**1. Introduction**

Food products are very complex mixtures constituted by a great variability of naturally occurring compounds such as lipids, carbohydrates, proteins, vitamins, organic acids, and volatile organic compounds, among others. Moreover, they can also contain many other substances coming from agrochemical treatments and technological processes, or even migrating from the materials employed in food packaging, which sometimes are contaminants.

Food manufacturers, researchers, and society in general are also becoming very interested in the quality of food products, not only from the nutritional point of view but also in relation to food safety issues or regarding the presence of bioactive substances with beneficial properties for consumers (functional foods, nutraceuticals, etc.). Aspects related to the cultivation production region of natural food products (fruits, vegetables, etc.), as well as the cultivation techniques employed, begin to be also of great interest to the final consumers, giving rise to the consideration of the protected designations of origin (PDO) of natural foodstuffs as important food quality attributes.

Nowadays, the food supply production is worldwide distributed and consequently a globalized issue. Although international and local regulatory bodies have established important rules in the labeling of food products, in general, it is often almost impossible to know the real origin of most of the components of a given food product, especially those that have been processed. Within this context, considering the complexity of the food chain and that many players are involved between production and consumption; food manipulation and adulteration practices are raising because it is in fact much easier to conduct fraud without being easily detected. For example, Moore et al. collected information from published articles in scholarly journals and general media, organized it into a database, and reviewed and analyzed the data to identify trends within food ingredient fraud practices from 1980 to 2010 [1]. They observed that olive oil, milk, honey, and saffron were the most common targets for adulteration reported in scholarly journals and potentially harmful issues identified include spices diluted with lead chromate and lead tetraoxide, substitution of Chinese star anise with toxic Japanese star anise, and melamine adulteration of high protein content foods.

Food adulteration practices have a long history and dates back to times when trading began. In general, food adulteration is carried out to increase volume, to mask the presence of inferior quality components and to replace the authentic substances for the seller's economic gain. However, it must be considered that the deliberate adulteration of food and its misrepresentation to deceive final consumers is illegal worldwide, having not only economic consequences, but also representing important health issues when prohibited substances are added to deceive the organoleptic properties of the final food product or when the adulterant can produce allergy episodes. Thus, the development of new analytical methodologies to guarantee food integrity and authenticity is required, also considering that food adulteration has become increasingly sophisticated, often being specially designed to avoid detection through routine analysis approaches.

The analysis of food products is difficult not only because of the complexity and diversity of sample matrices but also due to the great variability of compounds that can be present. In addition, food components differ in polarity, structures, as well as in concentration levels, going from components at grams per kilogram level to those found at trace level concentrations (low μg/kg, ng/kg, etc.). These are important aspects to consider when selecting the analytical approach to employ. Sample treatment and sample extraction procedures, separation and determination approaches, and identification and confirmation strategies need to be considered simultaneously when addressing the development of an analytical method in food integrity and authenticity analyses. Nowadays, liquid chromatography coupled to mass spectrometry (LC-MS) or to tandem mass spectrometry (LC-MS/MS) is among the most effective analytical techniques for the structural characterization and analysis of food products. The appearance of ultra-high performance liquid chromatography (UHPLC) methodologies, either using sub-2 μm particle packed columns or porous-shell columns (with sub-3 μm superficially porous particles), opened up new possibilities to achieve high throughput chromatographic analytical separations, 5- to 10-fold faster than with conventional LC methodologies, while keeping or even improving chromatographic resolutions [2]. The use of liquid chromatography coupled to high resolution mass

**5**

*The Role of Liquid Chromatography-Mass Spectrometry in Food Integrity and Authenticity*

spectrometry (LC-HRMS) and accurate mass measurements have recently gained huge popularity due to the great ability of these methodologies to provide more comprehensive information regarding the exact molecular mass, elemental composition, and detailed molecular structure of a given compound. In comparison to classical low resolution mass spectrometry (LRMS) techniques, HRMS allows to differentiate isobaric compounds (substances with the same nominal mass-tocharge ratio but different elemental compositions). Moreover, the high resolution attainable with HRMS favors the simplification of sample treatment and preparation procedures, leading to faster analytical methodologies with less and simple sample manipulation. HRMS allows to perform both screening and quantitation in a single run, including targeted, suspect, and non-targeted analyses. Another important advantage of HRMS, especially when data is stored in full-scan mode, is the possibility of later stage retrospective analysis, allowing the identification and determination of new unknown or suspected compounds in a previously

