Lecture 2: Sampling and data Analysis

Question 1

What is the role of CFIA in controlling food saftey?

Answer 1

The role of the CFIA is to safeguard food animals, plants to protect us, others, the enviorment and the economy.

Ensure what we have on our plate is safe and high quality, work to prevent the spread of invasive plants, pests, and animal diseases as safe food starts there. All based on science, while combating the struggles of today like climate change.

SAFEGUARD WITH SCIENCE

Question 2

What are some services the CFIA does?

Answer 2

food recalls, exporting food plants or animals, food label requirments, food saftey, food licenses, inspection and enforcment, plant and animal health, etc.

Question 3

Describe the different food sampling based on the nature of the physical, chemical and microbiological risk.

Answer 3

Physical (extraneous materials, bone fragments):

• finished food
• food in line

Chemical (Allergens, drug residues, pesticide, toxins):

• enviorment sample
• finished food
• food in line

Microbiological risk (pathogens, microorganisms): be aware of organsim looking for because not linear, when taking the sample it should be in the same conidtion as it was in the shop so that it does not influence the growth or death of the bacteria.

• enivorment sampled (where food is prepared)
• finished food
• food in line

Question 4

What is the purpose of representative food sampling and how is it done?

Answer 4

The purpose of this is to obtain a representitive unit to estimate the whole thing. In order to do so a sampling plan must be devoloped that provides international methods so there are no disputes. The sampling method should meet the following requirements:

• specifiy procedures of sample collection/preperation
• specify size and number of samples
• specifiy statistical criteria to either be accepted or rejected

Question 5

What are the 4 steps of prepapring laboratory samples?

Answer 5

1. Make the samples homogenous: different depending on properties of food, many ways to achieve like enzyamatic methods, mechanical devices or chemically
2. reduce sample size: so that is more managable while still representing the population from which it came
3. prevent changes in the sample: ensure that the sample does not undergo changes that are significant from collection until analysis
4. Label sample for identification: description of sample, who took the sample, when and where, what method was used

Question 6

What are the 4 types of changes to avoid between the time the sample was collected until the time of analysis

Answer 6

1. presence of enzymes: enzymes like proteases, lipases, cellulases can cause changes in the properties of food
2. chemical alteration: any exposre to light, high temp, oxygen, pro-oxidants can increase the rate of reactions like oxidation rxns
3. microbial growth and contamination: can occur naturally in food, so important to check and ensure that is not happening
4. physical changes: examples include water being lost, gained, melting of fat or ice

Question 7

Whats the difference between accuracy and precision?

Answer 7

A: degree of closeness to true value

P: degree of repeating same value

Question 8

Define Linearity

Answer 8

directly proportional to an activity

Question 9

Define sensitivity

Answer 9

limits of dectection/determination

Question 10

List the statistical analyses use

Answer 10

• standard deviation: measures dispersion relative to mean
• coefficient of varation:SD/mean
• confidence interval : range of values that is likely to include a population with a certain degree of confidence

Question 11

What is the use of a standard curve

Answer 11

Standard Curve: used to determine certain properties of an unknown product using known properties