Zero-field nuclear magnetic resonance of chemically exchanging systems.

Zero- to ultralow-field (ZULF) nuclear magnetic resonance (NMR) is an emerging tool for precision chemical analysis. In this work, we study dynamic processes and investigate the influence of chemical exchange on ZULF NMR J-spectra. We develop a computational approach that allows quantitative calculation of J-spectra in the presence of chemical exchange and apply it to study aqueous solutions of [15N]ammonium (15N[Formula: see text]) as a model system. We show that pH-dependent chemical exchange substantially affects the J-spectra and, in some cases, can lead to degradation and complete disappearance of the spectral features. To demonstrate potential applications of ZULF NMR for chemistry and biomedicine, we show a ZULF NMR spectrum of [2-13C]pyruvic acid hyperpolarized via dissolution dynamic nuclear polarization (dDNP). We foresee applications of affordable and scalable ZULF NMR coupled with hyperpolarization to study chemical exchange phenomena in vivo and in situations where high-field NMR detection is not possible to implement

Mathematical Modeling and Use of Magnetic Resonance Imaging (MRI) for Oil Migration in Chocolate Confectionery Systems

Oil migration is a common problem in chocolate confectionery products leading to quality defects, particularly fat bloom. Several factors such as contact area, ratio of the two fat phases, type of the fat, solid fat content, presence of non-fat solid particles, particle size, viscosity, structure, concentration gradient of triacylglycerols (TAGs), and storage temperature have all effect on migration rate. Mechanism of oil migration has still not been clearly understood, but possible mechanisms have been suggested and studied in the literature. Diffusion mechanism was demonstrated and modeled in many studies. Although there are so many methods to monitor and quantify migration, magnetic resonance imaging (MRI) is among the most promising techniques as being non-destructive. This review covers the literature related to basics of migration, mechanisms, and monitoring and modeling migration in chocolate through MRI and also includes a brief description about chocolate, chocolate processing, and fundamental concepts in MRI

Production of hazelnut skin fibres and utilisation in a model bakery product

Microfluidisation was used as a potential method for the production of fibrous structure from hazelnut skin (HS), and which was evaluated as an ingredient in cake as model bakery product. More specifically, effects of different amounts of microfluidised HS on rheological behaviour of cake batter and quality parameters (texture and colour) and storage characteristics of cake products were evaluated. Furthermore, performance of microfluidised HS was compared with conventionally milled HS and cacao powder for comparison purpose. The entangled structures of microfluidised HS resulted in much higher consistency index, yield stress and viscoelastic moduli values in batter samples than conventionally milled hazelnut skin. Highly shredded fibrous structure of microfluidised HS provided gluten-like strength and elasticity to cake samples resulting in higher springiness and firmness values. Darker crumb colour of the cake samples was caused by the homogenous distribution of fibrous microfluidised HS. Detailed staling analysis through X-ray and Fourier transform infrared measurements showed that microfluidised HS containing cake samples had lower retrogradation and staling tendency due to their lower starch content, and higher water holding ability. Findings of this study showed that microfluidised HS could be potentially utilised as an ingredient in bakery products

Development of pH Sensitive Alginate/Gum Tragacanth Based Hydrogels for Oral Insulin Delivery

Insulin entrapped alginate-gum tragacanth (ALG-GT) hydrogels at different ALG replacement ratios (100, 75, 50, 25) were prepared through an ionotropic gelation method, followed by chitosan (CH) polyelectrolyte complexation. A mild gelation process without the use of harsh chemicals was proposed to improve insulin efficiency. Retention of almost the full amount of entrapped insulin in a simulated gastric environment and sustained insulin release in simulated intestinal buffer indicated the pH sensitivity of the gels. Insulin release from hydrogels with different formulations showed significant differences (p < 0.05). Time domain (TD) NMR relaxometry experiments also showed the differences for different formulations, and the presence of CH revealed that ALG-GT gel formulation could be used as an oral insulin carrier at optimum concentrations. The hydrogels formulated from biodegradable, biocompatible, and nontoxic natural polymers were seen as promising devices for potential oral insulin delivery

Physicochemical and microstructural characterization of gum tragacanth added whey protein based films

Edible films of gum tragacanth (GT) with whey protein were fabricated to see how the incorporation of GT influenced whey protein based film properties. Whey protein isolate (WPI) was replaced with GT at different ratios as 0.5, 1, 1.5 and 2% of WPI. Optical, mechanical, permeability and microstructural properties, as well as moisture sorption and solubility behavior of films were measured. The findings indicated that combination of WPI and GT in film formulation led to less strength, more flexible, less soluble films with lower permeability to water and with higher opacity. The results suggested that the addition of GT to WPI could lead to obtain modified WPI based edible films with desirable properties

