General Science and Basic Food Science
What this domain tests
The General Science and Basic Food Science part of the WBPSC Food Sub-Inspector paper checks school-level physics, chemistry and biology applied to food. Expect questions on nutrient classes and energy values, vitamins, enzymes, food microbiology, preservation and simple food calculations.
Core rules and concepts
- Carbohydrate and protein supply about 4 kcal/g; fat supplies 9 kcal/g; alcohol supplies 7 kcal/g but is not a nutrient.
- Water-soluble vitamins are B-complex and C; fat-soluble vitamins are A, D, E and K.
- Enzymes are heat-sensitive proteins: amylase breaks starch, protease breaks protein and lipase breaks fat.
- Maillard browning needs a reducing sugar plus an amino group and heat; caramelisation needs sugar and heat only.
- Bacteria, yeasts and moulds cause spoilage. Clostridium botulinum is anaerobic and heat-resistant; Salmonella is a common foodborne pathogen; Staphylococcus aureus toxin is heat-stable.
- Preservation works by heat, cold, drying, acid, salt or sugar, irradiation or modified atmosphere.
Worked example
A 100 g snack has 20 g carbohydrate, 5 g protein and 10 g fat. Energy = (20 × 4) + (5 × 4) + (10 × 9) = 80 + 20 + 90 = 190 kcal. Fat contributes 90 kcal, nearly half the total, because fat is 9 kcal/g.
Traps that cost marks
Do not use 4 kcal/g for fat. Water activity is not the same as moisture content. Freezing stops bacterial growth but does not sterilise food. Boiling kills vegetative cells but does not destroy every toxin, such as staphylococcal enterotoxin. Do not confuse Maillard browning with caramelisation.