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Nuclear Magnetic Resonance (NMR) relaxometry is widely used for food products characterization. In order to exploit the full potential of the relaxation methods one can look at magnetic field dependence of spin-lattice relaxation. Analysis of relaxation dispersion characteristics of food systems may complement knowledge about composition and dynamics of their constituents, in particular, of water. In this article, we review the basic principles as well as recent applications of field-cycling NMR relaxometry in different food systems. The inter- and intra-molecular interactions modulated by molecular dynamics can be efficiently studied with NMR relaxometry. This method can be exploited for discrimination of liquids, determination of diffusion coefficient or paramagnetic ion concentration, observation of crystallization/solidification processes. The technique has already proven to be helpful to investigate changes occurring in food products due to different processing techniques and to detect food adulteration. FFC benchtop instruments represent a new frontier in food studies. [Display omitted] • NMR relaxometry is a powerful tool to characterize food products. • Principle of field-variable relaxometry and key advantages over conventional relaxometry is presented. • This review comprises an overview of the large spectrum of food-related applications of field-variable NMR relaxometry. [ABSTRACT FROM AUTHOR]

Abstract: Recent progresses of NMR spectroscopy to the study of liquid crystals and related ordered systems are surveyed. Particular attention will be devoted to review suitably tailored NMR experiments and their applications on those systems (e.g. biaxial nematics, chiral smectics, V shaped mesogens, liquid crystalline elastomers) which are presently subject of active and innovative research. [Copyright &y& Elsevier]

Abstract: For the first time new type of liquid single crystal elastomers forming the chiral smectic A* (SmA*) phase has been prepared using chiral lactic acid derivative as a co-monomer. The synthesis and the basic characterization of the ferroelectric liquid crystalline co-monomer based on differential scanning calorimetry and small/wide-angle X-ray scattering are reported and discussed. The monomer possesses the paraelectric SmA* and the ferroelectric SmC* phases over a broad temperature range. The preparation of new smectic liquid crystalline elastomers together with characterization of their mesomorphic and structural properties is also reported. New elastomers possess the orthogonal paraelectric SmA* phase over 50 K broad temperature range. [Copyright &y& Elsevier]

Abstract: Photoactive materials based on azobenzene derivatives exhibit interesting properties related to the reversible photo-isomerisation between the trans and cis isomers of the azo-compound. In this work we report the preparation and physical–chemical characterization of Liquid Single Crystal Elastomers (LSCEs) containing azobenzene derivative side-chain mesogens as co-monomer. The interplay between the orientational ordering and mechanical response in the nematic phase is investigated by thermomechanical measurements as well as by deuteron NMR spectroscopy. We demonstrate that local nematic order can be reliably probed in azo-LSCEs using low molar mass deuterated cyanobiphenyl nematogen in low concentrations. No phase separation of the dopant is observed. The nematoelastic coupling between the effective sample deformation and average nematic order parameter is present over a wide temperature range even in the systems with relatively large heterogeneity of the nematic order and misaligned nematic domains. [Copyright &y& Elsevier]

A new approach to analyze 2H spin-lattice relaxation times in tilted smectic phases in terms of dynamic parameters for individual molecular and internal motions is reported. Such analysis, commonly applied to uniaxial phases, could not be extended so far to chiral smectic phases for both experimental and theoretical reasons. These problems have been here overcome neglecting the dependence of spectral densities on the azimuthal angle φ, and adopting a global target approach. In this way, the existing diffusional models can be used to determine dynamic parameters in chiral smectic C phases. An application to the ferroelectric mesogen 8BEF5 is reported. [Copyright &y& Elsevier]

The dynamics of a chiral polymorphic liquid crystal smectogen (8BEF5), partially deuterated on the aromatic core and on the chiral chain, has been investigated in its smectic A and C* phases. The 2H T1Q and T1Z spin–lattice relaxation times, and, consequently, the spectral densities J1(ω0) and J2(2ω0) have been determined for the aromatic as well as methylene deuterons of the chiral chain closer to the aromatic core. The interpretation of the relaxation behaviour has been carried out by means of the available motional models in the SmA phase. Contrary to what is usually observed for other mesogens, in the case of 8BEF5 the internal rotations are much better described by the strong collision model rather than by the small step rotational diffusion one. [Copyright &y& Elsevier]

