This study investigates the potential use of biochar derived from residues-such as spruce wood, spent coffee grounds, tea waste, and nutshells-as a sustainable coal substitute-to enhance the decarbonization of European energetic systems and decrease the dependence on fossil fuels. The biomasses were pyrolyzed at 250-550 °C, analyzed for calorific value and composition, and evaluated for energy retention and mass loss. The results show significant energy density improvements, with optimal temperatures varying by material (e.g., spruce wood reached 31.56 MJ·kg-1 at 550 °C, retaining 21.84% of its mass; spent coffee grounds peaked at 31.26 MJ·kg-1 at 350 °C, retaining 37.53%). Economic analysis confirmed pyrolyzed biomass as a cost-effective alternative to coal, especially considering emission allowance costs. Integrating biomass pyrolysis into regional energy systems supports decarbonization, reduces emissions, and advances us towards a circular economy.

• Klíčová slova
• biochar, biomass, calorific value, energy residual, nut shells, spent coffee ground, spruce wood, tea waste,
• Publikační typ
• časopisecké články MeSH

BACKGROUND/OBJECTIVES: This study tested the influence of in vitro digestion on the release of organic acids and low molecular weight saccharides of matcha. METHODS: The concentrations of analytes in the raw and undigested portion of matcha were measured using HPLC with spectrometric and refractometric detection to establish their residual values after a two-step enzymatic digestion that was finally presented as a retention factor. RESULTS: It was established that dry matter digestibility values after simulated gastric and both gastric and intestinal phases were 67.3 and 85.9%, respectively. Native matcha, citric acid (44.8 mg/g), malic acid (32.2 mg/g), trehalose (36.1 mg/g), and L-arabinose (8.20 mg/g) reached the highest values and were predominant, whereas D-fructose, xylose, maltose, and saccharose were not detected. Regarding gastric phase digestion, succinic and malic acids, trehalose and D-glucose were the worst-releasing compounds and their remaining factors reached 34, 19, 18, and 50%, respectively, whereas L-arabinose was completely released. Focusing on gastric and small intestinal digestion, the least-releasing compounds of matcha tea leaves were succinic acid and trehalose, with their retention factors at 7 and 13%, which can proceed with the leaf matrix to the large intestine. CONCLUSIONS: Malic, oxalic, and citric acids, the carbohydrates D-glucose, L-arabinose, and L-rhamnose, are almost entirely released from matcha tea during digestion in the stomach and small intestine and can be available for absorption in the small intestine. In the measurement of oxalic acid, considering that the process of shading tea leaves increases the concentration of this acid and its retention factor value is too small, it would be appropriate in the future to evaluate the recommended maximum daily intake of matcha tea for people sensitive to the formation of urinal stones.

• Klíčová slova
• Camellia sinensis, bioactive compound, foods, green tea, in vitro digestion, low molecular weight carbohydrate, matcha, organic acid,
• MeSH
• čaj * chemie   MeSH
• kyselina citronová MeSH
• listy rostlin chemie   MeSH
• maláty MeSH
• molekulová hmotnost * MeSH
• sacharidy chemie   MeSH
• trávení * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• čaj * MeSH
• kyselina citronová MeSH
• maláty MeSH
• malic acid MeSH Prohlížeč
• sacharidy MeSH