BCS Agriculture cadre Storage Engineering, Material Handling & Packaging: practice questions

Question 1 · medium

Why does modified atmosphere packaging of fresh produce depend on a controlled cold chain?

1. Films melt or lose their seals above about 10 °C, so the pack opens and the gas escapes
2. Cold kills all microbes in the pack, so any break in the cold chain lets them regrow from zero at once
3. Nitrogen condenses at room temperature
4. Respiration rises with temperature faster than film permeability, so a warmed pack can go anaerobic

Question 2 · medium

For MAP of non-respiring foods such as cheese or bakery products, the flush gas usually contains

1. Pure oxygen, which preserves the colour and freshness of all packaged foods
2. Ethylene to speed ripening
3. Carbon dioxide to inhibit microbes, with nitrogen as an inert filler
4. Phosphine to kill insects and mites that attack cheese and bread

Question 3 · easy

Which polymer is an excellent oxygen barrier when dry but loses much of its barrier at high humidity, so it is used between polyolefin layers?

1. Low-density polyethylene (LDPE)
2. Ethylene vinyl alcohol (EVOH)
3. Biaxially oriented polypropylene (BOPP)
4. High-density polyethylene (HDPE)

Question 4 · easy

Glassine paper is

1. Paper treated with sulfuric acid to make a wet-strength, grease-resistant parchment
2. Kraft paper coated with paraffin wax on both sides to make it water-resistant and glossy
3. Greaseproof paper that has been super-calendered to a dense, glossy, translucent sheet
4. A glass-fibre board

Question 5 · medium

Which material gives a good barrier to both water vapour and oxygen and is often used as a coating?

1. LDPE
2. Polyvinylidene chloride
3. Uncoated kraft paper
4. Expanded polystyrene

Question 6 · hard

Why does the logarithmic (falling driving force) shelf-life model predict a longer shelf life than the constant-rate model for the same data?

1. It assumes a thicker film
2. It ignores package area
3. It uses a lower storage temperature, at which the film's water-vapour permeability is several times smaller
4. As the product gains moisture its water activity rises, so the vapour-pressure difference and uptake fall

Question 7 · medium

Impulse heat sealers are particularly suited to polyethylene films because

1. The wire heats briefly and the seal cools under pressure, so soft PE does not stick or distort
2. They use ultrasonic vibration instead of heat, so PE is sealed without ever being melted
3. They seal only aluminium foil
4. They require no jaw pressure at all, so the soft PE film is never squeezed thin or distorted at the seal

Question 8 · medium

Induction sealing in packaging is used mainly to

1. Seal the longitudinal seam of a VFFS bag
2. Close jute sacks
3. Double-seam can ends
4. Seal a foil liner inside a bottle cap onto the container neck

Question 9 · easy

A VFFS machine makes 60 bags per minute, each 200 g, from film with a 0.25 m repeat length per bag. How much film does it use per hour?

1. 15 m
2. 900 m
3. 720 m
4. 54,000 m

Question 10 · easy

Which filler type relies on a constant bulk density to give accurate net weights?

1. Net-weigh filler
2. Cup filler
3. Multihead combination weigher
4. Check-weigher