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[Display omitted] • Heating under 100–110 ℃ offered best taste characteristics and color appearances. • Isomerization, degradation and Maillard reactions are mainly involved. • 110 ℃ was the critical temperature point for enhancing antioxidant capacities. As the final processing step, drying temperature between 90 and 140 ℃ is usually applied to terminate enzymatic activities and improve sensory characteristics of black tea. Liquid chromatography tandem mass spectrometry (LC-MS) based non-targeted and targeted metabolomics analyses combined in vitro biological assays were adopted to investigate the chemical and biological variations after drying. Fifty-nine differentially expressed metabolites including several hydroxycinnamic acid derivatives and pyroglutamic acid–glucose Amadori rearrangement products (ARPs) were identified, the latter of which was correspondingly accumulated with increasing temperature. The levels of theaflavins (TFs), thearubigins (TRs), monosaccharides and free amino acids gradually decreased with increasing temperature. Furthermore, the bioassays of black tea showed that drying under 110 ℃ provided the highest antioxidant capacities, but the inhibitory effects on α -glucosidase and α -amylase were decreasing along with increasing drying temperature. These results are valuable for optimizing drying process to obtain superior sensory properties and preserve bioactivities of black tea. [ABSTRACT FROM AUTHOR]

[Display omitted] • Drying temperature (DT) markedly affected black tea non-volatile metabolites (NVMs) • Umami taste, sweet taste, and bright color were the highest under a DT of 90 °C. • WGCNA and MFA identified 455 NVMs related to objective indicators of black tea. • Among black tea samples with different DTs, 169 differential NVMs were identified. • Flavonoids, amino acids, phenolic acids, and lipids were the key differential NVMs. Drying temperature (DT) considerably affects the flavor of black tea (BT); however, its influence on non-volatile metabolites (NVMs) and their correlations remain unclear. In this study, an objective quantification technique and widely targeted metabolomics were applied to explore the effects of DT (130 °C, 110 °C, 90 °C, and 70 °C) on BT flavor and NVMs conversion. BT with a DT of 90 °C presented the highest umami, sweetness, overall taste, and brightness color values. Using the weighted gene co-expression network and multiple factor analysis, 455 sensory trait-related NVMs were explored across six key modules. Moreover, 169 differential NVMs were screened, and flavonoids, phenolic acids, amino acids, organic acids, and lipids were identified as key differential NVMs affecting the taste and color attributes of BT in response to DT. These findings enrich the BT processing theory and offer technical support for the precise and targeted processing of high-quality BT. [ABSTRACT FROM AUTHOR]

• More aldehydes and FAAs were observed at 40℃ and contributed to excellent flavor. • Some fatty acids were identified as potential flavor precursors. • Thirteen key volatile compounds were contributed to the overall aroma. • Six volatile compounds were screened as flavor markers to distinguish varied groups. • Lipid oxidation and protein degradation are the main sources of flavor at 40 ℃. Drying is an important process that can impart a different flavor to dried fish. The differences and sources of flavor of semi-dried golden pompano at different drying temperatures (40, 48, and 56 °C) were investigated, and the sensory quality, flavor substances, nonenzymatic reactions, and protein degradation were analyzed. Significant flavor differences were observed among different drying temperatures (P < 0.05), with several sensory properties showing superior results in the 40 °C group. Thirteen volatile compounds that contributed to the overall aroma were screened according to the relative odor activity value. Glu (umami taste) and Ala (sweet taste) were identified as key flavor substances based on the taste activity value. Nonanal, hexanal, heptanal, acetoin, pentadecane, and octanal represented the flavor markers. The flavor sources at higher drying temperatures included the joint action of lipid oxidation and the Maillard reaction, while those at lower temperature were lipid oxidation and protein degradation, which increased the aldehyde and free amino acid levels in the product, thus leading to the best flavor. [ABSTRACT FROM AUTHOR]

• GA cross-linking improved the application properties of collagen casing films. • Superior mechanical properties could be obtained by regulating drying temperature. • GA cross-linking improved the low temperature thermostability of films. • GA cross-linking impeded the depolymerization of collagen triple helix. • Higher drying temperatures disrupted the orientation of collagen fibers. The physicochemical properties of collagen casings were successfully improved by glutaraldehyde (GA) cross-linking, where the properties could be further regulated by drying temperature. Transverse direction (TD) showed a lower heat shrinkage rate than that in machine direction (MD). GA cross-linking significantly improved the mechanical properties of films under wet and boiled state. The mechanical properties of films in MD were more susceptible to wet and boiling water. The chemical composition was unchanged after GA cross-linking, but higher drying temperatures led to higher triple helix contents. The GA cross-linking mainly promoted the low temperature thermostability of collagen casings. All film samples had a rough fibrous morphology and a majority of collagen fibers was oriented under the lower drying temperature (55 ℃). These results reported in this study can be used to better guide the preparation of collagen casings. [ABSTRACT FROM AUTHOR]