preventable. It can be controlled by maintaining personal hygiene, cooking food thoroughly, storing it at correct temperatures, avoiding cross-contamination and keeping the kitchen and equipment clean.

Provide energy and spare protein.

Preventive measures of food poisoning (5 marks)

Food poisoning results from eating food contaminated by harmful bacteria, toxins, or chemicals. It can be prevented at every stage — purchasing, storing, preparing, and serving — by following these measures:

1. Buy safe and fresh food: Purchase food from clean, reliable sources. Check the expiry date, look for freshness (colour, smell, texture), and avoid swollen or leaking cans, cracked eggs, and bruised fruits and vegetables.

2. Maintain personal hygiene: Food handlers must wash hands thoroughly with soap before handling food and after using the toilet, coughing, or touching waste. They should keep nails short, cover cuts with waterproof dressings, wear clean uniforms, and never handle food while suffering from diarrhoea, vomiting, or skin infections.

3. Store food at correct temperatures: Keep perishable foods in the refrigerator below 5°C and hot foods above 60°C, because bacteria multiply fastest between 5°C and 60°C (the danger zone). Cool leftovers quickly, refrigerate them within two hours, and reheat thoroughly before eating. Store raw and cooked foods separately to prevent cross-contamination.

4. Maintain kitchen and equipment hygiene: Clean and sanitise work surfaces, chopping boards, knives, and utensils after every use. Use separate boards for raw meat and ready-to-eat foods. Keep the kitchen free from pests, cover dustbins, and protect food from flies, rats, and dust.

5. Cook and serve food properly: Cook food thoroughly so that the centre reaches a safe temperature (about 75°C), especially meat, poultry, and eggs. Use safe drinking water, wash fruits and vegetables in clean water, and serve food immediately after cooking. Avoid reheating food repeatedly and never keep cooked food exposed for long hours.

Conclusion: Most food poisoning is preventable through cleanliness, correct cooking, and proper temperature control. Following these practices protects both customers and the reputation of the food service establishment.