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Semi-solid extrusion (SSE) 3D printing technology was utilized for the encapsulation of octreotide acetate (OCT) into 3D-printed oral dosage forms in ambient conditions. The inks and the OCT-loaded 3D-printed oral dosage forms were characterized by means of rheology, Fourier-transform infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR). In vitro studies demonstrated that the formulations released OCT in a controlled manner. The application of these formulations to Caco-2 cell monolayers revealed their capability to induce the transient opening of tight junctions in a reversible manner as evidenced by Transepithelial Resistance (TEER) measurements. Cellular assays (CCK-8 assay) demonstrated the viability of intestinal cells in the presence of these formulations. The in vitro transport studies across Caco-2 monolayers demonstrated the ability of these formulations to enhance the OCT uptake across the cell monolayer over time due to opening of the tight junctions.

Costic acid has been isolated from the plant Dittrichia viscosa and its efficacy against Varroa destructor, a parasite of Apis mellifera, the European honey bee, has been studied. Costic acid exhibited potent in vivo acaricidal activity against the parasite. Initial experiments showed that the compound is not toxic for human umbilical vein endothelial cells (HUVEC) at concentrations of up to 230 micromolar (μM), indicating that costic acid could be used as a safe, low-cost and efficient agent for controlling varroosis in honey bee colonies.

NMR is an emerging technology in the field of food analysis. Its combination with multivariate statistics and the application of multinuclear and multidimensional experiments has already established NMR as an important analytical tool for fingerprinting, quantification and compound identification in foods, and further increases its potential for becoming one of the main analytical approaches in this scientific area. The present article provides a solid overview of modern NMR applications in food analysis. Studies from the three main categories of studies, namely high resolution liquid state NMR spectroscopy, solid state CP-MAS/HR-MAS and low resolution (low field and MRI) are presented, and although covering heavily work after 2015, earlier key publications within the last 7–8 years are also mentioned. Basic concepts of NMR related to specific food analysis methodologies are briefly discussed when required. Finally, we tried to provide a more detailed discussion on field areas that NMR may be considered as an underutilized technology, such as high resolution NMR for monitoring food quality. Our goal is to provide the reader with the current knowledge about the most important aspects of NMR applications in various and diverse areas of food analysis.

One major disease of the pupae and the adult bee is the so-called Varroosis that is owing to the bee parasite Varroa destructor . It is an ectoparasite of bees, causing significant losses in the bee population needed for honey production as well as for pollination in agriculture. Costic acid is a sesquiterpene-carboxylic acid present in the plant Dittrichia viscosa . Recent studies by our group have shown that costic acid acts as acaricide against V. destructor . Oxalic acid is also an acaricide commonly used against varroa mites. In spite of its structural simplicity—it is the simplest bicarboxlic acid—it is equipotent to costic acid which consists of a trans -decalin system with three chiral centres. The basic goal of this project was to design and synthesize a hybrid entity, incorporating aspects of both oxalic acid and costic acid that would be more active than the parent compounds. This approach introduces a useful strategy for the preparation of congeners of bioactive compounds and proposes a structural framework for a new series of acaricidal agents.

NMR spectroscopy has become an indispensable tool for the metabolic profiling of foods and food products. In the present protocol, we report an analytical approach based on liquid-state NMR for the determination of polar and nonpolar metabolites in some common liquid (wine, spirits, juice) and solid (cheese, coffee, honey) foods. Although the diversity of foods precludes the use of a single protocol, with small modifications, the proposed methodologies can be adapted to a broader range of foodstuffs.

NMR spectroscopy has become an indispensable tool for the metabolic profiling of foods and food products. In the present protocol, we report an analytical approach based on liquid-state NMR for the determination of polar and nonpolar metabolites in some common liquid (wine, spirits, juice) and solid (cheese, coffee, honey) foods. Although the diversity of foods precludes the use of a single protocol, with small modifications, the proposed methodologies can be adapted to a broader range of foodstuffs.

