The Final Analysis

Dairy processors may boost yield and product quality by adding in-line near infrared (NIR) analysis to the production process, Kimberly Pizinger, administrative manager of ProSpect Analytical Technology, says

The biggest impact on dairy processor's businesses comes from factors they cannot control, such as the cost of energy and raw materials. In-line NIR analysers may give processors a way to optimise what they can control, their processes, in order to achieve profit while ensuring quality and customer satisfaction. Processors can make the most of their raw material inputs, maximising product yield by minimising waste through automated real time formula adjustments.


Near infrared (NIR) light energy is closest in wavelength to visible light energy on the electromagnetic spectrum. Dairy constituents such as protein, fat, lactose or moisture absorb or reflect NIR energy at different levels. NIR transmission spectroscopy analysis measures the level of energy after it passes through a liquid or semi-solid product such as fluid milk or butter. NIR spectroscopy measures how light energy and matter interact. When light energy shines on or through a material, the amount reflected or absorbed depends on the composition of the material. An NIR spectrometer measures this light energy and supplies the data used to identify the nature and composition of the material.


NIR analysis can be a useful testing method in a variety of industries due to its speed, accuracy, safety and avoidance of extraneous chemicals. This is especially important for identifying low density constituents in low protein products such as WPC 35 or unconcentrated milk.

In-line NIR transmission analysis is a testing method that delivers data in one minute or less on a continuous basis. Operators and supervisors have real time information available, providing a continuous stream of data and the ability to facilitate automated process control. Trips to the lab are reduced or eliminated because a larger representative sample of the entire batch or run can be measured.


NIR reflectance spectroscopy analysis measures energy as it bounces off or if reflected by a solid product sample such as whey protein powder. NIR analysers for powder applications may be installed directly on the dryer, typically in the area just after the fluid bed in a position where the powder is free falling.

A hygienic sample cup is inserted into the process flow to capture a small amount of the product. The sample surface is doctored flat as it is retracted into the scan chamber. The NIR reflectance spectrometer captures the light energy signature from the sample before it is either returned to the process stream or is emptied into a container for transport to the laboratory for testing.


Once installed and calibrated to the factory's laboratory equipment by comparing the data collected with physical product samples, in-line NIR analysers incorporate networking capabilities designed to communicate directly with the factory's programmable logic controller (PLC). As the in-line NIR analyser detects deviations from the product set point, the analyser transmits constituent data so that automatic adjustments can be made during the liquid or powder production processes.

Cutting standard deviation in half is one reason adding in-line NIR analysis to the production process may make sense. In-line NIR automated process control increases productivity and product quality by minimising manual formula adjustments and operator errors, while reducing downtime and the need for re-work.

With in-line NIR analysis, more product is analysed, and there is no waste as with off-line sampling. Accurate predictions of multiple constituents are made in seconds and communicated in real time to maintain product consistency, reduce product giveaway and out-of-spec product.