Alessandra Ciampa

NMR approach for monitoring post-mortem changes in Atlantic salmon fillets stored at 0 and 4°C.

High resolution NMR technique has been used to monitor post-mortem changes in salmon (Salmo salar) fillets upon storage at 4 and 0°C. Thirty-one different fish metabolites influencing freshness and taste properties have been unequivocally assigned by NMR using either available standard compounds or ad hoc acquired 2D (1)H-(1)H TOCSY and (1)H-(13)С HSQC spectra. The monitored fish metabolites include amino acids, dipeptides, sugars, vitamins, biogenic amines, as well as different products of the ATP degradation. The detection and monitoring of biogenic amines by NMR, upon fish storage, is information of interest for consumers, since some of these compounds are toxic. The data from this study shows that NMR spectroscopy also provides the amount of all metabolites necessary for the calculation of the K-index used to express fish freshness. A good correlation was found between the K-index increase and the formation of the undesired biogenic amines. The metabolite concentrations and the K-index found in this work were compared and found coherent with literature data. The performed study reveals the strengths and the suitability of the NMR approach to monitor different biochemical processes occurring during fish storage and qualitatively and quantitatively characterise fish metabolites determining fish quality.

Changes in the Amino Acid Composition of Bogue (Boops boops) Fish during Storage at Different Temperatures by 1H-NMR Spectroscopy

Nuclear magnetic resonance spectroscopy was employed to obtain information about the changes occurring in Bogue (Boops boops) fish during storage. For this purpose, 1H-NMR spectra were recorded at 600 MHz on trichloroacetic acid extracts of fish flesh stored over a 15 days period both at 4 °C and on ice. Such spectra allowed the identification and quantification of amino acids, together with the main organic acids and alcohols. The concentration of acidic and basic free amino acids was generally found to increase and decrease during storage, respectively. These concentration changes were slow during the first days, as a consequence of protein autolysis, and at higher rates afterward, resulting from microbial development. Two of the amino acids that showed the greatest concentration change were alanine and glycine, known to have a key role in determining the individual taste of different fish species. The concentration of serine decreased during storage, as highlighted in the literature for frozen fish samples. Differences in the amino acids concentration trends were found to be related to the different storage temperatures from day 4 onwards.

The foodomics approach for the evaluation of protein bioaccessibility in processed meat upon in vitro digestion

The present work describes a foodomics protocol coupling an in vitro static simulation of digestion to a combination of omics techniques, to grant an overview of the protein digestibility of a meat‐based food, namely Bresaola. The proteolytic activity mediated by the digestive enzymes is evaluated through Bradford and SDS‐PAGE assays, combined to NMR relaxometry and spectroscopy, to obtain information ranging from the microscopic to the molecular level, respectively. The simple proteomics tool adopted here points out that a clear increase of bioaccessible proteins occurs in the gastric phase, rapidly disappearing during the following duodenal digestion. However, SDS‐PAGE and the Bradford assay cannot follow the fate of the digested proteins when the products are sized <5 kDa. Conversely, NMR spectroscopy is able to capture the overall molecular profile of small fragments and peptides, which are mainly formed during the duodenal phase, thus giving the kinetics of the whole digestion process. Time domain NMR relaxometry, finally, detects the swelling phenomenon occurring during the gastric phase, when the digestion fluid enters the meat matrix.

Effects of arsenic on soil–plant systems

Arsenic is a highly toxic element and its presence in food composites is a matter of concern for the well-being of both humans and animals. The aim of this study was to evaluate the effects of arsenic on food vegetables and polluted soils. Vicia faba seedlings grown on polluted soils were used to evaluate the phytotoxic and genotoxic effects by comet assay. The results of these tests were dependent upon different types of soils. We studied different types of soils and contamination effects on Raphanus sativus L. and Lactuca sativa L. cropping by using magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR). For both analytical approaches, we found indicators correlated to As contamination, chemical for NMR, i.e. modification of composition, and morphological for MRI, i.e reorganisation of internal tissues. Samples of vegetables were collected to analyse their micro- and macronutrient contents and level of metals using inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis, which confirms the results obtained by MRI.

Cherry tomatoes metabolic profile determined by 1H-High Resolution-NMR spectroscopy as influenced by growing season

The content of the most valuable metabolites present in the lipophilic fraction of Protected Geographical Indication cherry tomatoes produced in Pachino (Italy) was observed for 2 cultivated varieties, i.e. cv. Naomi and cv. Shiren, over a period of 3 years in order to observe variations due to relevant climatic parameters, e.g. solar radiation and average temperature, characterising different seasons. (1)H-NMR spectroscopy was applied and spectral data were processed by means of Principal Component Analysis (PCA). We found that the metabolic profile was different for the two considered cultivated varieties and they were differently affected by climatic conditions. Major metabolites influenced by cropping period were α-tocopherol and the unsaturated lipid fraction in Naomi cherry tomatoes, and chlorophylls and phospholipids in Shiren variety, respectively. These results furnished useful information on seasonal dynamics of such important nutritional metabolites contained in tomatoes, confirming also NMR spectroscopy as powerful tool to define a complete metabolic profiling.