A methodology based on 13C NMR spectroscopy was employed to detect and quantify fourteen mono-, di- and trisaccharide molecules in authentic Greek honey samples with no prior separation. Unambiguous assignment of 13C NMR chemical shifts has been achieved by means of two-dimensional NMR techniques using sugar model compounds. The quantitative 13C NMR method was rigorously validated (accuracy, linearity, range, limit of detection, etc.) using either single sugar molecules, or artificial mixtures of isoglucose (glucopyranose and fructose) and global mixtures of fourteen model compounds. Subsequent integration of appropriate signals in the 13C NMR spectra allowed the quantification of these compounds. The present methodology has been applied to authentic Greek honey samples and provided quantitative results for 28 sugar tautomers. The observed differentials in the content of these biomarkers amongst the various honey samples of different botanical origins are expected to form the basis for the development of a sensitive method that can be used to obtain valuable information about the authenticity of honey.

Dyslipidemia and impaired glucose metabolism are the main health issues of growing prevalence and significant high healthcare cost, requiring novel prevention and/or therapeutic approaches. Epidemiological and animal studies revealed that olive oil is an important dietary constituent, inducing normolipidemia. However, no studies have specifically investigated the polyphenol-rich water extract of olives (OLWPE), generated during olive oil production. In the present work, we initially examined the effect of OLPWE on animals’ metabolic parameters. Rats fed with a high-fat diet were treated with three different doses of OLPWE for 4 months. Additionally, bioavailability was explored. Afterwards, OLWPE’s metabolic effect was explored in humans. Healthy volunteers consumed microencapsulated OLWPE for 4 weeks, in a food matrix [one portion (30 g) of a meat product]. High-fat-fed rats developed a metabolic dysfunction, with increased LDL and insulin levels and decreased HDL; this syndrome was significantly impaired when treated with OLWPE. Treated rats had increased total plasma antioxidant capacity, while several phenolic compounds were detected in their blood. These findings were also verified in humans that consumed OLWPE, daily, for 4 weeks. Interestingly, in individuals with elements of cardio-metabolic risk, OLWPE consumption resulted in reduced glucose, insulin, total cholesterol, LDL and oxLDL levels. Our data clearly show that OLWPE can improve glucose and lipid profile, indicating its possible use in the design of functional food and/or therapeutic interventions.

A comprehensive summary of research work related to applications of NMR spectroscopy in combination with multivariate statistical analysis techniques for the analysis, quality control, and authentication of wine is presented. NMR spectroscopy is used to obtain the non-volatile metabolic profile and/or phenolic profile of wines, with the help of 2D NMR spectroscopy. Metabolomics is then used as an analytical tool to investigate the variability of the metabolic profile of wines due to a series of different factors involved during wine production, including terroir, pedoclimatic conditions, vintage, vineyard practices, wine-making, barrel maturation, and aging. The discriminating power of the NMR-obtained wine metabolome is utilized as a wholistic analytical approach in efforts to authenticate wine with respect to important economic attributes, such as cultivar, vintage, and geographical origin. Graphical abstract .

NMR spectroscopy is a powerful analytical tool for the identification and quantitative analysis of organic materials in a cultural heritage context. In this report, we present an analytical NMR protocol for the identification and semiquantification of egg yolk binders and mixed binding media that also contain a drying oil, namely linseed oil. The samples studied have been artificially and/or naturally aged in order to simulate the composition of organic materials in paintings. Analysis of the 1D and 2D NMR spectra showed that egg yolk can be identified even in binding media of considerable age via signals originating from cholesterol and/or cholesterol oxidation products present in the aged binding medium. Based on cholesterol-related and other lipid signals in the NMR spectra of egg yolk binders, a molecular marker (R/F) that suggests the presence of egg yolk in paint binders is proposed. Via this marker, the presence of egg yolk in the organic material obtained from an early 18th century Greek icon is confirmed, and this is further verified by 2D NMR spectroscopy. It is demonstrated that NMR molecular markers developed to estimate the hydrolysis/oxidation state of oil paintings are also suitable for the analysis of egg yolk and mixed medium (egg yolk–linseed oil) binders, indicating the generality of the NMR methodological approach in the analysis of organic materials in a cultural heritage context. Copyright © 2014 John Wiley & Sons, Ltd.

