1. The how’s & why’s
Industrial Products (Testing)
Why test
• everything is a product at some stage of the chain
• consumers of a product at one stage become suppliers to the next stage
• may be a number of processing steps under the category of Semi-Processed
Goods
• for all but the simplest of items, there will be multiple raw materials and
multiple semi-processed goods
Exercise 1.1
As a supplier of product, why is it necessary to test?
• to make sure your product is as you claim it is
• legal and sales problems otherwise
As a consumer of product, why is it necessary to test?
• it would be very unwise to assume that your supplier is perfect
Whose responsibility is it to test the product before it is further processed?
• The supplier
Exercise 1.2
“ingredients” for a loaf of white bread
wheat flour
milled from wheat
water
possibly purified, rather than directly from supply
yeast
supplied by biochemical manufact.
salt
from seawater, then purified
canola oil
pressed from seeds
sugar
extracted from sugar cane, then purified
soy flour
milled from soy beans
thiamine
?? chemical supplier
plastic bags & tags
plastic made from petrochemical, formed into sheets, labelled
• if the bread manufacturer needed to check the quality of all the ingredients,
we would be paying a lot more for our daily bread than we do
Exercise 1.3
Would you expect that the bread manufacturer does no testing of the
ingredients?
• no
• only do random checks beyond simple visual inspection
• rely on supplier’s quality system
1.2 What to test for
• the loaf of bread will need to be tested before it reaches the last consumer
• end-of-line testing is only part of the quality process
• quality control involves the checking of the partly finished product at
different stages
Exercise 1.4
mixing of dry ingredients, followed by addition of water
• are all the ingredients included in the right amounts
formation of dough
• is it at the right consistency
division of the dough into loaf portions
• are the tins filled up correctly
Exercise 1.4 cont’d
controlled temperature/humidity conditions for the rising of the dough
• are the settings for temperature & humidity levels correct
• is the bread rising properly
baking
• is the oven the right temperature
• is the conveyor belt moving at the right speed
• has the bread cooked properly
• does it taste right
bagging
• is the bread fitting into the bag properly
• is the tag going on correctly
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certain tests will be carried out on every item
for other tests, it must be done on selected samples
how often samples are taken and how much is taken
product testing is far more than just chemical or microbiological analysis
it is about product performance
consumers not all that interested in the exact % protein
they will care about how the bread tastes etc
Exercise 1.5
What do you think a loaf of bread should be tested for? And how often?
Every loaf
• metal fragments
• basic appearance
Some loaves every hour (or so)
• moisture content
• bagging
• taste
Once a shift
• bacterial contamination
Every so often
• other contamination
• chemical composition
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testing needs a comparison point to make a judgement against
a product specification or standard
describes the product in fine detail
gives upper and lower limits for its performance & composition
Exercise 1.6
Where would the detail for a product specification come from?
• internal – based on the design of the product
• customer – if it is a major contract, the customer will require certain
characteristics
• government – legal requirements, eg Food Standards Code
Who does the testing
• complex work done by outsourcing
CLASS EXERCISE 1.7
Let’s return to the bread manufacturer. Who will actually carry the testing
we have identified as being necessary?
• line operators
• simple checks, such as masses, temperatures, visual checks, taste
• in-house laboratory
• slightly more complex tests, eg moisture content
• commercial laboratory
• expensive/complex tests, eg microbiological
Sampling
• individual items can be sampled by random or stratified selection
• bulk materials are more difficult
• how much
• where from
• what with
• Australian Standards or in-house procedures
CLASS EXERCISE 1.8
What is the difference between the gross sample, laboratory sample and analytical
sample? How do you obtain one from the other?
• gross – the large quantity of material directly taken from the bulk
• laboratory – the material that comes into the lab for testing
• analytical – the portion that is actually analysed
• Gross to laboratory – mixing, division, homogenising
• Laboratory to analytical – division
How to test
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standard methods
saves development work
easier to prove to NATA inspectors that it is a valid method
validated in-house procedures
Sample preparation
• produce a sample that can be conveniently and accurately analysed
• remove some or all of the matrix from the analyte
• what type of sample preparation is required:
• the physical state of the sample – if is already a liquid, that makes life
much easier
• the nature of the analyte – is it inorganic or organic/molecular?
• the nature of the matrix – if it is relatively simple, then little preparation
may be required
CLASS EXERCISE 1.9
What types of sample preparation will be suitable for organic/molecular
analytes?
• extraction
• distillation
• filtration/centrifuging
What types of sample preparation will be suitable for inorganic analytes?
• acid digestion (wet ashing)
• dry ashing