CSS GSA — Paper 7, Part-I, Section IV (Food Science)

Concept of a Balanced Diet

• A balanced diet supplies all essential nutrients in appropriate proportions for growth, energy, and health maintenance. Core components:
  • Carbohydrates: primary energy source (~4 kcal/g)
  • Proteins: growth and tissue repair (~4 kcal/g); complete proteins (all essential amino acids) vs incomplete
  • Fats and Oils: concentrated energy source (~9 kcal/g), essential fatty acids, vitamin absorption (fat-soluble vitamins)
  • Vitamins:
    • Fat-soluble: A, D, E, K (stored in body fat, risk of toxicity with excess)
    • Water-soluble: B-complex, C (not stored significantly, need regular intake)
    • Key deficiency diseases: Vitamin A → night blindness; Vitamin C → scurvy; Vitamin D → rickets (children) / osteomalacia (adults); Vitamin B1 (Thiamine) → beriberi; Niacin (B3) → pellagra
  • Minerals: e.g., Calcium (bones/teeth), Iron (hemoglobin — deficiency causes anemia), Iodine (thyroid function — deficiency causes goiter), Zinc, Potassium
  • Fiber: indigestible plant material — aids digestion, gut health; soluble vs insoluble fiber

Quality of Food

• Bioavailability of nutrients: the proportion of a nutrient actually absorbed and used by the body (affected by food form, processing, presence of other compounds — e.g., Vitamin C enhances iron absorption)
• Sensory/quality attributes: Appearance (color, size), Texture (mouthfeel, consistency), Flavor (taste + aroma combined) — key parameters in food quality assessment
• Packed and frozen food quality: packaging protects against contamination/spoilage; freezing slows microbial growth and enzymatic activity, preserving nutrients/quality longer than many other methods
• Food Additives: substances added to enhance flavor, appearance, or shelf life (e.g., flavoring agents, colorants, emulsifiers)
• Preservatives: substances that inhibit microbial growth/spoilage (e.g., salt, sugar, sodium benzoate, nitrites)
• Antioxidants: compounds (natural — Vitamin C/E; synthetic — BHA, BHT) that prevent oxidative rancidity/spoilage of fats and extend shelf life

Food Deterioration and Its Control

• Causes of food deterioration: microbial growth (bacteria, molds, yeasts), enzymatic reactions (natural ripening/browning), oxidation (rancidity in fats), physical damage, improper temperature/moisture/storage conditions, pest infestation
• Adulteration: intentional addition of inferior, cheaper, or harmful substances to food to increase quantity/profit while reducing quality (e.g., water in milk, coloring agents in spices) — a food-safety and regulatory concern
• Food Preservation methods:
  • Thermal: pasteurization (mild heat, kills pathogens, e.g., milk), sterilization/canning (higher heat, longer shelf life)
  • Cold: refrigeration (slows spoilage), freezing (halts most microbial activity)
  • Dehydration/Drying: removes moisture microbes need to grow
  • Chemical: preservatives, salting, sugaring, pickling (acid/vinegar)
  • Irradiation: exposure to controlled radiation to kill pathogens/pests, extend shelf life without heat
  • Vacuum/modified atmosphere packaging: reduces oxygen exposure, slows oxidative and microbial spoilage

MCQ Traps

• Fat-soluble vitamins are A, D, E, K; all others (B-complex, C) are water-soluble — a frequently tested grouping
• Vitamin C deficiency causes scurvy; Vitamin D deficiency causes rickets/osteomalacia — don't swap these
• Fats provide ~9 kcal/g, roughly double carbohydrates/proteins (~4 kcal/g each)
• Pasteurization ≠ sterilization: pasteurization uses milder heat and does not eliminate all microorganisms/spores

Self-Test Questions