Butter is a dairy product made by churning milk or cream to separate the butterfat from the buttermilk. It is one segment of the dairy market that includes milk and milk-based products.
Domestic production of milk was estimated at 215 million pounds in the United States with about 17% of this used to make butter. According to standard regulations, the only fat butter can contain is butterfat as an emulsion of fat and water. It contains 80% to 90% butterfat, up to 16% water, milk proteins, and can contain salt as well.
Butter is typically light yellow and has a variety of uses, such as a spread on bread products, a condiment on cooked vegetables, a dipping sauce for bread and seafood, and cooking uses like pan frying and baking.

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Butter consumption is high in many parts of the world and high market growth is anticipated in coming years for numerous reasons. Consumer consumption of fast, processed, and convenience foods is increasing and butter is often a key ingredient in such foods. Butter sales are driven by its nutritional value and the diversity of applications across the food industry.
Technological advances in the dairy industry and butter manufacturing have contributed to increased production and market growth. All segments of the dairy industry (including butter) tend to be highly localized due to the perishable nature of the products. Advances have increased the long-distance export of butter, improved flavor and quality, and increased shelf-life of the final product.
Innovations for obtaining more milk from dairy animals, such as in feed formulation and advances in feed quality control and testing, have also contributed to increased production of milk and butter. One statistic from the U.S Department of Agriculture estimates that over a recent ten-year span, milk production increased by 13.4% while the number of dairy cows only increased by 0.8%.
Quality control testing to ensure the quality and safety of dairy products is of paramount importance, especially because of their perishability. There is a large amount of variability in raw materials and processing techniques like drying, heating, cooling, freezing, and pasteurizing require rapid and cost-effective methods to ensure quality.
Consumer awareness of quality assurance is a major factor in the purchase and consumption of dairy products. The implications of poor product quality in today’s social media environment as well as the financial consequences of a product recall can be devastating to a company’s bottom line.
Traditional testing methods for butter analysis often include time-consuming and expensive wet chemistry methods. They are labor-intensive, require the use of toxic chemicals and solvents, and are ill-suited for real-time on-line analysis. Most testing methods are also only capable of measuring a single chemical or physical parameter of interest per test.
An excellent example of this is the reference method to determine Solid Fat Content (SFC), a critical parameter in butterfat and other dairy products. The standard method for measuring SFC is Nuclear Magnetic Resonance (NMR), which requires over sixteen hours of sample preparation. It is expensive and impractical for real-time analysis.
Adulteration is a major issue in many food and beverage products including dairy and butter. Different methods of adulteration are always emerging and there is a need for the evolution of testing methods to detect adulteration.
NIR spectroscopy offers a fast and cost-effective alternative to traditional testing methods for both quality control analysis and adulteration detection in butter. Little to no sample preparation is required. Although the use of NIR spectroscopy does require the creation of chemometric models that correlate parameters of interest to NIR spectra, once models are created multiple parameters can be determined from a single measurement.
Advances in hardware and software in NIR spectroscopy have facilitated the use of it as a real-time quality control method during the manufacturing of butter. In the sections below, an overview of the manufacturing of butter and the use of NIR spectroscopy for quality control analysis is examined. Adulteration detection is also discussed as well as recent advances in the use of NIR spectroscopy in butter quality control.
Butter Manufacturing
Butter manufacturing is a multi-step process that is usually done continuously today, although smaller manufacturers may use batch processing. Cream is procured and prepared. It can be provided directly by the milk dairy or separated from whole milk by the butter manufacturer.
Cream at a pH above 6.6 is preferable to avoid rancidity or oxidation before cooling. Fat content can be adjusted after cooling and then the cream is pasteurized at a minimum temperature of 95°C to destroy enzymes and microorganisms. If fermentation is desired, mixed cultures are added to the cooled cream at this stage.
