To investigate the effects of different processing methods on the characteristic flavor of Undaria pinnatifida, this study systematically compared the volatile flavor compositions of four sample groups, namely fresh U. pinnatifida from Dalian (WD), salted U. pinnatifida from Dalian (WY), dried U. pinnatifida from Dalian (WG), and fresh U. pinnatifida from Shantou (WS), using GC-IMS, combined with relative odor activity value (ROAV) analysis. The results showed that GC-IMS effectively distinguished the volatile profiles of samples subjected to different processing methods, identifying a total of 45 flavor compounds. Aldehydes emerged as the key flavor components, accounting for relative contents of 53.85% (WD), 41.12% (WY), 52.62% (WG), and 45.28% (WS), which were significantly higher than those of other compound classes. The ROAV analysis revealed that 1-octen-3-ol and 1-octen-3-one were the characteristic compounds shared by all four sample groups. Furthermore, distinct processing methods influenced the distribution of saturated aldehydes, esters, and furans, which could serve as key indicators to distinguish between different processing techniques. Multidimensional analysis, including GC-IMS fingerprint visualization and principal component cluster analysis, confirmed significant flavor differences among the samples from different processing methods and origins. This study provides a theoretical basis for the quality control and standardized production of algal-based foods by multidimensionally analyzing flavor evolution in U. pinnatifida during processing.

The fishy odor of salted kelp, mainly derived from halogenated hydrocarbons, sulfur-containing compounds, and free fatty acids, limits its sensory quality and market value. This study evaluated microbial deodorization using six food-grade strains—Pichia kluyveri, Saccharomyces cerevisiae, Wickerhamomyces anomalus, Lactiplantibacillus plantarum, Limosilactobacillus fermentum and Pediococcus pentosaceus—in single and co-fermentation systems. GC-IMS, relative odor activity values, and sensory evaluation identified 1-octen-3-one as the dominant off-odor compound. Fermentation significantly reduced 1-octen-3-one while increasing aroma-active volatiles such as isovaleraldehyde, isopentanol, and isopropyl propionate, likely through enzymatic degradation and microbial biosynthesis. Sensory analysis confirmed improvements in aroma and overall acceptability with minimal changes in color and texture. These findings clarify microbial modulation mechanisms of kelp flavor and support the development of value-added fermented kelp products.

As dietary preferences diversify, aquatic foods remain a global staple, providing high-quality protein, essential fatty acids, and other essential nutrients. However, maintaining the quality and safety of seafood remains challenging. Salting is the primary postharvest processing method for the brown seaweed Undaria pinnatifida and can affect product quality and lead (Pb) accumulation. This study investigated changes in nutritional components, bioactive compounds, and Pb content throughout the harvest season and subsequent blanching and salting. Relationships among these variables were examined to identify suitable salting conditions. Samples were collected at nine 7-day intervals from the coastal waters of Dalian, China, and analyzed at the fresh, blanched, and salted stages. The maximum protein and alginate contents in fresh samples were 21.95% and 36.60% (dry weight), respectively, with a corresponding Pb content of 0.235 mg/kg. Principal component and Pearson correlation analyses showed that Pb accumulation was associated with protein and alginate contents. Salting with 40% salt for 48 h preserved favorable texture and color while maintaining Pb content below 0.35 mg/kg. These findings indicate that both harvest stage and processing affect nutritional quality and Pb levels. Although salting promotes Pb accumulation, controlling salt concentration and salting duration can limit this effect while preserving product quality. Salting with 40% salt for 48 h is therefore suggested as a suitable condition for producing salted U. pinnatifida with desirable texture, color, and Pb content. These findings provide a scientific basis for improving the quality and safety of salted brown algal products.