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Practice Exam and Answer Food Flavour Design
- Instelling
- Wageningen University (WUR)
Including question and answer of the exam preperation
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Voorbeeld 2 van de 10 pagina's
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Voorbeeld van de inhoud
Multiple Choice1. An oil supplier has received several customer complaints about the smell of canola oil. The oil
supplier therefore wants to implement analytical controls to assess the oil quality. Which
combination of methods would you recommend to assess the lipid oxidation level in bulk canola oil
(contains a-linolenic acid C18:3 w 3, and linoleic acid C18:2 w 6)?
Measure conjugated dienes and total aldehydes.
2. A company decided to test the antioxidant capacity of ascorbic acid and ascorbyl palmitate (=
ascorbic acid with a palmitic acid (16:0) esterified on it) in bulk oil and oil-in-water emulsions. To
evaluate the extent of lipid oxidation, they measured conjugated dienes and obtained the 2 graphs
below.
The black line correspond to the sample with ascorbic acid and the dotted line to the one with
ascorbyl palmitate
3. Which of the following molecules is not a secondary lipid oxidation product?
Peroxyl radical (primary lipid oxidation product)
Secondary lipid oxidation products (malondialdehyde, epoxide, nonanal)
4. A 10 wt.% O/W emulsion is tested for hydroperoxide concentration by spectrophotometry. To extract
the lipids, 2 mL hexane:isopropanol (3:1, v/v) is added to 0.5 mL emulsion. The concentration of
hydroperoxides measured in the sample with the help of a calibration curve is 50 µM. For simplicity
you may assume that the density of the emulsion and the oil are the same as that of water.
Which is the corresponding amount of hydroperoxides, expressed in mmol/kg oil?
1.55 mmol/kg oil
50 µM -> 0.05 mmol/kg
Oil -> 10% of 0.5 mL emulsion = 0.05 mL
Lipid extract -> 0.05 mL oil + 1.5 mL hexane = 1.55 mL
50
𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 ℎ𝑦𝑑𝑟𝑜𝑥𝑖𝑑𝑒 = = 1.55𝑚𝑚𝑜𝑙/𝑘𝑔
0.05 × 1.55
5. Yeast and acetic acid bacteria work together during the production of:
Vinegar
6. Lactic acid bacteria (LAB) can follow different pathways during glucose metabolism. What are the
end products formed during glucose metabolism by heterofermentative LAB under aerobic
conditions?
CO2, lactic acid and acetate
, 7. In which of the following processed drink is Maillard reaction not involved?
Smoothie
Maillard involves in: green tea (drying), sterilized milk (sterilize temperature), beer (roasting bean)
8. Which of the disaccharides below is a reducing sugar and can react in the Maillard reaction?
B
9. Which of the following structures obtained in a Maillard reaction is likely to originate at high pH from
glucose?
Structure A
10. Which reaction in the Maillard reaction is responsible for a drop of pH?
Retro-aldol reaction
11. Which of the following statements is not correct?
Polyphenol compounds interfere with the trigeminal system therefore, they are perceived as bitter
The sensors of temperature detection are located close to the taste cells
Heat and cold sensations can modify the perception of the other tastes
Capsaicin and menthol bind to thermoreceptors detecting high and low temperature, respectively
12. Select the statement that is correct
Upon swallowing, epiglottis and velum-tongue border are open and volatile compounds are
conveyed by exhalation to nasal cavity.
13. What is the correct definition of the odour activity value (OAV)?
OAV = dosage in food / sensory threshold.
14. How are flavoring substances characterized?
All the options are correct (sensory properties, legal status, physical and chemical properties)
15. Select the statement that is not correct.
When organizing sensory sessions...
...food products (solid, semi-solid, liquid) should be served at room temperature to rule out the
effect of temperature on sensory perception.
... if you want panelists (participants of a panel test) to focus on specific sensations (e.g., saltiness
and sweetness), it is best to use a red light to prevent cross-modal interactions during the
evaluation.
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