Published: August 09, 2011 r2011 American Chemical Society 9497 dx.doi.org/10.1021/jf2012979 | J. Agric. Food Chem. 2011, 59, 9497–9505 ARTICLE pubs.acs.org/JAFC 1 H NMR Metabolite Fingerprint and Pattern Recognition of Mullet (Mugil cephalus) Bottarga Emanuela Locci, Cristina Piras, Simone Mereu, Flaminia Cesare Marincola, and Paola Scano* Dipartimento di Scienze Chimiche, Universit  a degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.S. 554  Bivio per Sestu, 09042 Cagliari, Italy ABSTRACT: Nuclear magnetic resonance (NMR) spectroscopy combined with multivariate data analysis (MVA) was used to investigate the molecular components of the aqueous extract of samples of bottarga, that is, salted and dried mullet (Mugil cephalus) roe, manufactured in Sardinia (Italy) from mullets of known and unknown geographical provenience. Principal component analysis (PCA) applied to the processed 1 H NMR spectra indicated that samples tend to cluster according to their geographical origin and also on the basis of storage and manufacturing procedures. The most important metabolites that characterized grouping of samples are the free amino acids methionine (Met), glutamate (Glu), histidine (His), phenylalanine (Phe), tyrosine (Tyr), and isoleucine (Ile); trimethylamine (TMA) and dimethylamine (DMA), both biomarkers of degradation; nucleotides and derivatives; choline (Cho) and phosphorylcholine (P-cho); and lactate (Lac). KEYWORDS: bottarga, aqueous extract, metabolite profile, 1 H NMR, MVA ’ INTRODUCTION The eviscerated roes of striped mullet (Mugil cephalus) are manufactured in several countries, and the salted and dried product can be found worldwide under different names and typologies. The Mediterranean island of Sardinia (Italy) has a long tradition in manufacturing mullet roes to obtain a product called “bottarga”. In recent years, Sardinian bottarga, which is sold as whole ovaries (“in baffe”) or grated in jars, has become so increasingly popular in international markets that mullets of the Mediterranean sea are not enough to satisfy the request of this product. As a result, the Sardinian producers must turn their attention to other fishing areas located in different regions of the globe for roe supplies. Indeed, raw roes are purchased from distributors located mainly in FAO 31, 34, and 41 fishing areas. Even if the raw material is not necessarily original to the island, Sardinian bottarga has its own peculiar rheological and organo- leptic profile due to the skills of the local producers, inheritors of an ancient tradition in processing this delicacy. For this reason, Sardinian manufacturers of bottarga are requesting a Protected Geographical Indication (PGI) designation for this product. The globalization of food markets and the relative ease with which food commodities are transported between countries increase the awareness of consumers about the origin of the foods they eat. As far as fishery products are concerned, European legislation establishes that the FAO area in which fish was caught should be part of the information available to consumers. 1 This applies also to processed products such as bottarga. It is therefore of great importance to be able to determine the geographical origin of fish, especially when used in preparing processes to perform authentication and/or traceability studies useful to enforce labeling regulations. Traditional methods for species authentication of fish include DNA and protein analyses. 2 Recently, the analysis of metabolite profiles by high-resolution nuclear magnetic resonance (NMR) spectroscopy has been proposed as an alternative method for the authentication of seafood. 38 In the past two decades 1 H NMR has proved to be a fast and versatile technique, useful both for compositional analysis and for rapid screening of food, allowing the detection of the major metabolites in a single spectrum, and, when associated with multivariate data analysis (MVA), can provide a suitable tool for comparing, discriminating, or classifying samples on the basis of their metabolic profile. 7,9 The free metabolite pool found in the aqueous phase of animal and vegetable matrices reflects the metabolic processes of the living organism, and it can be characteristic of individuals from a specific geographical area but can also reflect the chemical and physical transformations that can take place during storage of the raw material, manufac- turing, and shelf life. It includes free amino acids, nucleotides and related compounds, organic bases, sugars, and others, whereas the molecular pool soluble in organic solvent includes fatty acids and related lipids. As for the majority of marine products, which are rich in health-beneficial ω-3 fatty acids, most of the investiga- tions on salted and dried mullet roes concern the lipid compo- nents and, particularly, the lipid classes and fatty acid composition (see ref 10 and literature cited therein). To the authors’ knowledge, different from the lipid components, inves- tigations on the low molecular weight compounds of bottarga are rare in the literature. 11 The aim of this work was to evaluate whether the 1 H NMR low molecular weight metabolite profile of bottarga can be consid- ered a valid tool to characterize bottarga samples having different geographical origins and production processing protocols. For this purpose, we recorded the 1 H NMR spectra of the aqueous extract of 25 samples of bottarga, manufactured in Sardinia from mullets of known and unknown geographical origin and com- mercialized either in baffe or grated in jars. Principal component analysis (PCA) was applied to the 1 H NMR spectral data to Received: April 1, 2011 Revised: August 8, 2011 Accepted: August 9, 2011