Time Domain Measurements and High Resolution Spectroscopy are Powerful Nuclear Magnetic Resonance Approaches Suitable to Evaluate the In Vitro Digestion of Protein-rich Food Products

It is commonly accepted that the digestibility of the proteins of a protein-rich food can be affected by the spatial arrangement of its components, so that two foods with similar macronutrient composition may show different digestibility if produced through different technological processes. Few studies address this topic in vivo, due to the difficulties in setting up a suitable protocol, while a great variety of in vitro digestion tests are described in the literature. Recently the authors of the present paper described one protocol mostly based on Nuclear Magnetic Resonance (NMR) in its Time Domain (TD) and high resolution (HR) variants. TD-NMR measurements at 0.23–0.46 Tesla can be applied to get information about the spatial arrangements of several kinds of food through the interactions between biopolymers and water. Amino acids, peptides and proteins solubilised by digestion can be simultaneously observed by means of HR-NMR, which offers qualitative information about the size distribution of macromolecules by means of the measure of signal linewidth. The present paper focuses on practical aspects of the application of TD- and HR-NMR to the setting up of protocols for the study of the relationships between the structure of protein-rich foods and their digestibility. For this purpose, details on a recently published study describing the protocol set for evaluating the in vitro digestion of Parmigiano cheese by TD- and HR-NMR are given. Some comparisons with other matrices, such as fresh and cured meat, are provided as well.

Normalization is a Necessary Step in NMR Data Processing: Finding the Right Scaling Factors

Conventionally, the analytical procedure can be restricted to the identification and quantification of a selected number of pre-defined metabolites in a biological sample. This process is called metabolite profiling (or, sometimes, metabolic profiling). 2 For example, pre-defined metabolites may belong to a class of compounds (such as polar lipids, isoprenoids, or carbohydrates), or be narrowed down to members of particular pathways. The term metabolite profiling is frequently used in the specific context of drug research in the description of catabolic degradation of an applied chemical. Conversely, the approach revealing the comprehensive metabolome of the biological system under investigation should be called metabolomics. Metabonomics is a further specialization of the omics approach, which is based on the systematic profiling of metabolite levels, but encompasses the systematic and temporal changes of the metabolome in whole organisms occurring in response to diet, lifestyle, environment, etc. 3

A multifactorial approach in characterizing geographical origin of Sicilian cherry tomatoes using 1H-NMR profiling

In this study, metabolomic analysis of chloroform extracts was performed to characterize cherry tomatoes (cv Naomi and Shiren) grown in different Sicilian areas, using 1H NMR spectroscopy coupled with multivariate statistical analysis. Principal components analysis showed clear discrimination between extracts of cherry tomatoes cultivated in two different seasons (winter and summer) and grown in three areas of Sicily (Gela, Licata, Pachino). In particular, carotenoids and phospholipids mainly were found to be more discriminating metabolites for both cultivars in summer and winter. In the present study, the simple separation only based on production area was found to be inadequate to distinguish the three groups of tomatoes. A clear separation among the different samples groups was obtained using a multifactorial approach not only based on the geographical origin classification, but considering also cultivar, year and seasonality.

Combined magnetic resonance imaging and high resolution spectroscopy approaches to study the fertilization effects on metabolome, morphology and yeast community of wine grape berries, cultivar Nero di Troia

Effects of fertilization practices, mineral (M) and organo-mineral (OM), on molecular composition of Nero di Troia cultivar grape berries was studied using conventional chemical analysis, Magnetic Resonance Imaging (MRI) and 1H NMR spectroscopy on intact berries and extracts, respectively, and through analysis of yeast species developed on grape skins. Plants vegetative status did not differ between the two fertilization practices, whereas some grape juice chemical characteristics differed in fertilized grapes. MRI provided information on grape berries morphology through weighted images depending on spin-spin (T2) and spin-lattice (T1) relaxation times. T1 values were the highest in OM grape berries. 1H NMR metabolic profile, combined with chemometric analysis, evidenced significant differences for some metabolites (valine, leucine, isoleucine, proline, and malic acid). Furthermore, higher frequency of yeasts genus Starmella sp., isolated from OM grape berries contributed to reinforcing the found results on the physiological response of wine grape Nero di Troia to fertilization.