Cream is moved to an aging tank and subjected to controlled cooling, which gives the fat the required crystalline structure. Different factors affect the final consistency and hardness of the butter, such as oxidative parameters, unsaturated fatty acid content, and the proportion of the three separate fat forms: free butterfat, butterfat crystals, and undamaged fat globules.
After aging, cream is pumped through a heat exchanger to a churn at a temperature around 55°F. An excessively high temperature results in quickly made butter but substantial fat loss. An excessively low temperature results in long churning and butter that is too hard. Churning agitation breaks down fat globules, causing the fat to coagulate into butter grains and decrease the fat content of the buttermilk liquid.
Buttermilk is drained off from the butter grains and additional washing of the grains can occur to remove residual buttermilk and milk solids. Butter grains are pressed together and any residual water is drained off. If salt is added, it is added after grain pressing and worked together to create the final product.
Proper working in the final stage as well as possible addition of water to standardize the moisture content is essential to obtain maximum yield and the desired aroma, taste, shelf-life, appearance, and color. NIR spectroscopy provides a fast and non-invasive method for monitoring parameters of interest during the multi-step butter manufacturing process.

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Fat & Moisture
Fat and moisture are the two most important quality parameters in butter. They are important in the manufacturing process, final product quality control analysis, and for adulteration detection. Both fat and moisture are proven chemical parameters that can be measured using NIR spectroscopy. NIR spectroscopy is especially well-suited for moisture measurements because the water is highly absorbing in the NIR, making even small changes in moisture content easily detectable.
NIR spectroscopy can be used at all stages of the butter manufacturing process to determine fat and moisture content. It can be used to measure parameters in milk or cream before manufacturing, during the manufacturing process as a real-time quality analysis tool, and as a quality control check for the finished product. Numerous studies have proven the feasibility of fat and moisture analysis of butter using NIR spectroscopy as a replacement for traditional time-consuming and expensive methods.
Solid Fat Content
Solid Fat Content (SFC) is a measure of the solid fraction of crystallized fat in terms of weight percentage. It is a good indicator of the functional characteristics of milk fat. Cream is a water and oil emulsion and during butter churning, fat globule membranes can rupture which causes the fat to agglomerate.
Because the optimum crystallization pattern in the fat is a function of temperature, direct knowledge of the SFC of cream can help the butter maker determine the proper conditions. Functional characteristics of butter and other cream-based products, such as texture and spreadability, are largely dependent on SFC.
Currently, the approved standard method by the American Oil Chemists’ Society (AOCS) for determining SFC in butter is Nuclear Magnetic Resonance (NMR) spectroscopy. NMR requires a sixteen-hour delay period for tempering the fat at 0°C before measurement and subsequent analysis from 0°C to 35°C in 5°C increments. While effective, NMR is impractical for real-time measurements as well as expensive and labor-intensive.

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NIR spectroscopy has been examined as a method for determining SFC in butter. A study was conducted using New Zealand butter samples. Standard procedures were followed that included the collection of NIR spectra, reference method determination of SFC, and chemometric modeling creation which correlates the NIR spectra to the SFC in the butter samples.
Separate models were constructed for each 5°C temperature increment and modeling statistics showed high correlation between prediction results from the NIR spectra and reference values. While more work would likely be necessary to implement this application in a real-time setting, the feasibility of the measurement was proven.
The benefits of replacing NMR with NIR spectroscopy to determine SFC during the butter manufacturing process cannot be understated. Replacing an expensive and time-consuming method with real-time results from the collection of a single NIR spectrum not only greatly reduces cost and labor, it also optimizes both yield of the final product and functional characteristics of the butter.
Adulteration Detection
Food authenticity and detection of adulteration have become a priority for both food producers and consumers. Adulteration results in reduced profits, bad publicity, and in some cases, a health risk to the public. Dairy products are a target for adulteration and one potential adulterant in butter is tallow. Tallow is an animal fat material that can be used to make candles and soap. It causes increased serum cholesterol and triglycerides levels when consumed and is an unsuitable addition to butter at any concentration.
