**6. Conclusion**

The most widely used ionization methods for oligosaccharides are matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI), coupled with tandem techniques such as collision-induced dissociation (CID). Such advances have improved carbohydrate research with mass spectrometry. The tandem mass spectrometry (MS/MS) has been used for detailed structural analysis of oligosaccharide molecules in which a molecular ion is selected by a first stage of MS, which undergoes activation and fragmentation, and the product ions are analyzed to provide information about the sequence monosaccharide composi-

Milk oligosaccharides have been analyzed using tandem mass spectrometry such as collisioninduced dissociation (CID) and infrared multiphoton dissociation (IRMPD) [112]. A comprehensive label-free procedure to identify and quantify milk oligosaccharides and other glycans using nano-liquid chromatography-time of flight MS was recently developed [113]. During this study, MALDI-Fourier transform ion cyclotron resonance (FTICR) was used for accurate mass measurement compositional analysis. FTICR MS provides exceptional mass accuracy at even few parts per million with extremely high mass resolution and has been extensively and successfully used in complex samples. Oligosaccharides in bovine cheese whey permeate were characterized by a combination of nanoelectrospray (nESI)-FTICR-MS and MALDI-FTICR-MS, and this method was possible to identify 15 (8 were neutral and 7 were acidic) milk oligosaccharides [18]. Recently, Mehra et al. [28] identified 25 oligosaccharides including 6 high molecular weight fucosylated oligosaccharides in a mother liquor of dairy streams using MALDI-FTICR mass spectrometer, and the researchers also confirmed the fucosylated oligosaccharides composition and putative structure by using accurate tandem mass spectrometry.

Many different analytical techniques have been used to elucidate the free glycan profile present in milk samples. Compared with LC-MS and GC-MS, one of the advantages of NMR spectroscopy is the direct and quantitative relationship between the molar concentration and the intensity of the NMRs. For instance, NMR has played an important role in the structural characterization of free oligosaccharides in human milk [114–117]. Monakhova et al. [118] suggest the use of NMR spectroscopy as screening tool to validate nutrition labeling of lactose-free

Lactose is used as an agglomerating agent, a flavor enhancer, and a diluent in many foods, beverages, and bakery and confectionery products. In the pharmaceutical industry, it is employed as a diluent in tablets and a carrier in medicines [119, 120]. In the last year, the interest in lactulose has increased to a high extent due to its application in the pharmaceutical and food industry. Lactulose is considered as a prebiotic because it promotes the proliferation of *Bifidobacteria* in the human intestine. Therefore, this disaccharide is used as a food supplement in pediatric and geriatric diets [121] as well as for prevention and treatment of chronic constipation, portal systemic encephalopathy, and other intestinal or hepatical disorders [122]. It has been suggested that lactulose has anti-inflammatory properties, which make it an appropriate and useful adjunctive treatment to inflammatory bowel diseases in humans [123].

tions, linkages, and locations of various modifications [111].

136 Technological Approaches for Novel Applications in Dairy Processing

**4.8. Nuclear magnetic resonance (NMR)**

milk, reporting a detection limit of 30 mg/L.

**5. Applications of fractionated carbohydrates**

There are several fractionations and analytical techniques currently being used for the determination of carbohydrates in different milk and milk products. A problem with studying carbohydrate bioactivities is the limited access to well-defined oligosaccharides. Purification of oligosaccharides from natural sources is laborious, and it is difficult to obtain preparation free of contaminants. In addition, the nonlinear nature of oligosaccharides creates a high structural diversity and their overall complexity makes it difficult for a single analytical method to characterize them. Numerous health benefits of milk oligosaccharides and lactose derivatives are well established, including the pharmaceutical and food applications.