The use of LH3 (2-(β-naphthalideneamino)-2-hydroxymethyl-1-propanol) and aibH (2-amino-isobutyric acid) in 4f chemistry has led to the isolation of eight new isostructural lanthanide complexes. More specifically, the reaction of the corresponding lanthanide nitrate salt with LH3 and aibH in MeOH, under solvothermal conditions in the presence of NEt3, led to the isolation and characterization of seven complexes with the general formulae [LnIII7(OH)2(L′)9(aib)]·4MeOH (Ln = Gd, 1·4MeOH; Tb, 2·4MeOH; Dy, 3·4MeOH; Ho, 4·4MeOH; Er, 5·4MeOH; Tm, 6·4MeOH; Yb, 7·4MeOH L′ = the dianion of the Schiff base between naphthalene aldehyde and 2-amino-isobutyric acid). Furthermore, the isostructural YIII analogue, cluster [YIII7(OH)2(L′)9(aib)]·4MeOH (8·4MeOH), was synthesized in a similar manner to 1–7. The structure of all eight clusters describes a distorted [MIII6] octahedron which encapsulates a seventh MIII ion in an off-centre fashion. Dc magnetic susceptibility studies in the 5–300 K range for complexes 1–7 reveal the presence of dominant antiferromagnetic exchange interactions within the metallic clusters as evidenced by the negative Weiss constant, θ, while ac magnetic susceptibility measurements show temperature and frequency dependent out-of-phase signals for the [DyIII7] analogue (3·4MeOH), suggesting potential single molecule magnetism character. Furthermore, for complex 1, simulation of its dc magnetic susceptibility data yielded very weak antiferromagnetic interactions within the metallic centres. Solid-state emission studies for all 1–8 clusters display ligand-based emission, while extended 1D and 2D NMR studies for 8·4MeOH reveal that the species retain their structural integrity in solution. In addition, TGA measurements for 1, 3 and 7 revealed excellent thermal stability up to 340 °C for the clusters.

This chapter is devoted to applications of NMR in food analysis between January 2010 and June 2015, the term NMR encompassing a broad range of magnetic resonance applications, including spectroscopy, imaging and relaxation. The data included are arranged in subchapters according to food type (beverages, fats/oils fruits/vegetables, meat, dairy etc.), to help the reader locate relevant information.

Due to the neurotoxicity of organophosphate (OP) pesticides and nerve agents synthesized as military or terror agents, their safe destruction and disposal is of considerable current importance. A representative OP, trimethyl phosphate (TMP), was adsorbed onto NaX zeolite, two mesoporous modifications, and a low-silica X zeolite. The nucleophilic chemical reactions of TMP with the zeolites were investigated by solid-state 13C and 31P nuclear magnetic resonance (NMR) and the solvent extracts by 1H, 13C, and 31P NMR. Nucleophilic substitution and subsequent hydrolysis reaction schemes are proposed. All of the zeolites have similar TMP decomposition yields, supporting the hypothesis that slow or incomplete diffusion of TMP in the microporous zeolite regions limits TMP decomposition.

Two original art installations constructed from unsaturated polyester resins (UPR) and four different reference UPR products (before and after UVB aging) were analyzed by high-resolution 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Breaking strain studies were also conducted for the four UPR model products before and after different aging procedures (moisture, UVB exposure, melt/freeze). NMR analysis of the chemical composition of the UPR resin extracts showed they contain several low MW organic compounds and oligomers rich in polar -OH groups that play a significant role in the degradation behavior of the composite UPR materials. Statistical analysis of the NMR compositional data showed that styrene and benzaldehyde contents can be used to differentiate between fresh and aged UPR samples. The phthalate and propylene glycol unit speciation (esterified, primary or secondary -OH) of the extracts provided evidence that UPR resin C was used in the construction of the two art installations, and direct comparison of (1)H and (13)C NMR spectra verified this compositional similarity. UPR resin C was shown by both NMR and breaking strain studies to be the reference UPR most susceptible to degradation by different aging procedures, a characteristic attributed to the lower styrene content of resin C.

This review is a brief account on the application of a novel methodology to the quality control and authentication of extra-virgin olive oil. This methodology is based on the derivatization of the labile hydrogens of functional groups, such as hydroxyl and carboxyl groups, of olive oil constituents with the phosphorus reagent 2-chloro-4,4,5,5-tetramethyldioxaphospholane, and the use of the (31)P chemical shifts to identify the phosphitylated compounds. Various experimental aspects such as pertinent instrumentation, sample preparation, acquisition parameters and properties of the phosphorus reagent are reviewed. The strategy to assign the (31)P signals of the phosphitylated model compounds and olive oil constituents by employing 1D and 2D NMR experiments is presented. Finally, the capability of this technique to assess the quality and the genuineness of extra-virgin olive oil and to detect fraud is discussed.

