16 July 2015
Varying flavours of yoghurt with varying consistencies and varying ingredients can make for some varying appearances. Keeping the consumer happy with consistently appealing products can be challenging as, even if the ingredients are the same from batch the batch, they will never be truly identical and there will be some slight variation in appearance. Despite the variation in ingredients, a customer will still expect some conformity from product to product so colour analysis is a must to allow for quality to be controlled and colour matching to be achieved across batches.
Depending on the individual manufacturer’s production processes, samples of the yoghurt can be taken for analysis at varying points; the more frequent the measurements, the more accurate the quality control process can be. Practicality will determine how many stages can provide a sample for analysis but at the very least, before the product is packaged it should be made available for, as a minimum, one measurement.
The sample preparation and methodology involved will also dictate the regularity of sample testing so, to allow for a more efficient quality control process, the preparation for testing should be as easy and user friendly as is feasible to the manufacturer.
Some key points to think of when deciding on a method for your company
How thorough does your testing need to be?
For a thorough analysis of the product, data should represent the batch as a whole as far as is able. For the sake of time, a single measurement of a sample can be taken and recorded however, for a more detailed representation, an average of each sample can be taken. A higher degree of accurate data will take more time to quantify whereas a one-off measurement of a sample can be done quickly.
How much of the product is available for a single sample?
Do you have access to as much as is needed or is the supply for analysis limited? Strictly speaking, the more sample analysed, the more accurate the data collected.
How many samples of a batch can be taken?
To give a more accurate depiction of the product in its current state, multiple samples from across the entire batch would ideally be taken. The amount would depend on the size of the batch and the time available for batch testing.
What will you do with the results?
Is the purpose of the results to have referable data for each batch; data that can be used by manufacturers on different sites to ensure conformity of a product? Are different batches being produced at the same time and you want to ensure no contamination occurs?
How thick should the sample be?
The sample presented for measurement should be thick enough to give an opaque surface for measurement to receive more accurate data of the reflected colour. It must be remembered though, that due to the nature of the particles in liquid substances, some light may still pass through so the sample should also be backed with a white tile. This will ensure all light energy emitted by an instrument is utilised and not wasted.
For most methods concerning yoghurt’s, due to the thickness of the product, it is the reflected colour being analysed. This correlates with the human perception of the product as they will be looking at it in an opaque state.
For colour measurements of products such as this, as the reflected colour is being measured, a small, compact spectrophotometer is all that is required to give extremely accurate, quantifiable data to what the human eye sees.
An example of instrument and method that could be utilised by any manufacturer is as follows
A ColorFlex EZ Spectrophotometer would be ideal as it can measure the appearance of a product, giving accurate data relative to what the human eye perceives.
A ColorFlex EZ is capable of storing vast amounts of standard and sample data to accommodate any number of products that an individual manufacturer produces. The use of EasyMatch QC software can accommodate more data and can also provide more than enough detail for colour matching tasks.
Using a glass sample cup allows the sample to form a smooth, opaque surface for measurement. A half-filled sample cup would present enough sample to be analysed while reducing the risk of spillages. Only using enough of the sample to half fill a cup also means that less of the product is wasted and can allow for more samples of a batch to be taken for analysis.
How many measurements?
To obtain accurate data that best portrays the batch as a whole, taking average measurements would be a more precise method. Multiple samples, as many is necessary and feasible, can be taken from across a batch and the average data calculated to give data representing the batch.
Whatever the method chosen, it needs to be simple to follow for all operatives and be able to provide as much detail as needed for any number of samples that require analysis.
Content Written by Rachael Stothard