Fundamentals of Food Sampling and Analysis

 
Lecture 4.
Sampling methods, transportation and storage
for various environmental parameters.
 
By: Dinaol
 
4/28/2020
 
1
 
In this Lecture:
 
Food Sampling and analysis
 
4/28/2020
 
2
 
4.1.Food Sampling and analysis
 
 
4/28/2020
 
3
 
Key Words…..
 
Population
the total quantity from
which a sample is obtained
.
Sample
 a portion,  that is
representative of the
whole
 
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4
 
Lot
A definite quantity of some commodity
manufactured or produced under conditions, which
are presumed uniform.
Sampling
Procedure used to draw or constitute a
sample.
 
4/28/2020
 
5
 
Quality of Analysis Results
 
Quality of laboratory analysis results Relays on:
1.
Representatives of sample /collection, techniques/
2.
Sample handling /as per the product nature/
3.
Sample transportation
4.
Lab Sample preparation
5.
Methods
6.
Facility /equipment, reagent/
 
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6
 
 
Is there any risks associated with
sampling?
 
4/28/2020
 
7
 
Risks Associated with Sampling
 
There are two types of risks associated with
sampling:
1.
The consumer risk /probability of accepting a poor
quality population/
2.
FBO 
risk /the probability of rejecting an acceptable
product/.
 
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8
 
Basics for sample collection
 
Aim of sampling /proximate, Microbial,
contaminants/
Target population / homo or heterogeneity of
population/
 
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9
 
Sample Collection
 
 
What is Homogeneous Versus Heterogeneous
Populations?
 
 
 
 
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10
 
 
What are sampling techniques?
 
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11
 
Sampling Techniques/Methods
 
 
Basic sampling techniques:
Probability sampling,
Non-probability sampling,
 
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12
 
Types of sampling
 
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13
 
Probability Sampling
 
Probability sampling is used when a representative
sample is desired, and uses principles of statistical
sampling and probability i.e. elimination of human
bias.
It is a random selection approach that tends to give
each unit an equal chance of being selected.
 
4/28/2020
 
14
 
 
Simple random sampling
 
Number each frame unit from 1 to 
N
.
Use a random number table or a random number
generator to select 
n
 distinct numbers between 1 and
N
, inclusively.
Easier to perform for small populations
unpractical
 for large populations
 
4/28/2020
 
15
 
Systematic sampling
Convenient and relatively easy to
administer
Population elements are an ordered
sequence (at least, conceptually).
The first sample element is selected
randomly from the first 
k
 population
elements.
Thereafter, sample elements are selected
at a constant interval, 
k
, from the
ordered sequence frame.
 
k
 
=
 
N
 
n
 
W
h
e
r
e
n
 
=
 
s
a
m
p
l
e
 
s
i
z
e
N
 
=
 
p
o
p
u
l
a
t
i
o
n
 
s
i
z
e
K
=
 
s
i
z
e
 
o
f
 
s
e
l
e
c
t
i
o
n
i
n
t
e
r
v
a
l
 
4/28/2020
 
16
 
4/28/2020
 
17
 
Stratified sampling
involves dividing the population into overlapping
subgroups so that each subgroup is as homogenous
as possible.
Random samples are then taken from each subgroup.
The procedure provides a representative sample
because no part of the population is excluded and it
is less expensive than simple random sampling.
 
4/28/2020
 
18
 
Stratified sampling
 
 
4/28/2020
 
19
 
Cluster sampling
Similar to stratified sampling but the groups are
selected for their geographical location
 dividing the population into clusters or subgroups
so 
that cluster’s characteristics are as identical as
possible.
 Any heterogeneity occurs within each cluster.
The clusters are sampled randomly and may be either
totally inspected or sub sampled for analysis.
 
4/28/2020
 
20
 
4/28/2020
 
21
 
Composite sampling
is used to obtain samples from bagged products
such as 
flour, seeds, and larger items in bulk.
Two or more samples are combined to obtain one
sample for analysis that reduces differences between
samples.
 
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22
 
 
2. 
Non-probability Sampling????
 
4/28/2020
 
23
 
 
Non-probability sampling
Non-probability sampling is used when it is not
possible to collect a representative sample, or a
representative sample is not desired.
The sample collector uses judgement rather than
statistical considerations in the selection of the
sample.
The unusual or unexpected characteristics in a
population could be selected to be identified.
 
4/28/2020
 
24
 
Purposive/
 Judgment/
 Sampling
Sampling with “
a purpose
” in mind
Assessor recruits target population in need.
Example: when adulteration is an issue
Able to quickly reach targeted sample when sampling
for representativeness is not a major concern
Usually excludes unique or special cases
Often used in rapid assessments
 
4/28/2020
 
25
 
Quota sampling
 
Non-probability equivalent of stratified sampling
Assessor identifies stratums and their proportions
Convenience or purposive sampling used to recruit
samples
Select the first sample which aimed to fit  the need
regardless of what group they represent
Key is to select sample which match target
population.
 