An important aspect in food products, especially those of plant origin, is that the presence, distribution, and content of many bioactive substances is related to many food features such as the variety and species of the products, the degree of maturation in the fruits and vegetables employed, the geographical production areas, the growing and manufacturing practices used, etc. A similar consideration can be mentioned for food products of animal origin, where many substances present in the final product will be related to the animal species, the farming practices employed, the animal stress, etc. Therefore, food chemical profiling, for instance of amino acids, biogenic amines, alcohols, aldehydes, esters, acids, terpenes, polyphenols, etc., can be exploited as sample data descriptors to achieve the characteriza-

Regarding chemical profiling in food integrity and authenticity by LC-MS and LC-HRMS methodologies, two main approaches are typically employed: targeted and non-targeted analyses. Targeted approaches can be performed by both LC-MS(/MS) and LC-HRMS techniques and are based on the specific determination of a given group of known selected chemicals, or a group of chemicals belonging to the same family or with a similar structural feature. The concentrations (or peak signals) of these targeted compounds are then used as food features (markers) to address food integrity and authenticity. This approach requires, in general, a previous quantitation step using standards for each targeted component. However, when dealing with food products, which as previously commented are very complex matrices, the quantitation of some chemicals may be a difficult task, especially due to the possibility of unknown interfering compounds. In contrast, non-targeted approaches (based on metabolomic fingerprinting) are mainly employed with LC-HRMS techniques. These fingerprinting approaches are based on untargeted analysis of instrumental responses without assuming any previous knowledge of relevant or irrelevant food components. In the case of LC-HRMS, food sample fingerprinting information consists, in general, of peak intensity values recorded as

Due to the complexity of food sample matrices and the variability of chemical components that can be present, the amount of chemical data that can be extracted, especially when dealing with non-targeted LC-HRMS fingerprinting approaches, is huge. As a consequence, in order to extract (bio)chemical information from the sample data sets able to characterize, classify and authenticate food products, chemometric data treatment methodologies are necessary. Multivariate methods such as principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) are among the most employed chemometric methods for explor-

atory and classification purposes in food integrity and authenticity [4].

tion, classification, and authentication of food products.

a function of *m/z* and retention times [3].

*DOI: http://dx.doi.org/10.5772/intechopen.85087*

analyzed food sample.

#### *The Role of Liquid Chromatography-Mass Spectrometry in Food Integrity and Authenticity DOI: http://dx.doi.org/10.5772/intechopen.85087*

spectrometry (LC-HRMS) and accurate mass measurements have recently gained huge popularity due to the great ability of these methodologies to provide more comprehensive information regarding the exact molecular mass, elemental composition, and detailed molecular structure of a given compound. In comparison to classical low resolution mass spectrometry (LRMS) techniques, HRMS allows to differentiate isobaric compounds (substances with the same nominal mass-tocharge ratio but different elemental compositions). Moreover, the high resolution attainable with HRMS favors the simplification of sample treatment and preparation procedures, leading to faster analytical methodologies with less and simple sample manipulation. HRMS allows to perform both screening and quantitation in a single run, including targeted, suspect, and non-targeted analyses. Another important advantage of HRMS, especially when data is stored in full-scan mode, is the possibility of later stage retrospective analysis, allowing the identification and determination of new unknown or suspected compounds in a previously analyzed food sample.

An important aspect in food products, especially those of plant origin, is that the presence, distribution, and content of many bioactive substances is related to many food features such as the variety and species of the products, the degree of maturation in the fruits and vegetables employed, the geographical production areas, the growing and manufacturing practices used, etc. A similar consideration can be mentioned for food products of animal origin, where many substances present in the final product will be related to the animal species, the farming practices employed, the animal stress, etc. Therefore, food chemical profiling, for instance of amino acids, biogenic amines, alcohols, aldehydes, esters, acids, terpenes, polyphenols, etc., can be exploited as sample data descriptors to achieve the characterization, classification, and authentication of food products.

