A class of flavonoid aminated derivatives that had been consistently overlooked in literature was shown to be formed as artefacts in cell culture medium. In this study, 34 flavonoids from different subclasses were incubated in Dulbecco's modified Eagle's Medium (DMEM) at 37°C for 2 h to identify the reaction mechanism behind aminated derivatives formation from flavonoids. Baicalein, scutellarein, dihydromyricetin, (−)‐gallocatechin (GC), (−)‐epigallocatechin (EGC), (−)‐GC gallate, and (−)‐EGC gallate were found to yield corresponding nitrogenous derivatives in both DMEM and amino acid solution. The nitrogen source of these seven flavonoid ‐aminated derivatives was revealed to be amino acids in DMEM. The pyrogallol group of the flavonoids was a key structural motif, being first oxidized into quinone and then further reacting with amino acids (Strecker degradation) to yield aminated flavonoids and corresponding aldehydes. A slightly alkaline environment accelerated the amination of flavonoids, possibly via the formation of flavonoid quinone. These results provide the mechanistic evidence for the in vitro generation of flavonoid ‐aminated derivatives, yet to be tested using in vivo assays.

The choice of tea utensils used for brewing significantly impacts the sensory and chemical attributes of tea. In order to assess the influence of various tea sets on the flavor and chemical composition of different tea varieties, a combination of sensory evaluation and high-performance liquid chromatography was employed. The results showed that the content of amino acids in the tea liquid brewed with tin tea utensils was relatively higher, which could exhibit freshness in taste, thus suitable for brewing green tea and white tea. The content of polyphenols, soluble carbohydrates, and water extract in the tea liquid brewed with a porcelain tea set was relatively higher; the sweetness and thickness of the tea liquid were increased, so it was more beneficial to brew black tea. The purple sand tea set was suitable for brewing oolong tea and dark tea, and could endow their respective quality characteristics. Ultimately, these research findings provide a scientific basis for the selection of tea utensils tailored to different types of tea.

Chrysanthemum morifolium Ramat., known as Hangbaiju (HBJ), is a high-value edible, medicinal product where the flowers are infused in hot water and drunk as tea. Its quality and efficacy are closely related to its geographical origin. Consequently, it is vulnerable to fraudulent substitution by other lower-value Chrysanthemum products. In this study, cultivation (variety and different growth stages) and isotopic fractionation between the flower, stem, and leaf were studied. Samples from four different HBJ varieties were characterized using stable isotopes (δ¹³C, δ¹⁵N, δ²H, δ¹⁸O, %C, and %N) across three producing regions in Zhejiang province, China. The results showed that there were no significant differences in stable isotopic compositions for different HBJ varieties, but there were significant differences for different plant tissues (flower, stem, leaf, etc.). Furthermore, the stable isotopic composition altered dramatically at different growth stages. The δ¹⁵N (r = 0.6809) and δ²H (r = 0.6102) correlations between stems and leaves (SL) and flowers (F) of HBJ were relatively good, the δ¹³C correlation (r = 0.2636) between SL and F was weak, but δ¹⁸O correlation (r = 0.01) had almost no correlation. A supervised multivariate statistical model (partial least squares discriminant analysis, PLS-DA) was used to discriminate three different producing regions with high accuracy (66.7%, 66.7%, and 100%, respectively). Our findings show that stable isotopes combined with multivariate statistical analysis provide an effective method for the geographical identification of HBJ.

Polyphenols tend to be oxidized to form o‐quinones (1,2‐carbonyl), significantly catalyzed by elevated temperatures, like the ones occurring during thermal processing. During food processing, both Strecker degradation—primarily involving α‐dicarbonyl compounds reacting with amino acids—and polyphenol oxidation—where o‐quinones can react with amino acids—spontaneously occur. These distinct pathways each contribute to the formation of characteristic aroma compounds and browning pigments, thereby influencing the final quality and sensory properties of the food. The aminated derivatives of polyphenols from Strecker degradation have long been ignored by the researchers. This review highlights the occurrence, mechanism, significance, and benefits of the aminated polyphenols formed during food processing to provide a perspective on the development of new functional components. Temperature significantly affects Strecker degradation. In the presence of complex polyphenols with a pyrogallol group, Strecker degradation can happen at room temperature (25°C) or body temperature (37°C). For example, tea catechins readily take place Strecker degradation with amino acids at 37°C to yield aminated polyphenols. Although the aminated polyphenols have not been reported in food raw materials, the aminated polyphenols metabolites (4′‐NH₂‐EGCG, 4′‐NH₂‐myricetin, 3′‐methyl‐4′‐NH₂‐myricetin, 5‐NH₂‐baicalein and 6‐NH₂‐baicalein) have been discovered in vivo. There is no data on the functions of NH₂‐flavonoids in vivo. NH₂‐flavonoids are much more stable than their precursor flavonoids, potentially providing longer interaction time with the body.

Stable isotope analysis is a powerful and increasingly applied tool for food traceability, enabling high‐confidence determination of origin, production practices, and authenticity. This guideline provides practical recommendations for the preparation and analysis of solid and liquid food samples using stable isotope techniques. Carbon, nitrogen, and sulfur isotopes are typically measured using elemental analysis coupled with isotope ratio mass spectrometry (EA‐IRMS), whereas hydrogen and oxygen isotopes due to their volatility and exchangeability are best analyzed using high‐temperature conversion elemental analysis (HTEA‐IRMS). Emphasis is placed on harmonized protocols for sample preparation, including drying, encapsulation, and homogenization, and on the use of internationally recognized isotope reference scales: Vienna Pee Dee belemnite (VPDB) for carbon, atmospheric air (AIR) for nitrogen, Vienna standard mean ocean water (VSMOW) for hydrogen and oxygen, and Vienna Canyon Diablo troilite (V‐CDT) for sulfur. Best practices for selecting and applying certified reference materials, multipoint normalization, correcting for instrument linearity, and uncertainty propagation using regression approaches are discussed. Quality control measures—such as blanks, replicates, and matrix‐matched standards—are essential to ensure reproducibility and interlaboratory comparability. These guidelines aim to standardize stable isotope methodology in food science and support users in producing accurate, defensible, and globally comparable isotopic data.

The effect of fertilizer supply and light intensity on the distribution of elemental contents (%C and %N) and light stable isotopes (C, N, H, and O) in different rice fractions (rice husk, brown rice, and polished rice) of two hybrid rice cultivars (maintainer lines You-1B and Zhong-9B) were investigated. Significant variations were observed for δ¹³C (−31.3 to −28.3‰), δ¹⁵N (2.4 to 2.7‰), δ²H (−125.7 to −84.7‰), and δ¹⁸O (15.1‰ to 23.7‰) values in different rice fractions among different cultivars. Fertilizer treatments showed a strong association with %N, δ¹⁵N, δ²H, and δ¹⁸O values while it did not impart any significant variation for the %C and δ¹³C values. Light intensity levels also showed a significant influence on the isotopic values of different rice fractions. The δ¹³C values showed a positive correlation with irradiance. The δ²H and δ¹⁵N values decreased with an increase in the irradiance. The light intensity levels did not show any significant change for δ¹⁸O values in rice fractions. Multivariate ANOVA showed a significant interaction effect of different factors (light intensity, fertilizer concentration, and rice variety) on the isotopic composition of rice fractions. It is concluded that all environmental and cultivation factors mentioned above significantly influenced the isotopic values and should be considered when addressing the authenticity and origin of rice. Furthermore, care should be taken when selecting rice fractions for traceability and authenticity studies since isotopic signatures vary considerably among different rice fractions.