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 [ 15 N]ammonium ( 15 N ) 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- 13 C]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.

The aim of this study was to investigate the effects of addition of dietary fibers on rheological properties of batter and cake quality. Wheat flour was replaced by 5 and 10% (wt%) oat, pea, apple and lemon fibers. All cake batters showed shear thinning behavior. Incorporation of fibers increased consistency index (k), storage modulus (G') and loss modulus (G″). As quality parameters, specific volume, hardness, weight loss, color and microstructure of cakes were investigated. Cakes containing oat and pea fibers (5%) had similar specific volume and texture with control cakes which contained no fiber. As fiber concentration increased, specific volume decreased but hardness increased. No significant difference was found between weight loss of control cake and cakes with oat, pea and apple fibers. Lemon fiber enriched cakes had the lowest specific volume, weight loss and color difference. When microstructural images were examined, it was seen that control cake had more porous structure than fiber enriched cakes. In addition, lemon and apple fiber containing cakes had less porous crumb structure as compared to oat and pea containing ones. Oat and pea fiber (5%) enriched cakes had similar physical properties (volume, texture and color) with control cakes.

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