Search

International audience; 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.

The chemical analysis that is frequently employed for the evaluation of the freshness of fish includes (i) the quantification of trimethylamine (TMA) and (ii) the estimation of the K-Index, based on the ratio between the concentrations of adenosine triphosphate (ATP) and its breakdown products. TMA is quantified using a colorimetric reference method (AOAC), while the K-Index is usually determined by HPLC. The present work proposes a method for the above freshness biomarkers based on HR 1H-NMR as an alternative method able to assess both indexes simultaneously on aqueous fish extracts. To validate the proposed 1H-NMR method, a large set of validation checks has been addressed, such as accuracy, precision, specificity, limits of detection, linearity, and range of linearity and quantification according to EuroChem guidelines. The results show that the methodology satisfies all the validation requirements at the same level as the most frequently used methods, with the advantage of being faster and more repeatable, avoiding the use of solvents, such as toluene and formaldehyde, or dangerous reagents such as picric acid.

This study aimed to assess the astaxanthin (Ax) accumulation in hepatocytes isolated from farmed Atlantic salmon fed different diets (rich marine, poor, poor with marine phospholipids (MPL) and poor with docosahexaenoic acid (DHA)). Nuclear magnetic resonance (NMR) spectroscopy was used for the Ax detection and quantification. The use of the 13C-enriched Ax allowed the assessment of short-time Ax metabolism. The substitution of fish oil and meal in fish feed on plant analogs and the addition of MPL caused further catabolism and decrease of Ax accumulation in hepatocytes from 17 to about 6 mg/kg or to almost zero in the case of DHA addition. Signals assignment of the native and 13C-enriched astaxanthin in acetone were performed using 1D and 2D NMR spectra. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Background Plant viral infections induce changes in metabolic components in the host plant, with potential effects on compositional, organoleptic and storability features of agricultural products. Identification of modulated metabolites may provide clues concerning pathways implementing responses in plant-pathogen interactions. A time course study of metabolic fingerprinting of onion yellow dwarf virus (OYDV)-infected versus healthy 'Rossa di Tropea' onion bulbs was performed using proton high-resolution magic angle spinning nuclear magnetic resonance (1 H HR-MAS NMR) and ultra-performance liquid chromatography (UPLC), providing an overview of the metabolic state of the bulb in response to OYDV infection during storage. Results Metabolites accumulated/depleted upon infection were identified, belonging to flavonoid, saccharide, amino acid and organic acid classes. A decrease in quercetin glucosides content and antioxidant activity was observed in infected bulbs; some amino acids (Arg, Asn, Phe, Val) accumulated, while others were depleted (Leu); for some metabolites, a bimodal time-course was observed during storage (Glc, Lys). Virus interference on metabolic pathways, and the effects of the metabolic shift on edible product storability, organoleptic and nutritional quality were discussed. Conclusions OYDV infection induces a metabolic shift in 'Rossa di Tropea' onion during bulb storage, involving several pathways and affecting storability and organoleptic and nutritional quality of bulbs at marketable stage. © 2020 Society of Chemical Industry.

The evaluation of fish freshness can be performed using chemical, sensory and physical methods. Besides sensory methods, several instrumental techniques have been applied with the objective of replacing sensory assessment. The aim of this study was to set up and test objective physical methods mainly based on computer vision system (CVS) to assess red mullet (Mullus barbatus) freshness evolution during 10 days of storage, at two different storage temperatures (0 and 4 °C). To check the effectiveness of the purposed physical methods, CVS features (loss in the epidermis pigmentation, development of gill mucus and eye concavity index) and firmness have been compared with chemical trimethylamine content and sensory (QIM) attribute scores. As expected, fish degradation was faster at the higher temperature. Instrumental texture evaluation of fish by penetration test enabled to detect distinctive firmness changes due to onset and resolution of rigor mortis, and the successive tenderization phenomenon. Among CVS parameters, the epidermis pigmentation loss, and particularly the eye shape modification (eye concavity index) evidenced a high sensibility for the estimation of fresh red mullet quality loss, as a function of the two different storage conditions, and a good agreement with trimethylamine content and QIM response evolution.

In this study, metabolomic analysis of chloroform extracts was performed to characterize cherry tomatoes (cv Naomi and Shiren) grown in different Sicilian areas, using 1 H 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.

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.

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 1H–1H TOCSY and 1H–13С 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.

Nuclear magnetic resonance spectroscopy was employed to obtain information about the changes occurring in Bogue (Boops boops) fish during storage. For this purpose, (1)H-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.

