NIR (Near Infra-Red) Use for Dairy Product

Currently we are planning to buy NIR for some finished product rapid analysis such as fat, protein analyzed. Can this NIR be used as a determination for the release of the finished product or only helps in the in line process? What about the reference method, because I can not find any reference method approve by AOAC related NIR? Does anyone have experience how to do NIR validation or use for finish product release? Many thanks

Greetings Ciegel,

You mentioned the release of the product, but in respect to what? Safety or quality? NIR doesn't fall much in the safety area but in the quality when you have specific limits on parameters for a let's say PDO product. Hence the method used will propably be provided by the company that sells you the equipment or even find it as a side instruction manual (however that doesn't mean that you can't play around if you are familiar with it). If it's a reknowned company you could even find youtube videos explaining or troubleshooting many methods/issues etc.

A special mention is that you can also use it to check for adulteration in your finished product, though it will often just be a poor quality product rather than an unsafe one.

The validation can be performed through some ways, but the easiest that come to mind is to either test a known product with set values in the parameters you want (a PDO one can be a safe choice) or take two identical samples and have one be analyzed in an external laboratory. In both ways you compare data and act accordingly if you see a far off deviation.

Hope it helps,

Regards!

What is NIR ??? Acronyms

Near infra-red ?

and PDO ???

Yes on the first and PDO = Protected Designation of Origin, like parmesan in Italy or feta in Greece.

Yes, NIR= Near Infrared 

in the USA, fluid milk.....   diary product is a pretty vague.

rapid methods for diary are used - almost exclusively for fat, protein, solids, etc..    Usually FTIR like a Foss.   I  believe most would be considered aoac approved or compliant I would ask the vendor.    the instrument would need to be calibrated to known samples and methods.   I cant remember who sells reference standards, but they are commercially available with a very short shelf life. 

Standardized predictions The MilkoScan FT+ is a high capacity, fully automated IDF and AOAC compliant FTIR (Fourier Transform InfraRed) spectrophotometer. The FTIR technology provides potential for analysis of virtually any component in milk. Kjeldahl protein Standardisation and equalizer patent The MilkoScan FT+ employs a patented standardisation principle that makes it possible to transfer calibrations between instruments, reducing the need and cost of calibration work considerably. FT-IR protein The purpose of standardization is to match the host (slave) spectra to the master spectra....

The answer is...it depends.  What parameters are you using to determine if the finished product can be released or not?

Like others have said, NIR is useful for determining chemical composition and sophisticated instruments like a FOSS FT-1 or FT-2 can measure almost anything provided you have a substantial calibration curve developed for it.

NIR by itself is not AOAC, but rather the reference methods for the reference samples you use to build the calibration curve on the instrument is AOAC.

For example, fat analysis with a substantial calibration curve can typically be within + 0.03%, or even better with enough calibration data.

**Most of these NIR instruments are not out of the box ready to use.  You have to use lots of references samples to refine the calibration data even if they have a calibration curve already.

I used to be the calibration coordinator for one of our manufacturing sites so have had a lot of experience in this area. Our company is using NIR analysis to release product (Cheese, Powders, MIlks) for the major chemical components, fat, moisture and protein and  Lactose, SNF on milks. However in order to do this, as others have noted, this needs a very robust calibration program., which includes the right samples, testing, calibration and validation.

For our milk products we use a FT120 and this is calibrated using reference standards provided by an external company. Our cheese and powder calibrations are built on years of analytical data of our product against reference test methods.  The equipment calibrations are checked regularly against samples of product tested using reference analytical methods. MIlk is probably one of the "easier" calibrations that can be made.

Most if not all milk companies use NIR to test their milks for both production and sale and there have been no issues in doing so. However the calibration requires regular "maintenance" seasonal variation in milk composition influences the test and calibration results. Calibrations are completed monthly and the data is added to the overall calibration to build a very robust calibration.

If you have the right data and can validate the calibrations on a regular basis to ensure it aligns with the reference test methods, there is no reason why you cannot use NIR analysis to test for chemical parameters and use that data to support the release of your product. It will just depend on what components you need to release on. The data you use is better if it is coming from you own products and own spectral data, You may get a base calibration from the supplier of the NIR equipment but it will need to be adjusted to fit your product matrix. It can be done, but to get a reliable calibration it can take many years of data collection and calibration.