# A Review of Milk Frauds and Adulterations from a Technological Perspective
## 3 Results and Discussion
### Methods for Detecting Adulterants in Milk
#### 3.2.3. Instrumental Methods (Quantitative)
This allowed for the quick detection of urea at concentrations as low as \(10^{-8}\) M [64]. The use of thermal biosensors in milk testing is increasing, as are the demands for such sensors that are simple to operate and have long-term stability. This class of biosensors is based on the heat record generated during a biological reaction. The method of determining urea offers the advantages of enzymatic selectivity, rapid analysis time, and low reagent use. A flow injection analysis-enzyme thermistor (FIA-ET) biosensor was created by covalently immobilizing the enzyme urease on glass with regulated pores and packing it in a column into the thermistor, which selectively degraded the urea in the test sample. In addition, the specific heat produced by the urea hydrolysis process was shown to be related to the content of urea in the milk sample [65]. Fat Content Adulteration Identification Techniques  
Liquid chromatography (LC) and gas chromatography (GC), particularly when combined with mass spectrometry (MS), have both recently been proposed as analytical methods for quick screening or selective confirmation of the quality and authenticity of milk fat. Due to the ability to observe and compare fatty acids and triacylglycerols to reference standards, the gas chromatographic method is most often used to analyze the origin of fat. According to the number of carbon atoms, the milk triacylglycerolslases are separated into fatty acids using the gas-chromatographic method. It also allows the simultaneous determination of 60 fatty acids in each sample, and the spectrum of fatty acids can be observed with the help of chromatograms. There are a number of factors that intervene in the separation of fatty acids such as the temperature of the column, the type of the carrier phase, the speed with which it circulates, the type and thickness of the film of the stationary phase, the inner diameter of the column, the pressure of the vapors in the column, the length of the column, and the volume of the sample that was injected [66; 67; 68]. Precisely because determining the purity of milk fat is as difficult as identifying seawater in ocean water, differences in fatty acid composition are most useful for this purpose. The gas-chromatographic method proved its effectiveness in a study conducted by [PERSON] et al., in which they investigated the identification of adulteration of milk fat with soybean oil and buffalo depot fat. They were based on the fact that soybean oil has a high amount of linoleic acid and buffalo depot fat has a high content of oleic acid, both of which are devoid of short-chain fatty acids, characteristic of fats of dairy origin. These markers led to the identification of 5% \(v/v\) added of both adulterants, and the method proved to be a specific quantitative method [69]. Therefore, the gas-chromatographic method is a laborious method in terms of sample processing, requiring reagents, expensive equipment, and qualified personnel, but it is a precise method for determining the spectrum of fatty acids contained in milk samples [66; 67; 68]. Regarding the existence of another method to identify the adulteration of milk fat, [PERSON] et al. studied the possible use of fluorescence spectroscopy in the identification of samples according to their fat source and the detection of milk fat adulterated with vegetable oil. On the other hand, spectroscopic techniques provide information on a mixture's constituents in a single spectrum, typically without the need for derivatization. For the classification of various types of milk or the detection of adulteration, statistical analysis is necessary when the spectrum differences are not always clearly visible [33; 70]. In addition, [PERSON] et al. evaluated the potential application of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-QTOF MS) as an effective technique for the analysis of oils and fats by providing characteristic profiles of triacylglycerlycerides.