Magnetic resonance imaging (MRI) has been used to study the variations of internal structure and chemical–physical characteristics of cherry tomatoes (Lycopersicon esculentum cv. Shiren), one the most economically valuable horticultural crops, in different harvesting seasons. In particular, the study focused on PGI (Protected Geographical Indication) Pachino cherry tomatoes, characterised by taste and nutritional value, notably in the winter production, amounting about 500 ton/year. Spin–spin and spin–lattice relaxation times, T2 and T1 respectively, determined on whole fruit, provided useful data highlighting variations among samples according to the season (winter, spring and summer). MRI images evidenced differences among cellular tissues such as pericarp and endocarp, through variations of: (1) T2 and T1 measures and water tumbling and diffusion motion, (2) thicknesses of different morphological zones, (3) qualitative characteristics of the tissue covering placental cavities where seeds are contained. Results of variance analysis (ANOVA) showed that physical parameters, as the transverse and longitudinal relaxation times, T2 and T1, measured in the morphological tissues of vegetables are excellent variables highlighting their differences in different seasons. This innovative non-destructive technique in food science has great potential in fruit quality assessment.

Arsenic (As) is a highly toxic element and its presence in food is a matter of concern for the well-being of both animals and humans. Arsenic-contaminated groundwater is used in agriculture to irrigate crops for food and animal consumption with a potential contamination of the food chain. The purpose of this study was the evaluation of arsenic effect on radish tuber (Raphanus sativus L.). Experimental plots with sandy and clay-loamy soil were cultivated with radish and treated with three different concentrations of As water solution: 19, 44 and 104 µg/L. Magnetic resonance imaging was used to visualize the tuber structural changes, and the content of elements and the As amount were evaluated by inductively coupled plasma atomic emission spectroscopy. The data obtained demonstrate that As contamination in radish tuber is underlined with the dual approach. PRACTICAL APPLICATIONS The scope of this research is the evaluation of the effects on the toxicology and the morphology because of the arsenic (As) uptake by edible plants. The focus is on the contamination of the plant, which has implications for food safety and human health. The results obtained by magnetic resonance imaging and inductively coupled plasma atomic emission spectroscopy show that several changes of the internal structure occurred and that some parameters can be used as indicators of the As contamination in food.

The chemical composition of coffee has been widely investigated, focusing the attention both on main components and trace compounds. Most of these studies have been performed by using liquid and gas chromatography, eventually combined with mass spectroscometry. These techniques, although straight and effective, are time demanding due to the sample pretreatments. Here, we propose high-resolution-magic-angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR), a system capable of acquiring highly resolved NMR spectra of gel-like and suspension samples. This approach allowed us to determine the chemical composition of coarsely ground coffee beans of two varieties: Arabica and Robusta. Variation of the concentration of relevant species was monitored as a function of roasting temperature, from green beans to completely roasted. The HR-MAS NMR tool demonstrated to be very powerful for quick chemical composition determination, opening up possibilities for novel applications of this approach in food quality control. PRACTICAL APPLICATIONS Food quality control needs novel and press-button applications. High-resolution-magic-angle spinning nuclear magnetic resonance contains such requirements, since it can analyze suspension and gel-like samples, providing a chemical characterization with minor, or, in most cases, no chemical and physical pretreatment operations. The application proposed here concerns the examination of relevant molecules in coffee beans as a function of the roasting temperature. This can be used for a quality check of the final product, and such approach has a general suitability, being functional for almost all foodstuff, fresh and transformed.

Multifarious applications of NMR (high-resolution NMR in liquid-state and in semi-solid matrices, low-field NMR relaxometry, and NMR-imaging) in the analysis of food components and entire food samples are described using examples of different food matrices and different problems related to food safety, traceability, geographical and botanical origin, farming methods, food processing, maturation and ageing, etc. Althoug NMR has not yet been recognized as an official methodology for the food control the numerous applications of NMR reported in the literature show the potenziality of this methodology also as an approach complementary to the other recognized conventional methodologies.

Nuclear Magnetic Resonance (NMR) methodologies offer a comprehensive characterization of foodstuff owing to the possibility to study a sample from different points of view including structural, compositional, functional, morphological etc. aspects. High resolution NMR spectroscopy applied to semi-solid food samples or to extracts in solution is used to determine the foodstuff composition. Here, some features of high resolution NMR methodologies related to food analysis such as quantitative analysis, chemometrics, and use of databases are included. Other NMR methodologies such as relaxometry and imaging described in this chapter give precious information regarding the morphology and texture of intact food samples.