1H NMR spectroscopy applied to identify chemical aging markers in green coffee (Coffea arabica L.).

Nuclear magnetic resonance (NMR) was used to identify metabolic changes in green coffee beans stored in 3 different packages. Sensory and NMR analyses were performed at 0, 3, 6, 9, 12 and 18 months of storage. The decrease in the sensory quality of beverages by aging was more pronounced in the paper bags after 6 months of storage. High barrier bags and vacuum packs were able to maintain quality for 18 months of storage, regardless of the coffee processing method. The NMR technique allowed the differentiation of coffee packed in paper bags from the 3rd month of storage. These results indicate that it is possible to anticipate by up to 3 months the identification of changes that would otherwise only be noticed through sensory analysis after six months of storage. Choline and glycerophosphocholine are the main chemical compounds associated with the changes observed in the storage of green coffee in paper bags.

Mechanistic investigation of enolate/stabilized vinylogous carbanion-mediated organocatalytic azide (3 + 2) cycloaddition reactions for the synthesis of 1,2,3-triazoles.

Herein, we report a fully detailed mechanistic study involving an organocatalyzed 1,3-dipolar cycloaddition via enolate or stabilized vinylogous carbanion intermediates and azide for the synthesis of 1,2,3-triazoles. A detailed investigation of the elementary steps, intermediates, and transition states of the two organocatalyzed metal-free click reactions is supported by DFT calculations and 1H NMR monitoring experiments, providing detailed profiles for both reaction mechanisms. Distortion-interaction activation-strain (DIAS) analysis was also employed to further elucidate the regioselectivity in both reactions.

Metabolite Profiling by UPLC-MSE, NMR, and Antioxidant Properties of Amazonian Fruits: Mamey Apple (Mammea Americana), Camapu (Physalis Angulata), and Uxi (Endopleura Uchi).

The metabolite profiling associated with the antioxidant potential of Amazonian fruits represents an important step to the bioactive compound's characterization due to the large biodiversity in this region. The comprehensive bioactive compounds profile and antioxidant capacities of mamey apple (Mammea americana), camapu (Physalis angulata), and uxi (Endopleura uchi) was determined for the first time. Bioactive compounds were characterized by ultra-performance liquid chromatography coupled to high resolution mass spectrometry (UPLC-MSE) in aqueous and ethanolic extracts. Globally, a total of 293 metabolites were tentatively identified in mamey apple, campau, and uxi extracts. The main classes of compounds in the three species were terpenoids (61), phenolic acids (58), and flavonoids (53). Ethanolic extracts of fruits showed higher antioxidant activity and total ion abundance of bioactive compounds than aqueous. Uxi had the highest values of phenolic content (701.84 mg GAE/100 g), ABTS (1602.7 µmol Trolox g-1), and ORAC (15.04 µmol Trolox g-1). Mamey apple had the highest results for DPPH (1168.42 µmol TE g-1) and FRAP (1381.13 µmol FSE g-1). Nuclear magnetic resonance (NMR) spectroscopy results showed that sugars and lipids were the substances with the highest amounts in mamey apple and camapu. Data referring to chemical characteristics and antioxidant capacity of these fruits can contribute to their economic exploitation.