4/28/2020
 
26
 
Convenience Sampling
Draw sample from population that are available and
easy to reach
This involves selecting the nearest and most
convenient people to participate in the research.
Used for pilot testing such as a random survey
Low cost and quick results
May match and compare convenience samples to
reduce bias.
 
4/28/2020
 
27
 
 
 
Sampling equipment status
 
4/28/2020
 
28
 
 Sampling equipment status
The devices or equipment's used to collect samples
should be sterilized before collecting samples
The sampling device should be clean, leak-proof.
The devices should have cover/cap
The cold food samples should be collected in cold
sampling devices
 
 
4/28/2020
 
29
 
 
 
Sampling amount and status
 
4/28/2020
 
30
 
 Sampling amount
Food sampling technique has it own procedure. The
major ones are the following.
1.
When taking the sample of packed food, the label should
not be damaged.
2.
If the amount of the packed food to be sampled is large, the
sample should be taken from different places and should be
mixed and collected in the sampling devices prepared for
this purpose.
 
4/28/2020
 
31
 
Sampling amount …
 
4. The amount of food sample depends on the amount
of the source food.
5. If the amount of the food (source food) is less than 5
kg or 5L the whole food can be taken as sample.
6. If the amount of the food is more than 5 kg or 5 Liter
the sample to be taken is as follows..
 
4/28/2020
 
32
 
Table : Minimum Number of Primary Samples to be
taken from a Lot
 
4/28/2020
 
33
 
Sampling Procedure and Minimum Amount to be Sampled from
lots of d/t crops
 
4/28/2020
 
34
 
 
Sending the Sample for Analysis
 
4/28/2020
 
35
 
Sending the Sample for Analysis
 
As much as possible do not remove pre-packed retail
samples from their packaging.
Seal the entire pack in a plastic bag after purchase,
and put the sample code on the outside of the bag.
Dispatch samples to the laboratory as soon as
possible after collection together with type of
analysis in need.
 
4/28/2020
 
36
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Discover the key methods and procedures for sampling, transportation, and storage of environmental parameters, focusing on food sampling and analysis. Explore the importance of representative samples, quality analysis results, and risks associated with sampling. Learn about homogeneous vs. heterogeneous populations, sampling techniques, and the basics of sample collection. Enhance your understanding of ensuring the quality of laboratory analysis results through proper techniques and practices.


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  1. Lecture 4. Sampling methods, transportation and storage for various environmental parameters. By: Dinaol 4/28/2020 1

  2. In this Lecture: Food Sampling and analysis 4/28/2020 2

  3. 4.1.Food Sampling and analysis 4/28/2020 3

  4. Key Words.. Population the total quantity from which a sample is obtained . Sample a portion, representative whole that of is the 4/28/2020 4

  5. Lot A manufactured or produced under conditions, which are presumed uniform. Sampling Procedure used to draw or constitute a sample. definite quantity of some commodity 4/28/2020 5

  6. Quality of Analysis Results Quality of laboratory analysis results Relays on: 1. Representatives of sample /collection, techniques/ 2. Sample handling /as per the product nature/ 3. Sample transportation 4. Lab Sample preparation 5. Methods 6. Facility /equipment, reagent/ 4/28/2020 6

  7. Is there any risks associated with sampling? 4/28/2020 7

  8. Risks Associated with Sampling There are two types of risks associated with sampling: 1. The consumer risk /probability of accepting a poor quality population/ 2. FBO risk /the probability of rejecting an acceptable product/. 4/28/2020 8

  9. Basics for sample collection Aim of contaminants/ Target population / homo or heterogeneity of population/ sampling /proximate, Microbial, 4/28/2020 9

  10. Sample Collection What is Homogeneous Versus Heterogeneous Populations? 4/28/2020 10

  11. What are sampling techniques? 4/28/2020 11

  12. Sampling Techniques/Methods Basic sampling techniques: Probability sampling, Non-probability sampling, 4/28/2020 12

  13. Types of sampling 4/28/2020 13

  14. Probability Sampling Probability sampling is used when a representative sample is desired, and uses principles of statistical sampling and probability i.e. elimination of human bias. It is a random selection approach that tends to give each unit an equal chance of being selected. 4/28/2020 14

  15. Simple random sampling Number each frame unit from 1 to N. Use a random number table or a random number generator to select n distinct numbers between 1 and N, inclusively. Easier to perform for small populations unpractical for large populations 4/28/2020 15