In the current study, the heterogeneous reaction of NO2 with soot and biosoot surfaces was investigated in the dark and under illumination relevant to atmospheric conditions (J(NO2) = 0.012 s(-1)). A flat-flame burner was used for preparation and collection of soot samples from premixed flames of liquid fuels. The biofuels were prepared by mixing 20% v/v of (i) 1-butanol (CH3(CH2)3OH), (ii) methyl octanoate (CH3(CH2)6COOCH3), (iii) anhydrous diethyl carbonate (C2H5O)2CO and (iv) 2,5 dimethyl furan (CH3)2C4H2O additive compounds in conventional kerosene fuel (JetA-1). Experiments were performed at 293 K using a low-pressure flow tube reactor (P = 9 Torr) coupled to a quadrupole mass spectrometer. The initial and steady-state uptake coefficients, γ0 and γ(ss), respectively, as well as the surface coverage, N(s), were measured under dry and humid conditions. Furthermore, the branching ratios of the gas-phase products NO (∼80-100%) and HONO (20%) were determined. Soot from JetA-1/2,5-dimethyl furan was the most reactive [γ0 = (29.1 ± 5.8) × 10(-6), γ(ss)(dry) = (9.09 ± 1.82) × 10(-7) and γ(ss)(5.5%RH) = (14.0 ± 2.8)(-7)] while soot from JetA-1/1-butanol [γ0 = (2.72 ± 0.544) × 10(-6), γ(ss)(dry) = (4.57 ± 0.914) × 10(-7), and γ(ss)(5.5%RH) = (3.64 ± 0.728) × 10(-7)] and JetA-1/diethyl carbonate [γ0 = (2.99 ± 0.598) × 10(-6), γ(ss)(dry) = (3.99 ± 0.798) × 10(-7), and γ(ss)(5.5%RH) = (4.80 ± 0.960) × 10(-7)] were less reactive. To correlate the chemical reactivity with the physicochemical properties of the soot samples, their chemical composition was analyzed employing Raman spectroscopy, NMR, and high-performance liquid chromatography. In addition, the Brunauer-Emmett-Teller adsorption isotherms and the particle size distributions were determined employing a Quantachrome Nova 2200e gas sorption analyzer. The analysis of the results showed that factors such as (i) soot mass collection rate, (ii) porosity of the particles formed, (iii) aromatic fraction, and (iv) pre-existence of nitro-containing species in soot samples (formed during the combustion process) can be used as indicators of soot reactivity with NO2.

The solution properties and the micellization behavior of double hydrophilic diblock copolymers depend on the degree of ionization of the pH-tunable block. This is investigated by dynamic light scattering and 1H NMR spectroscopy in aqueous solutions of diblock copolymers comprising a neutral hydrophilic poly(hexa(ethylene glycol) methacrylate), PHEGMA, block and an ionizable poly(2-(diethylamino)ethyl methacrylate), PDEAEMA, block. At low pH the copolymer is in its unimer state due to the hydrophilicity of the protonated tertiary amine units, while an increase of the solution pH results in the deprotonation of the amine residues, which become hydrophobic, and leads to the formation of micelles consisting of a PDEAEMA core and a PHEGMA corona. The critical degree of ionization for chain aggregation and micelle formation is determined. It is found that the polymer exists as unimers in the aqueous solution for as low as 30% protonated amine groups, whereas for 20% degree of ionization a slight increase in po...

Nuclear magnetic resonance spectroscopy is applied to the study of aged binding media used in paintings, namely linseed oil, egg tempera and an acrylic medium. High resolution 1D and 2D NMR experiments establish the state of hydrolysis and oxidation of the linseed and egg tempera binders after five years of aging, by determining several markers sensitive to the hydrolytic and oxidative processes of the binder lipid fraction. The composition of the acrylic binder co-polymer is determined by 2D NMR spectroscopy, while the identification of a surfactant, poly(ethylene glycol), found in greater amounts in aged acrylic medium, is reported.

