# MALDI-TOF Mass Spectrometry Applications for Food Fraud Detection
## 2 MALDI Applications  
### Milk and Dairy Products  
Due to their high nutritional value, milk and derived products are largely consumed all over the world. According to the Food and Agriculture Organization of the United Nations (FAO), worldwide milk production has grown from 522 to 798 million tons in three decades (1986-2016) [24] and was expected to grow in 2020 to 859 million tons [25]. The increase in consumption also increases the number of dishonest producers willing to commit fraud to increase their earnings, making the safety and authenticity of milk and derived products an area of growing attention and concern, as demonstrated by several regulations and governing bodies [26; 27]. Traditionally, milk dilution by water has been the most common illegal practice, together with the selling of skimmed milk and semi-skimmed milk instead of whole milk. As detection methods technologies has improved, fraudulent suppliers evolved [28] towards most sophisticated fraudulent approaches, such as the addition of milk anhydrous products (caseins and caseinate, milk protein concentrate, whey proteins) to liquid milk and the mixing of high-quality milk, such as buffalo, sheep, and goat, with less expensive products, such as cow milk. Many MALDI-based analytical methods have been developed and improved in the last years to assess the authenticity of milk and dairy products. Buffalo milk has been extensively investigated by different MALDI proteomic approaches searching for possible adulteration. [PERSON] and co-workers have developed two different methods for the identification of adulteration of water buffalo and sheep milk and water buffalo mozzarella, respectively. In the first work [29], the investigation was performed on raw buffalo and sheep milk samples. The determination of the presence of bovine milk or the addition of powdered milk to fresh raw milk was accomplished by evaluating the protein profiles coming from the most abundant whey proteins, lactalbumin, and lactoglobulins. In the second work [30], patterns of the same whey proteins were obtained from the direct analysis of water buffalo mozzarella cheese, which was able to differentiate between mozzarella cheeses made from pure water buffalo milk or from mixtures of bovine-sheep-buffalo millks. Interesting quality information on the partial resistance of the detected proteins to the thermal and enzymatic processes involved in the cheese production was also inferred. In both methods, mixtures with different percentages of less expensive milk added to water buffalo milk were prepared, and detection limits below 5% were always obtained in adulterated milk or cheese, respectively. The strategies were also fast, accurate, and practically did not require sample pre-treatment. [PERSON] at al. have successfully optimized an integrated MALDI-TOF platform [31] for obtaining milk peptidomic/proteomic profiles to detect the addition of either nondeclared bovine material to water buffalo, goat, and ovine millks, or of powdered bovine milk to the fresh bovine milk. Milk samples were directly analyzed permitting a fast individuation of illegal adulterations at protein and peptide level and allowing the identification of unique diagnostic ions of thermal treatment in different types of commercial milks. A further MALDI proteomic study for the detection of ricotta buffalo cheese adulteration with bovine milk by obtaining peptide profiles for both matrices was developed [32], followed by the search for signals that could represent specific markers for each type of dairy product. A peptide marker corresponding to the region 149-162 of \(\beta\)-lactoglobulin was correlated to the univocal presence of bovine milk in ricotta buffalo cheese at a 5% level. According to the European reference method, the fraudulent addition of bovine milk in water buffalo milk can be individuated by concomitant isoelectric focusing detection of bovine \(\gamma_{2}\)- and \(\gamma_{3}\)-casein fragments after plasminolysis.