  16. Systematic sampling Convenient and relatively easy to administer Population elements are an ordered sequence (at least, conceptually). The first sample element is selected randomly from the first k population elements. Thereafter, sample elements are selected at a constant interval, k, from the ordered sequence frame. k = N n Where n = sample size N = population size K= size of selection interval 4/28/2020 16

  17. 4/28/2020 17

  18. Stratified sampling involves dividing the population into overlapping subgroups so that each subgroup is as homogenous as possible. Random samples are then taken from each subgroup. The procedure provides a representative sample because no part of the population is excluded and it is less expensive than simple random sampling. 4/28/2020 18

  19. Stratified sampling 4/28/2020 19

  20. Cluster sampling Similar to stratified sampling but the groups are selected for their geographical location dividing the population into clusters or subgroups so that cluster s characteristics are as identical as possible. Any heterogeneity occurs within each cluster. The clusters are sampled randomly and may be either totally inspected or sub sampled for analysis. 4/28/2020 20

  21. 4/28/2020 21

  22. Composite sampling is used to obtain samples from bagged products such as flour, seeds, and larger items in bulk. Two or more samples are combined to obtain one sample for analysis that reduces differences between samples. 4/28/2020 22

  23. 2. Non-probability Sampling???? 4/28/2020 23

  24. Non-probability sampling Non-probability sampling is used when it is not possible to collect a representative sample, or a representative sample is not desired. The sample collector uses judgement rather than statistical considerations in the selection of the sample. The unusual or unexpected characteristics in a population could be selected to be identified. 4/28/2020 24

  25. Purposive/ Judgment/ Sampling Sampling with a purpose in mind Assessor recruits target population in need. Example: when adulteration is an issue Able to quickly reach targeted sample when sampling for representativeness is not a major concern Usually excludes unique or special cases Often used in rapid assessments 4/28/2020 25

  26. Quota sampling Non-probability equivalent of stratified sampling Assessor identifies stratums and their proportions Convenience or purposive sampling used to recruit samples Select the first sample which aimed to fit the need regardless of what group they represent Key is to select sample which match target population. 4/28/2020 26

  27. Convenience Sampling Draw sample from population that are available and easy to reach This involves selecting the nearest and most convenient people to participate in the research. Used for pilot testing such as a random survey Low cost and quick results May match and compare convenience samples to reduce bias. 4/28/2020 27

  28. Sampling equipment status 4/28/2020 28

  29. Sampling equipment status The devices or equipment's used to collect samples should be sterilized before collecting samples The sampling device should be clean, leak-proof. The devices should have cover/cap The cold food samples should be collected in cold sampling devices 4/28/2020 29

  30. Sampling amount and status 4/28/2020 30

  31. Sampling amount Food sampling technique has it own procedure. The major ones are the following. 1. When taking the sample of packed food, the label should not be damaged. 2. If the amount of the packed food to be sampled is large, the sample should be taken from different places and should be mixed and collected in the sampling devices prepared for this purpose. 4/28/2020 31

  32. Sampling amount 4. The amount of food sample depends on the amount of the source food. 5. If the amount of the food (source food) is less than 5 kg or 5L the whole food can be taken as sample. 6. If the amount of the food is more than 5 kg or 5 Liter the sample to be taken is as follows.. 4/28/2020 32

  33. Table : Minimum Number of Primary Samples to be taken from a Lot Weight/volume of lot (in kg or l) Minimum Number of Primary Samples to be taken from a Lot (kg or l) <50 3 50-500 5 500- 1000 10 1000 - 3000 20 Number of cans, cartons, containers in the lot Minimum Number of Primary Samples to be taken from a Lot (cans or cartons etc) 1-25 1 26-100 5 > 100 10 4/28/2020 33

  34. Sampling Procedure and Minimum Amount to be Sampled from lots of d/t crops Crop Type Sampling Procedure Example Minimum Quantity 5 kg Root, tuber and bulb vegetables Take samples from all areasof the crop. Remove asmuch adhering soil aspossible from samples butdo not wash. Remove as much soil as possible from crops such as celery, but do not wash. Beet ,onions, potatoes, sweet potatoes, turnips Leafy, stem, Fruits and legume vegetables lettuce, spinach, Cucumber, Peppers,tomatoes, Beans, peas (with pods) Maize, wheat 5 kg Cereal Grains Cut not less than ten smallareas (approximately 0.1 m2)chosen randomly from allareas of the crop. Remove grain fromthe straw. 2 kg 4/28/2020 34

  35. Sending the Sample for Analysis 4/28/2020 35

  36. Sending the Sample for Analysis As much as possible do not remove pre-packed retail samples from their packaging. Seal the entire pack in a plastic bag after purchase, and put the sample code on the outside of the bag. Dispatch samples to the laboratory as soon as possible after collection together with type of analysis in need. 4/28/2020 36

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