Foods

The edible and sensory quality of fermented fish products, particularly the formation of garlic clove-structured muscle flakes (GCMF), play critical roles in consumer acceptance and consumption. Herein, aiming to obtain the optimal technical process, this study systematically explored the generation and dynamic evolution of GCMF structure of fermented mandarin fish, especially the integrity and peeling properties of GCMF, which would profoundly determine the textural properties of fish flesh. Meanwhile, flavor profiles were also concentrated during the formation of GCMF. Specifically, our results showed that the optimal fermentation conditions were 3% salt concentration and 7 days of fermentation at 7 °C. Under these conditions, the physicochemical indicators (moisture, pH, TVB-N) of the fermented fish remained within reasonable ranges and the sensory score; peeling integrity of GCMF and the texture properties reached the highest values. In addition, with the increase in fermentation time, the content of undesirable flavor compounds, especially nonanal and 1-octen-3-ol, gradually decreased. Overall, these findings provide a theoretical framework for the evaluation of GCMF structure and for understanding flavor development in fermented mandarin fish, thereby laying a foundation for improved quality control of fermented fish products.

Air-dried pork coppa is highly favored for its unique organoleptic and flavor characteristics. However, the traditional long processing cycle and uncontrollable environmental conditions lead to unstable product quality. Staphylococcus mediates the reduction in nitrite to nitric oxide via nitrite reductase; the resulting nitric oxide then binds to myoglobin, forming nitrosylmyoglobin that endows meat products with a characteristic bright red. It could also improve the activity of lipase and protease, promoting the flavor. In this study, Staphylococcus carnosus and Staphylococcus xylosus as starter cultures have been applied to air-dried coppa. After Staphylococcus inoculation, the water activity and pH value of coppa significantly decreased compared with those of naturally fermented coppa (p < 0.05). Meanwhile, it improved the color and increased the hardness and chewiness, which in turn enhanced the overall taste of organoleptic acceptability. The ¹H NMR spectra showed that the main taste metabolites were free amino acids and organic acids. Citrulline, formic acid, isobutyric acid, and isovaleric acid might be the key metabolites distinguishing between those with or without Staphylococcus inoculation. This study suggested that inoculation with Staphylococcus xylosus and Staphylococcus carnosus played an important role in improving the physicochemical properties and taste development of coppa.

Grade and cultivar are the important factors influencing white tea quality, but their relative metabolic contributions are not fully understood. Twelve white tea samples representing four major Fujian cultivars across three grades were analyzed using UHPLC–MS-based non-volatile metabolomics, HS-SPME–GC–MS volatile profiling, and sensory correlation analysis. In total, 47 non-volatile and 21 volatile markers were associated with grade differences, while 44 non-volatile and 26 volatile markers were linked to cultivar differences. Catechins and amino acids declined as grade decreased, whereas flavonol glycosides and gallic acid increased, accompanied by stronger astringency and reduced umami and sweetness. Aroma profiles showed a similar trend, with higher-grade teas dominated by floral notes and lower-grade teas exhibiting more herbal characteristics. Dimeric catechins, oxylipins, and aroma glycosides varied among cultivars. Volatile profiles separated the cultivars into two aroma groups: Fuding Dabai and Fuding Dahao showed more floral–fruity aromas, whereas Fuan Dabai and Zhenghe Dabai exhibited stronger herbal and aged aromas. Odor activity value analysis showed that linalool, geraniol, and (E,Z)-3,6-nonadien-1-ol were among the most abundant aroma-active compounds across white tea samples. These results provide chemical evidence for distinguishing white tea by grade and cultivar, with potential relevance to quality evaluation.