Visual and sensory examination are often insufficient for determining the presence of adulterants in butter. Wet chemistry methods are time-consuming and expensive. NIR spectroscopy offers a fast and non-invasive method for determining adulteration in butter. One study examined the feasibility of determining the presence and concentration of tallow adulterant in butter samples.
Butter samples were prepared by adding varying concentrations of tallow up to 20% concentration. NIR spectra were collected and the reference values for tallow were used to create chemometric models. Two types of models were created: one to determine the presence of tallow as a qualitative measurement and the other to determine the concentration of tallow in the butter.
Validation using independent samples proved the feasibility of the measurement. Tallow concentration can be predicted from the NIR spectra with an error of less than 2%. Future work could include different types of butter samples to create a universal model for detecting tallow concentration in all types of butter.
Process Analytical Technology (PAT)
Process Analytical Technology (PAT) was first introduced by the FDA for the pharmaceutical industry but has proven to be effective as a modeling and control strategy for the food industry. Many steps of the butter manufacturing process benefit from using the principles of PAT to ensure quality.
Inherent advantages of implementing PAT into butter manufacturing analysis include controlled and optimized utilization of raw materials, reduction in variation of the final product, waste reduction, minimization of process cycle time, and the replacement of slow, costly, and ineffective laboratory testing methods with newer and more reliable sensor technologies, such as NIR spectroscopy.
On-Line Analysis
While the feasibility of measuring butter quality control parameters has been proved in both academic studies and real industrial applications, there are inherent challenges to using NIR spectroscopy as an on-line process control tool. Off-line analysis is easily attainable but does require the transfer of a sample to the instrument. While still much faster and more effective than traditional methods, laboratory instruments are not suitable for real-time analysis.
At-line analysis involves the placement of an instrument in a manufacturing environment and using a sampling system to pull a sample from the process to the instrument. Such methods are also effective but still do not provide real-time feedback and analysis to show both changes in sample parameters and differences in the homogeneity of samples in a process.
On-line analysis involves a sensor being placed either into or above the manufacturing process to provide real-time feedback for the parameters of interest. The nature of and changing physical characteristics of the components of butter can make the hardware needed for monitoring very challenging.
For example, the concentration of butter cream makes it difficult to use transmission (light passes through the material to obtain NIR spectra) for because the light must pass through it to reach the detector sensor. It is also difficult to use reflectance (light reflects off the material to obtain NIR spectra) as the liquid in the cream absorbs a large amount of the light, minimizing the light reflection to the detector sensor.
Advances in hardware, fiber optics, transflectance probes, diffuse reflectance mechanisms, and cleaning mechanisms have greatly contributed to the potential for using NIR spectroscopy as a real-time process control and monitoring tool. Software advances and the use of cloud-based systems have also contributed to the use of NIR spectroscopy as a tool for manufacturing monitoring.

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Recent Advances
Recent work on the use of NIR spectroscopy in butter analysis has focused on new applications for different types of adulteration detection and estimation of oxidative stability parameters. Adulterants in butter can often increase the amount of unsaturated fatty acids which affects oxidative stability parameters like acidity and peroxide index. Advances in hand-held instruments and portability have facilitated the use of NIR spectroscopy for final quality control checks of butter.
Some recent work focused on developing a method using a portable NIR spectrometer to authenticate butteroil and predict quality parameters. Butteroil is a valuable milkfat-based product that is consumed with breads, meats, and popcorn, especially in Brazil. It is also used as the raw material for producing butter cheese.
The high commercial value of butteroil makes it a prime target for adulteration. Strict regulations exist for the guaranteed authenticity of butteroil, but detection of adulteration can be difficult. Potential adulterants include expired butteroil, lard, and cheaper fats like vegetable oil, margarine, and pork fat. The use of expired butteroil is particularly problematic because the expired butteroil has less oxidative stability and the addition of it can degrade the product quickly.
