Spatiotemporal analysis of microstructure, sensory attributes, and full-spectrum metabolomes reveals the relationship between bitterness and nootkatone in Alpinia oxyphylla miquel fruit peel and seeds.

The Alpinia oxyphylla fruit (AOF) is a popular condiment and traditional Chinese medicine in Asia, known for its neuroprotective compound nootkatone. However, there has not been a comprehensive study of its flavor or the relationship between sensory and bioactive compounds. To address this issue, we examined AOF's microstructure, flavor, and metabolomic profiles during fruit maturation. The key markers used to distinguish samples included fruit expansion, testa pigmentation, aril liquefaction, oil cell expansion, peel spiciness, aril sweetness, and seed bitterness. A full-spectrum metabolomic analysis, combining a nontargeted metabolomics approach for volatile compounds and a widely targeted metabolomics approach for nonvolatile compounds, identified 1,448 metabolites, including 1,410 differentially accumulated metabolites (DAMs). Notably, 31 DAMs, including nootkatone, were associated with spicy peel, sweet aril, and bitter seeds. Correlational analysis indicated that bitterness intensity is an easy-to-use biomarker for nootkatone content in seeds. KEGG enrichment analysis linked peel spiciness to phenylpropanoid and capsaicin biosynthesis, seed bitterness to terpenoid (especially nootkatone) biosynthesis, and aril sweetness to starch and sucrose metabolism. This investigation advances the understanding of AOF's complex flavor chemistry and underlying bioactive principle, encapsulating the essence of the adage: "no bitterness, no intelligence" within the realm of phytochemistry.

Automatic microbial electro-Fenton system driven by transpiration for degradation of acid orange 7.

Microbial electro-Fenton system (MEFS) shows potential application for degradation of recalcitrant pollutants. In order to simplify the MEFS and adapt to the practical application situations, such as water, soil or sludge remediation, we developed an automatic MEFS (AMEFS) for degradation of a recalcitrant dye, acid orange 7. The AMEFS contained a microchannel-structured carbon decorated with iron oxides as electro-Fenton cathode. The AMEFS could be either two-electrode configuration that the microchannel-structured carbon connected with an additional bioanode by an external circuit, or single-electrode configuration that the microchannel-structured carbon served as both bioanode and cathode. Thanks to the microchannel structure of the carbon cathode, the AMEFS could be auto-driven by a process similar to the transpiration process of natural plants. The two-electrode AMEFS had higher degradation efficiency of acid orange 7 at lower external resistance, and achieved the highest degradation efficiency of 96% at the short-circuit condition. The single-electrode configuration simplified the setup of the AMEFS and possessed comparable performance with that of two-electrode configuration at short-circuit condition. Moreover, it could degrade high concentration acid orange 7 of up to 50 mg L-1 and achieve a high degradation efficiency of over 93%. The AMEFS could be applied for soil and sludge remediation by direct insertion of the microchannel structured carbon into contaminated body.