ICAR AICE-JRF/SRF Shelf-life Science & Food Stability: practice questions

1 · Kinetics of quality loss: zero- and first-order reactions · medium

For a first-order quality loss, a straight line is obtained by plotting

1. A against time
2. 1/A against time
3. A against ln time
4. ln A against time

2 · Packaging-limited shelf life and permeability calculations · easy

Taking 1 cm³ of oxygen at standard conditions as 1.43 mg, 8 cm³ of oxygen weighs about

1. 5.6 mg
2. 11.4 mg
3. 8.0 mg
4. 0.18 mg

3 · Accelerated shelf-life testing and its limits · medium

ASLT is generally unsuitable for

1. shelf-stable dry snacks limited by oxidation
2. canned foods limited by colour change
3. safety-limited chilled foods
4. milk powders limited by browning

4 · Accelerated shelf-life testing and its limits · medium

After ASLT predicts 12 months for a new cereal bar, good practice is to

1. start real-time storage in parallel and confirm
2. declare 18 months to be safe
3. stop all further testing
4. use the ASLT result as final without any further confirmation

5 · Microbial challenge tests and durability studies · medium

Challenge tests usually store inoculated packs

1. only at −18 °C
2. only at 37 °C for one day
3. at realistic and abusive temperatures
4. only at the lowest possible chill temperature

6 · Sensory end-points and survival analysis · medium

Triangle tests against a fresh control give a

1. measure of how many consumers would reject the product
2. conservative 'detectable difference' end-point
3. direct measurement of pathogen growth
4. value of the product's water activity

7 · Time-temperature integrators · medium

With TTIs on every case, a distributor can rotate stock by

1. alphabetical order of products in the warehouse system
2. largest case first
3. least shelf life remaining, first out
4. random selection

8 · Date marking: use-by, best-before and expiry · medium

Codex allows some foods to carry no date mark, such as

1. chilled ready meals
2. salt, sugar and vinegar
3. fresh minced meat
4. pasteurised milk

9 · Date marking: use-by, best-before and expiry · medium

A date mark of 'keep refrigerated at or below 5 °C; use within 3 days of opening' is an example of

1. an optional marketing claim
2. storage conditions accompanying a date
3. a sell-by date
4. a nutrition claim

10 · Shelf life of specific product groups · medium

Chocolate shelf life is commonly limited by

1. Listeria growth
2. fat bloom and sugar bloom
3. rapid moisture loss to zero
4. starch retrogradation