Samples of butteroil with varying concentrations of different adulterants were procured for the study. NIR spectra were collected using a portable NIR spectrometer. Standard methods were used to determine various parameters of interest in the samples, including fatty acid profile, acid value, and peroxide value.
Various types of chemometric models were created during the study. Adulteration models determined the presence of an adulterant, the type of adulterant, and the concentration of the detected adulterant with good accuracy. Quantitative models that measured the oxidative stability parameters showed results good enough for screening purposes. This work proved that a portable NIR spectrometer can be used by producers and inspection agencies for quality control of butteroil at any stage of the supply chain.
Another study compared the use of NIR spectroscopy and Gas Chromatography for detecting butter adulteration. Butter samples were prepared with a known percentage of margarine or pork fat adulterant. After the collection of NIR spectra and standard chemometric data pre-processing and modeling, results were compared using both methods for qualitative detection of an adulterant and quantitative determination of both adulterant concentration and fatty acid content. Fatty acids were categorized as saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA). The GC results showed significant trend changes in certain fatty acids depending on the degree of adulteration. The accuracy of the results for all analysis was comparable using both NIR spectroscopy and GC, making NIR preferable because it is fast, non-invasive, and able to determine multiple parameters with a single measurement while requiring little or no sample preparation.
There have been advances in the use of chemometric modeling algorithms for the monitoring of manufactured products using NIR spectroscopy as well as the use of in-line probes. Advances in both hardware and machine-learning algorithms have enabled the extraction of relevant spectral information for chemometric modeling. This means that older technology could not collect meaningful spectra for analysis nor were past modeling algorithms powerful enough to create accurate and robust models. Coupled together, these two advances have demonstrated great potential when used in tandem for real-time monitoring and process control of butter manufacturing.
Galaxy Scientific
Galaxy Scientific is an industry pioneer in the use of optical Near Infrared Spectroscopy. Our QuasirIRTM family of NIR spectrometers uses Fourier Transform Near-Infrared (FT-NIR) technology for laboratory, field, and process applications.Our passion is innovation and our mission is to develop uniquely robust NIR instruments to solve critical analytical problems in numerous sectors, including butter manufacturing.
For more information about Galaxy Scientific and to contact one of our applications specialists, please visit our website at Galaxy Scientific Inc.
For more detailed discussion on the topics covered in this article, including advanced statistics, overview of the butter manufacturing process, and a review of applications studies for butter analysis using NIR spectroscopy, please visit the following sections on the Galaxy Scientific NIR spectroscopy for food analysis website:
Dairy - NIR-For-Food
Butter Overview - NIR-For-Food
Butter Analysis - NIR-For-Food
References
- Comparison of Butter Quality Parameters Available on the Czech Market with the Use of FT-NIR Spectroscopy – Dvorak, Luzova, Sustova, Mljekarstvo 66 (1), 73-80 (2016). https://hrcak.srce.hr/file/222331
- At-Line Near-Infrared Spectroscopy for Prediction of the Solid Fat Content of Milk Fat from New Zealand Butter – Meagher, Holroyf, Illingworth, et al., Journal of Agricultural and Food Chemistry, 2007, 55, 2791-2796. https://pubs.acs.org/doi/abs/10.1021/jf063215m?journalCode=jafcau
- Robust New NIRS Coupled with Multivariate Methods for the Detection and Quantification of Tallow Adulteration in Clarified Butter Samples – Mabood, Abbas, Jabeen, et al., Food Additives & Contaminants: Part A, 35:3, 404-411. https://tandfonline.com/doi/abs/10.1080/19440049.2017.1418090?journalCode=tfac20

This information has been sourced, reviewed and adapted from materials provided by Galaxy Scientific Inc.
For more information on this source, please visit Galaxy Scientific Inc.