In an attempt to identify the structure of a sesquiterpene from Cistus creticus ssp. creticus proposed in the literature as 1,1,4a,6-tetramethyl-5-methylene-1,2,3,4,4alpha,5,8,8alpha-octahydronaphthalene, the synthesis of its cis isomer 2 was carried out in 11 steps and 9.5% yield. Comparison of the spectra of 2 and those reported earlier for the synthetic trans isomer 1 with the spectral profile of the isolated natural product indicated that the latter was not compatible with either 1 or 2. The correct structure was assigned, by detailed spectroscopic analysis of the natural product, as 6-isopropenyl-4,4a-dimethyl-1,2,3,4,4a,5,6,7-octahydronaphthalene (3).

Nuclear magnetic resonance spectroscopy is proposed as an efficient analytical tool in the study of painted artworks. The binding medium from two original oil paintings, dated from the early 20th and the late 17th century, was studied via high-resolution 1D and 2D NMR, establishing the advanced state of hydrolysis and oxidation of the oil paint. Studies of the solvent-extractable component from model samples of various drying oils, raw oil paints, and aged oil paints allowed the definition of several markers based on the integral ratios of various chemical species present in the 1H and 13C NMR spectra. These markers are sensitive to hydrolytic and oxidative processes that reflect the extent of aging in oil paintings. The rapidity, simplicity, and nondestructive nature of the proposed analytical NMR methodology represents a great advantage, since the usually minute sample quantities available from original artwork can be subsequently analyzed further by other analytical techniques, if necessary.

Diacylglycerol isomers and free acidity were determined for five extra virgin olive oils of different initial acidities by employing a facile (31)P NMR methodology as a function of storage time and storage conditions. The kinetic treatment of the hydrolysis of triacylglycerols (TGs) and the isomerization of 1,2-diacylglycerols (1,2-DGs) to 1,3-diacylglycerols (1,3-DGs) during storage of 18 months at ambient temperature in the dark and light and at 5 degrees C in the dark showed that the isomerization is strongly dependent on the rate of the TGs hydrolysis, the initial free acidity (H(0)) of the virgin olive oil samples, and storage conditions. Although the time-evolution of the diacylglycerols (DGs) depends on the TGs hydrolysis, the ratio D of the concentration of 1,2-DGs to the total amount of DGs was found to be independent of this factor. From the kinetic expression of the ratio D, a quantitative measure was formulated that allows the estimation of the storage time or age of virgin olive oils. Application of this quantitative measure to several olive oil samples of known and unknown storage history resulted in a very good agreement with respect to the actual storage time for up to 10-12 months of storage. For a longer storage period, where the isomerization of DGs is close to its equilibrium state, the calculated age index is only indicative.

A combination of (1)H NMR and (31)P NMR spectroscopy and multivariate statistical analysis was used to classify 192 samples from 13 types of vegetable oils, namely, hazelnut, sunflower, corn, soybean, sesame, walnut, rapeseed, almond, palm, groundnut, safflower, coconut, and virgin olive oils from various regions of Greece. 1,2-Diglycerides, 1,3-diglycerides, the ratio of 1,2-diglycerides to total diglycerides, acidity, iodine value, and fatty acid composition determined upon analysis of the respective (1)H NMR and (31)P NMR spectra were selected as variables to establish a classification/prediction model by employing discriminant analysis. This model, obtained from the training set of 128 samples, resulted in a significant discrimination among the different classes of oils, whereas 100% of correct validated assignments for 64 samples were obtained. Different artificial mixtures of olive-hazelnut, olive-corn, olive-sunflower, and olive-soybean oils were prepared and analyzed by (1)H NMR and (31)P NMR spectroscopy. Subsequent discriminant analysis of the data allowed detection of adulteration as low as 5% w/w, provided that fresh virgin olive oil samples were used, as reflected by their high 1,2-diglycerides to total diglycerides ratio (D > or = 0.90).