Development of photo-modulated non-toxic and adhesive smart gel films

Novel technologies combined with sustainable polymers have great importance for future developments. Polysaccharide gel and films present advantages of safety, renewability, and biodegradability. In this study, unmodified alginate was formulated with non-toxic components to be utilized in UV-induced printing and presented as an eco-friendly visual intelligent device. Riboflavin (RF) degradation upon UV and pH exposure was utilized to achieve photo-modulated specific patterns at 405 nm in SLA (Stereolithography) printer. They were successfully fabricated through an acid-induced ionic gelation process and printed via a UV-induced patterning process. 0.01% (w/v) riboflavin, 60:120 mM CaCO3: GDL concentration, printing time as 90 min, and sample volume as 15 ml/petri dish area led to a satisfied performance on UV-induced writing property giving contrast between written and blank regions as well as good texture. Due to the importance of pH and NH3 sensitivity of the gel films in food packaging, the colorimetric measurements proceeded. The results gave a tendency to more rapid color loss in alkaline conditions than in acidic environments indicating potential food storage applications. According to ammonia vapor sensitivity S (%), the films gave approximately half the value of S compared with the gels. Microstructural changes after the gelation process were also confirmed by FTIR. Photopatterning process on the pH responsive riboflavin enabled multipurpose photopatterning such as monitoring real-time freshness attaching to the inside or outside of the food storage material

Polysaccharide blended whey protein isolate-(WPI) hydrogels: A physicochemical and controlled release study

WOS: 000405058800005Design and characterization of composite whey protein isolate (WPI) hydrogels are gaining interest due to their utilization as controlled delivery matrices for bioactive agents. In this study, black carrot extract (BC) loaded composite WPI hydrogels, containing xanthan (XN), pectin (PC) and gum tragacanth (GT) were prepared by conventional water bath (CV) and infrared (IR) assisted microwave heating (MW). Release and swelling experiments were conducted at pH 7.0 phosphate buffer solution for 24 h. Highest swelling ratio (SR) was observed at CV XN hydrogels and only XN hydrogels showed a distinct increase in SR (17.85%) with respect to WPI hydrogels containing no additional polymer (10.55%) (p < 0.05). CV WPI hydrogels having no added polysaccharide showed the highest release percent (77.81%). CV PC, XN and GT hydrogels with release ratios of 37.15%, 32.79% and 29.39%, respectively, were capable of retarding release with respect to sole WPI hydrogels (p < 0.05). MW increased the release rates of all polymer added hydrogels. Nuclear Magnetic Resonance (NMR) relaxometry was used to understand the polymer water interactions in the samples. Therefore, transverse relaxation times (T-2) and self-diffusion coefficients (SDC) of each hydrogel were measured. Increasing T-2 and SDC values of CV XN samples were associated with better gel characteristics. Scanning electron microscope (SEM) images revealed the microstructural differences between the heating and polymer types. Mathematical modelling of release behaviors of hydrogels was also conducted to estimate diffusion coefficients. Moreover, this study introduces the effects of MW-IR heating on the physiochemical and controlled release behavior of WPI-GT composite hydrogels for the first time. (C) 2017 Elsevier Ltd. All rights reserved

Physical characterization of low-calorie chocolate formulations

Development of a high-quality low-calorie chocolate needs the use of the most appropriate ingredients that could substitute sugar without negatively affecting several product properties. In this study, sucrose-reduced chocolates sweetened with sucralose and stevia by using bulking agents were investigated in relation to their rheological, textural and sensory attributes. Dark, milk and white chocolates with different amounts of sweeteners were formulated. The Casson model best fitted to the rheological data. In dark chocolates, partial substitution of sucrose with stevia (DCSSt) gave similar plastic viscosity and yield stress values with control samples (DCS). Hardness measurements also supported these results. DCSSt sample was again found to be very similar to control in tested sensory attributes when assessed by a consumer panel. The data indicated that it was possible to manufacture chocolate by partial replacement of sucrose with stevia without adversely affecting its important rheological, textural properties and sensory acceptance

Recent advances in time domain NMR & MRI sensors and their food applications

Time domain nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are well-known non-destructive characterization techniques that are used to evaluate food quality. Time domain NMR is primarily based on relaxation and diffusion measurements from the signal coming from the whole sample whereas MRI enables visualization of the interiors of intact foods on a macroscopic scale without disturbing the sample based on the differences on relaxation and diffusion. A common perception that using NMR/MRI for testing food is costly is no longer valid with the advances in low-field bench top NMR/MRI instruments. This short review paper discusses the most recent developments and examples of time domain NMR and MRI based sensors for different food applications

Development of pH Sensitive Alginate/Gum Tragacanth Based Hydrogels for Oral Insulin Delivery

Insulin entrapped alginate-gum tragacanth (ALG-GT) hydrogels at different ALG replacement ratios (100, 75, 50, 25) were prepared through an ionotropic gelation method, followed by chitosan (CH) polyelectrolyte complexation. A mild gelation process without the use of harsh chemicals was proposed to improve insulin efficiency. Retention of almost the full amount of entrapped insulin in a simulated gastric environment and sustained insulin release in simulated intestinal buffer indicated the pH sensitivity of the gels. Insulin release from hydrogels with different formulations showed significant differences (p < 0.05). Time domain (TD) NMR relaxometry experiments also showed the differences for different formulations, and the presence of CH revealed that ALG-GT gel formulation could be used as an oral insulin carrier at optimum concentrations. The hydrogels formulated from biodegradable, biocompatible, and nontoxic natural polymers were seen as promising devices for potential oral insulin delivery