# 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)
The study of milk samples contaminated with deionized water revealed a decrease in conductivity using a measurement device made up of a bioimpedance sensor, an impedance analyzer, and a computer or laptop for data gathering and processing. The study's findings demonstrated that milk impedance spectra can be utilized as a low-cost, reliable, and accessible method to regulate milk quality in the dairy industry. This method is suited for identifying changes in milk [81]. [PERSON] et al. investigated a non-contact technique for using the apparatus with the milk sample, retaining its consistency and quality, and making it reusable for another test. However, there are some drawbacks to this approach as well. The milk's fat content, which alters its density and, as a result, directly influences the refractive index and, thus, the optical sensor's reading, is the primary factor that has a negative impact. It has been shown that a sample of buffalo milk altered in proportion by approximately 70% will provide readings identical to those of a pure sample of cow's milk, hence, it is also necessary to specify the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Adulterant** & **Detection Technique** & **Advantage** & **Disadvantage** & **Reference** \\ \hline Formaldehyde & Optical sensor & \begin{tabular}{c} It could be used in contact \\ with aqueous solutions \\ because it is insoluble in \\ water. Low cost, easy to use. \\ \end{tabular} & [75] \\ \hline Formaldehyde & HPLC-UV & \begin{tabular}{c} Simple, accurate, \\ interference-free method \\ \end{tabular} & \begin{tabular}{c} The need for the \\ derivatization reaction. \\ \end{tabular} & [76] \\ \hline Formaldehyde & Smartphone-based digital & \begin{tabular}{c} An innovative, quick, and \\ affordable method. No toxic \\ images \\ \end{tabular} & \begin{tabular}{c} The need for chemical \\ derivatization. \\ \end{tabular} & [77] \\ \hline Formaldehyde & \begin{tabular}{c} Time-Domain magnetic \\ resonance (TD-NMR) \\ \end{tabular} & \begin{tabular}{c} Excellent repeatability and \\ reproducibility. It does not \\ require the preparation of \\ samples. \\ \end{tabular} & Must be used together with \\ \hline Hypochlorite & \begin{tabular}{c} Luminescence Nanoprobe \\ in the Near-Infrared-II \\ Window \\ \end{tabular} & \begin{tabular}{c} Sensitive and selective \\ detection. Low-cost, \\ non-invasive detection. \\ \end{tabular} & \begin{tabular}{c} The difficult design of \\ nanocrystals. \\ \end{tabular} & [79] \\ \hline Hypochlorite & \begin{tabular}{c} A paired emitter–detector \\ diode-based photometer \\ \end{tabular} & \
\begin{tabular}{c} The photometer has the \\ potential to be portable and \\ can be used by consumers. \\ \end{tabular} &
\begin{tabular}{c} Supplementing with a \\ potentiometer and a phone \\ app. \\ \end{tabular} & [80] \\ \hline Abbreviations: HPLC = high-performance liquid chromatography, TD-NMR = time-domain nuclear magnetic. \\ \end{tabular}
\end{table} 
Table 6: _Cont._origin of the species from which the milk is derived during the analysis. This system's ability to detect adulteration with water is really impressive, but it needs to be improved in a number of ways, including by describing the milk's fat content and species as well as bringing it to room temperature to get more accurate results [83]. Different Methods of Species Identification  
Currently, the analytical methods based on DNA analysis have progressed rapidly and have been successfully applied to testing the authenticity of milk [3]. Most DNA tests allow the identification of the species of origin in processed foods such as dairy products and are based on the polymerase chain reaction (PCR) technique. DNA-based methods have clear advantages, such as simplicity, high specificity, and sensitivity. Moreover, the ubiquity of nucleic acids in each cell type and their superior stability compared to proteins are two of their most important advantages.