In this study, the diglyceride contents of 96 samples of virgin olive oils from the regions of Crete, Lesvos, Messinia, Pilion, Zakynthos, Halkidiki, and Ilia, 15 samples of commercial extra virgin and pure olive oils, and 3 samples each of refined olive oils and pomace oils were determined by a facile method introduced in a previous publication. This method is based on the phosphitylation of the free hydroxyls of the diglycerides with 2-chloro-4,4,5,5-tetramethyldioxaphospholane and the integration of the appropriate peaks in the (31)P NMR spectra. This preliminary study showed interesting trends in the diglyceride content of the virgin olive oils from the various regions of Greece that can be used as simple criteria to assess the olive oil characteristics. Analysis of variance has been carried out for the diglyceride content of each region in an attempt to detect possible differences in the diglyceride levels among the various regions. Finally, the relationship between the ratio of 1,2-diglycerides to the total amount of diglycerides and the total amount of diglycerides has been used to monitor the quality of virgin olive oils, commercial olive oils, refined olive oils, and pomace oils.

NMR spectroscopy is a powerful analytical tool for the identification and quantitative analysis of organic materials in a cultural heritage context. In this report, we present an analytical NMR protocol for the identification and semiquantification of egg yolk binders and mixed binding media that also contain a drying oil, namely linseed oil. The samples studied have been artificially and/or naturally aged in order to simulate the composition of organic materials in paintings. Analysis of the 1D and 2D NMR spectra showed that egg yolk can be identified even in binding media of considerable age via signals originating from cholesterol and/or cholesterol oxidation products present in the aged binding medium. Based on cholesterol-related and other lipid signals in the NMR spectra of egg yolk binders, a molecular marker (R/F) that suggests the presence of egg yolk in paint binders is proposed. Via this marker, the presence of egg yolk in the organic material obtained from an early 18th century Greek icon is confirmed, and this is further verified by 2D NMR spectroscopy. It is demonstrated that NMR molecular markers developed to estimate the hydrolysis/oxidation state of oil paintings are also suitable for the analysis of egg yolk and mixed medium (egg yolk-linseed oil) binders, indicating the generality of the NMR methodological approach in the analysis of organic materials in a cultural heritage context.

Quantitative 31P-NMR spectroscopy is used to measure the hydroxyl and carboxyl content of some polyester resins (short- and long-oil alkyds, polyols, polyesters) through derivatization of the —OH protons with 2-chloro-4,4,5,5-tetramethyldioxaphospholane I. This methodology is shown to be superior to titration methods, since it can (a) discriminate between primary and secondary hydroxyl groups, (b) identify individual alcohols and acids present, (c) measure the amount of free fatty acids in oil-modified alkyds, and (d) provide lower limits for the number-averaged molecular weight of the resins and exact values for linear polyesters. A major advantage of the technique is that the NMR measurements are made on unmodified resins in their final product form supplied by the manufacturer. The information obtained is important for the characterization of the alkyd resins and affects drastically their physical properties and performance as products. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1635–1642, 2002

Phosphitylation of the free hydroxyl and carboxyl groups of a series of polyphenol-containing olive oil model compounds with 2-chloro-4,4,5,5-tetramethyl-dioxaphospholane allows their classification on the basis of 31P NMR chemical shifts. Unambiguous assignment of the 31P NMR chemical shifts of the dihydroxy- and polyhydroxy-phenols has been achieved by employing one and two-dimensional NMR techniques. Furthermore, integration of the appropriate signals of the hydroxyl derivatives in the corresponding 31P NMR spectra allows the quantification of these compounds. This study forms the basis for the development of a novel and sensitive method that can be used to obtain valuable information about polyphenols that are present in olive oils.

Carbon dots (C-dots) represent a new class of carbon-based materials that were discovered recently and have drawn the interest of the scientific community, particularly because of their attractive optical properties and their potential as fluorescent sensors. Investigation of the chemical structure of C-dots is extremely important for correlating the surface modifier composition with C-dot optical properties and allow for structure–properties fine tuning. In this article, we report the structural analysis of the surface modifiers of three different types of C-dot nanoparticles (Cwax, Cws, and Csalt) by use of 1D- and 2D-high-resolution NMR spectroscopy in solution. We unambiguously verify that the structure of the modifier chains remains chemically unchanged during the passivation procedure, and confirm the covalent attachment of the modifiers to the nanoparticle core, which contributes no signal to the solution-state NMR spectra. To our knowledge, this is the first study confirming the full structural assignment of C-dot organic surface modifiers by use of solution NMR spectroscopy.

