(1) Complete the statements (options: irradiation, dehydration, pasteurization, natural, chemical)
(a) Drying the food grains under the hot sun is called dehydration.
(b) Heating milk to a high temperature and cooling it quickly is called pasteurization.
(c) Salt is a natural type of food preservative.
(d) Vinegar is a chemical type of food preservative.
- (Note: School texts often group salt/sugar/oil/vinegar as “natural household” preservatives; if your key treats vinegar as natural, accept “natural” as an alternate.)
(2) Answer in your own words
(a) How is milk pasteurized?
Milk is heated to a specific temperature and then rapidly cooled to kill harmful microbes. It is heated to about 72 °C for seconds and cooled to 4 °C, then packed and kept cold. .
(b) Why should we not consume adulterated food materials?
Adulterants can be toxic (e.g., metanil yellow), cause allergies or long-term illness, reduce nutrition, and may carry microbes. They are illegal and unethical and can lead to food poisoning and chronic health problems.
(c) What precautions do your parents take to keep foodstuffs safe?
Buy fresh, check FSSAI/expiry dates, wash hands/utensils, keep foods covered, store hot foods hot and cold foods cold, refrigerate leftovers quickly, use airtight containers, keep raw and cooked foods separate, reheat thoroughly, and keep the kitchen clean and pest-free.
(d) How does food spoilage occur? Which factors spoil food?
Spoilage occurs when microbes grow or when chemical/enzymatic changes damage food. Factors: microorganisms (bacteria, yeasts, moulds), temperature (warmth), moisture, oxygen/light, enzymes, pests (insects/rodents), and poor hygiene/handling.
(e) Which methods of food preservation would you use?
Dehydration/sun-drying, salting, sugaring, pickling (vinegar/brine), oiling, refrigeration/freezing, pasteurization, canning, irradiation, vacuum sealing, and safe use of approved chemical preservatives (e.g., sodium benzoate) after checking regulations.
3) What shall we do?
(a) Vendors selling uncovered sweetmeats in open markets
Do not buy; choose shops that keep sweets covered and hygienic. Politely advise the vendor, and inform local health authorities if necessary.
(b) Pani-puri vendor serving with dirty hands
Avoid purchase; ask for hand-washing/gloves/tongs; prefer vendors who follow hygiene.
(c) We purchased a large quantity of fruits/vegetables
Sort and remove damaged pieces; wash and dry; refrigerate appropriately; follow FIFO (use older first); cut only before use; blanch-and-freeze extras; share/donate to avoid wastage.
(d) Protecting food from rats, cockroaches, wall-lizards
Keep kitchen clean and dry; store in airtight containers; fit mesh screens; cover bins; remove spills quickly; use traps or professional pest control.
4) Find the odd-man-out (with reason)
(a) salt, vinegar, citric acid, sodium benzoate ← (synthetic chemical preservative; others are natural household acids/salt)
(b) lakh(i) dal, brick dust, metanil yellow, turmeric powder ← (genuine food; others are common adulterants)
(c) banana, apple, guava, almond ← (nut/seed; others are fruits)
(d) storing, freezing, settling, drying ← (settling is a separation method, not a preservation method)
5) Complete the chart
| S.No. | Foodstuff | Adulterant |
| 1. | Turmeric powder (often also pulses/dal) | Metanil yellow |
| 2. | Black pepper | Papaya seeds |
| 3. | Tea leaves/powder | Iron filings |
| 4. | Honey | Sugar/glucose syrup |
6) Possible reasons (diagnose the problem)
(a) Qualitative wastage of food – Loss of taste/nutrition due to repeated reheating, exposure to air/light, improper storage, or long holding at unsafe temperatures.
(b) Cooked rice is underdone – Insufficient water, short cooking time/low flame, or using old/hard rice; lid opened too often.
(c) Wheat bought is moist – Grains not properly dried after harvest, absorbed moisture during storage/transport, or water added to increase weight.
(d) Yoghurt too sour/slightly bitter – Over-fermentation at warm temperature, old/too much starter, or contamination by unwanted microbes.
(e) Cut fruits have turned black – Enzymatic browning due to oxidation on exposure to air; prevent by adding lemon/acid, covering, and refrigerating.
7) Give reasons
1) Food remains safe at 5 °C.
Low temperature slows microbial growth and enzyme activity, reducing spoilage and keeping food safe longer.
(2) Nowadays, food is served buffet-style during large gatherings.
Buffets allow faster service, less handling by many people, and easier temperature control in covered chafing dishes, improving hygiene; guests choose portions, which reduces wastage and queues.