Abstract Bimesogenic liquid crystal elastomers, composed with controlled concentrations of two mesogenic constituents, specifically a nematogen and a smectogen, exhibit either enhanced nematic or smectic structure. Here we present a thorough examination of thermomechanical and elastic properties of such a system at high crosslinking density, with ensuing disordered smectic structure which prevents the observation of smectic-nematic phase transition by means of thermomechanical response measurements. Yet, the onset of local smectic order is clearly observable in stress-strain measurements via an anomaly in the elastic modulus. Breakdown of the local smectic structure is detected at higher mechanical loads. Bimesogen composition – temperature phase diagram is as well constructed, consistent with the one obtained by complementary experimental techniques. Stress-strain temperature dependence measurements can thus serve as efficient and simple phase diagram characterization method that is able to detect formation of smectic clusters in strongly crosslinked and thus highly disordered smecto-nematic liquid crystal elastomers. Graphical abstract Image 1 Highlights • Strongly crosslinked bimesogenic liquid crystal elastomers with enhanced nematic (N) or smectic A (SmA) structure. • Investigation of thermomechanical and elastic properties. • No SmA-N phase transition seen by thermomechanical measurements due to high crosslinking density. • All phase transitions can be identified with stress-strain studies, as well as the stress-induced SmA-N phase transition. • Simple approach for determination of bimesogen concentration – temperature – external mechanical stress phase diagram. [ABSTRACT FROM AUTHOR]

This study analyzed the effect of low sulfur dioxide concentrations on the chromatic properties, phytochemical composition and antioxidant activity of Aglianico red wines with respect to wines produced from conventional winemaking. We determined the phytochemical composition by spectrophotometric methods and HPLC-DAD analysis and the in vitro antioxidant activity of different wine samples by the ORAC assay. The main important classes of fluorophore molecules in red wine were identified by Front-Face fluorescence spectroscopy, and the emission intensity trend was investigated at various sulfur dioxide concentrations. Lastly, we tested the effects of both conventional and low sulfite wines on ex vivo human erythrocytes under oxidative stimulus by the cellular antioxidant activity (CAA) assay and the hemolysis test. The addition of sulfur dioxide, which has well-known side effects, increased the content of certain bioactive components but did not raise the erythrocyte antioxidant capacity. [ABSTRACT FROM AUTHOR]

Dry and fresh apples have been studied monitoring their polyphenolic profiles through 1 H NMR, antioxidant capacity and total polyphenol content. Six ancient and underutilized apple varieties (Mantovana, Mora, Nesta, Cipolla, Ruggina, Sassola) and a commercial one (Golden Delicious) were dried with an air-drying system at 45 °C for 19 h. Although some of their polyphenol constituents were lost during drying, the antioxidant capacity of some apple varieties remained higher compared to Golden Delicious. This result is very important for ancient and underutilized varieties that are not consumed on large scale as fresh product since they have low attractiveness, due to their ugly appearance. Combining quantitative NMR spectroscopy with principal component analysis we have identified and quantified several polyphenols (such as catechin, epicathechin, and chlorogenic acid) that are important to establish the nutraceutical value of the different investigated apple varieties. [ABSTRACT FROM AUTHOR]

The fermentation of Triticum dicoccum with sourdough enhances the nutritional aspects of the final product by the enrichment of several compounds with potential medical and biological activity, hence, could improve the health of consumers. This study analyzed the chemical composition of fermented spelt flour from Garfagnana (Province of Lucca, Tuscany) by 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy and its in vitro antioxidant properties by FRAP and DPPH tests. Beyond this, the ex vivo CAA-RBC assay determined the cellular antioxidant activity on human erythrocytes under oxidative condition. Carbohydrate reduction was observed, while amino acids, organic acids and aromatic compounds with potential antioxidant activity increased during the fermentation time. Moreover, both in vitro and ex vivo outcomes showed an improved antioxidant profile. As a possible industrial application, the fermentation process adopted in this research could be reproduced on a large scale for the commercialization of the products by the food industry. • The chemical composition of fermented spelt flour was studied by 1H NMR spectroscopy. • Bioactive compounds were identified and quantified at different fermentation times. • In vitro and ex vivo assays showed a significant raise in total polyphenols. • A good antioxidant capacity was detected by FRAP and DPPH assays. • CAA-RBC showed an increased antioxidant activity during the fermentation time. [ABSTRACT FROM AUTHOR]