Regarding chemical profiling in food integrity and authenticity by LC-MS and LC-HRMS methodologies, two main approaches are typically employed: targeted and non-targeted analyses. Targeted approaches can be performed by both LC-MS(/MS) and LC-HRMS techniques and are based on the specific determination of a given group of known selected chemicals, or a group of chemicals belonging to the same family or with a similar structural feature. The concentrations (or peak signals) of these targeted compounds are then used as food features (markers) to address food integrity and authenticity. This approach requires, in general, a previous quantitation step using standards for each targeted component. However, when dealing with food products, which as previously commented are very complex matrices, the quantitation of some chemicals may be a difficult task, especially due to the possibility of unknown interfering compounds. In contrast, non-targeted approaches (based on metabolomic fingerprinting) are mainly employed with LC-HRMS techniques. These fingerprinting approaches are based on untargeted analysis of instrumental responses without assuming any previous knowledge of relevant or irrelevant food components. In the case of LC-HRMS, food sample fingerprinting information consists, in general, of peak intensity values recorded as a function of *m/z* and retention times [3].

Due to the complexity of food sample matrices and the variability of chemical components that can be present, the amount of chemical data that can be extracted, especially when dealing with non-targeted LC-HRMS fingerprinting approaches, is huge. As a consequence, in order to extract (bio)chemical information from the sample data sets able to characterize, classify and authenticate food products, chemometric data treatment methodologies are necessary. Multivariate methods such as principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) are among the most employed chemometric methods for exploratory and classification purposes in food integrity and authenticity [4].

*Mass Spectrometry - Future Perceptions and Applications*

melamine adulteration of high protein content foods.

to avoid detection through routine analysis approaches.

tant food quality attributes.

substances with beneficial properties for consumers (functional foods, nutraceuticals, etc.). Aspects related to the cultivation production region of natural food products (fruits, vegetables, etc.), as well as the cultivation techniques employed, begin to be also of great interest to the final consumers, giving rise to the consideration of the protected designations of origin (PDO) of natural foodstuffs as impor-

Nowadays, the food supply production is worldwide distributed and consequently a globalized issue. Although international and local regulatory bodies have established important rules in the labeling of food products, in general, it is often almost impossible to know the real origin of most of the components of a given food product, especially those that have been processed. Within this context, considering the complexity of the food chain and that many players are involved between production and consumption; food manipulation and adulteration practices are raising because it is in fact much easier to conduct fraud without being easily detected. For example, Moore et al. collected information from published articles in scholarly journals and general media, organized it into a database, and reviewed and analyzed the data to identify trends within food ingredient fraud practices from 1980 to 2010 [1]. They observed that olive oil, milk, honey, and saffron were the most common targets for adulteration reported in scholarly journals and potentially harmful issues identified include spices diluted with lead chromate and lead tetraoxide, substitution of Chinese star anise with toxic Japanese star anise, and

Food adulteration practices have a long history and dates back to times when trading began. In general, food adulteration is carried out to increase volume, to mask the presence of inferior quality components and to replace the authentic substances for the seller's economic gain. However, it must be considered that the deliberate adulteration of food and its misrepresentation to deceive final consumers is illegal worldwide, having not only economic consequences, but also representing important health issues when prohibited substances are added to deceive the organoleptic properties of the final food product or when the adulterant can produce allergy episodes. Thus, the development of new analytical methodologies to guarantee food integrity and authenticity is required, also considering that food adulteration has become increasingly sophisticated, often being specially designed

The analysis of food products is difficult not only because of the complexity and diversity of sample matrices but also due to the great variability of compounds that can be present. In addition, food components differ in polarity, structures, as well as in concentration levels, going from components at grams per kilogram level to those found at trace level concentrations (low μg/kg, ng/kg, etc.). These are important aspects to consider when selecting the analytical approach to employ. Sample treatment and sample extraction procedures, separation and determination approaches, and identification and confirmation strategies need to be considered simultaneously when addressing the development of an analytical method in food integrity and authenticity analyses. Nowadays, liquid chromatography coupled to mass spectrometry (LC-MS) or to tandem mass spectrometry (LC-MS/MS) is among the most effective analytical techniques for the structural characterization and analysis of food products. The appearance of ultra-high performance liquid chromatography (UHPLC) methodologies, either using sub-2 μm particle packed columns or porous-shell columns (with sub-3 μm superficially porous particles), opened up new possibilities to achieve high throughput chromatographic analytical separations, 5- to 10-fold faster than with conventional LC methodologies, while keeping or even improving chromatographic resolutions [2]. The use of liquid chromatography coupled to high resolution mass

**4**

In the next sections, several examples dealing with targeted and non-targeted strategies based on LC-MS(/MS) and LC-HRMS methodologies, in combination with chemometrics, to guarantee food integrity and authenticity will be addressed.