In recent years HR-MAS 1H NMR spectroscopy has proven to be a useful tool for the rapid determination of the metabolic profile of several solid and semisolid foods, such as fruits and vegetables, cheese and meat. Olive leaves are today recognized as direct sources of bioactive compounds and natural antioxidants (flavonoids, secoiridoids) suitable as food additives, and their extracts form the basis of beauty care products and pharmaceutical supplements. Thus, olive leaves are emerging as a new and potentially important product for olive tree growing regions. In this report we present the application of 1H and 13C HR-MAS 1D and 2D NMR spectroscopy for the characterization and analysis of triterpenoids in solid olive leaves using CDCl3 for locking. Our data show that HR-MAS NMR spectroscopy is a powerful tool for the direct compositional analysis of triterpenoids in olive leaves without the need for any sample pretreatment or solvent extraction steps.

13 C NMR spectroscopy is used to study the local segmental dynamics in the bulk of biodegradable poly(4-hydroxybutyrate) and a random copolymer of 3-hydroxybutyrate and 4-hydroxybutyrate that contained 18% 4-hydroxybutyrate units. The crystalline phase of the copolymer is shown by solid-state 13 C NMR to be comprised of 3HB units, in accord with reports based on X-ray diffraction. 13 C relaxation measurements indicate that the local dynamics in the amorphous phase are of different time scale for the two different types of monomer units in the copolymer. Furthermore, the segmental motions of the 4-hydroxybutyrate units are found to be slower in the copolymer than in the homopolymer.

Variable-temperature 13C NMR spin-lattice relaxation times (T1) and Nuclear Overhauser Enhancements (NOE) at two magnetic fields have been used to study the dynamics of the amorphous part of a semicrystalline sample (33% of crystallinity) of poly(β-hydroxyoctanoate) (PHO). The interpretation of the relaxation data of the backbone carbons was made by employing a number of motional models. Among these, the DLM model offered the best interpretation of the relaxation data in terms of conformational transitions and librational motions of the backbone CH vectors, and proved to be superior to unimodal distribution functions. The interpretation of temperature- and frequency-dependent T1 and NOE data of the carbon nuclei in the n-pentyl side chain was made by employing a newly developed composite spectral density function for multiple internal CC bond rotations of restricted amplitude and chain segmental motion. The temperature dependence of the linewidths of the various protonated carbon resonances of PHO has been discussed in terms of the semicrystalline character of this polymer. © 1995 John Wiley & Sons, Inc.

It is well recognized in recent years that NMR spectroscopy has become an indispensable tool in the hands of research scientists dealing with the quality control and authentication of foods. This chapter copes with a variety of NMR techniques and their applications to food science and food analysis. Short introductions of these techniques are given in this account, since their theoretical and experimental aspects are very well described in several introductory and advanced books. This chapter is prepared by grouping the most useful NMR experiments and the different information that can be extracted from each kind of experiment. In addition, when possible, a short note about the required instrumentation and pertinent sample preparation accompanies the description of each NMR technique. Following this brief presentation, more recent developments of NMR methodologies used preferentially in solid foods are described in relation to new, challenging problems encountered in food science. Finally, selected applications to food science are covered from the NMR point of view rather than by taking into account each foodstuff individually.

Chain segmental motion and side-chain internal rotation of poly(1-naphthylmethyl acrylate) in dilute solution have been studied by employing the l3C nuclear magnetic relaxation technique. Correlation times and diffusion constants were determined through dynamic modeling of the various modes of reorientation occurring in this polymer as a function of temperature and solvent viscosity. Local segmental motion and naphthyl internal rotation appear to follow Kramers' theory, whereas the correlation time for the side-chain methylene internal motion scales as 9'3.55, instead of the first power dependence predicted by Kramers' theory. The potential energy heights extracted from these measurements were found to be 11,21, and 5.5 kJ mol-' for segmental motion, naphthyl restricted internal rotation, and methylene restricted internal rotation, respectively. Furthermore, on the basis of our data some general conclusions were drawn regarding solvent effects on the expected photophysical behavior of poly(1-naphthylalkyl acry1ate)s.