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6406908 
Journal Article 
Antimicrobial browning-inhibitory effect of flavor compounds in seaweeds 
Kajiwara, T; Matsui, K; Akakabe, Y; Murakawa, T; Arai, C 
2006 
Yes 
Journal of Applied Phycology
ISSN: 0921-8971
EISSN: 1573-5176 
18 
3-5 
413-422 
WOS:000242434900024 
Since ancient times, the antimicrobial properties of seaweeds have been recognized. However, antimicrobial activities of volatile compounds in seaweeds have not been explored so far. Here, essential oils from seaweeds including green, brown and red algae such as Laminaria japonica, Kjellmaniella crassifolia, Gracilaria verrucosa and Ulva pertusa were prepared by using SDE (simultaneous distillation and extraction) apparatus. Volatile compounds in the essential oils were identified as aldehydes, ketones, carboxylic acids, alcohols and hydrocarbons by comparison of GC-retention times and MS data with those of authentic specimens. Flavor compounds such as (3Z)-hexenal, (2E)-hexenal and (2E)-nonenal in some essential oils showed strong antimicrobial activities against Escherichia coli TG-1, and Erwinia carotovora. Inhibition of browning can be achieved during either of two stages, namely, oxidation reaction by tyrosinase or subsequent non-enzymatic polymerization. Tyrosinase activity was measured by monitoring absorbance at 475 nm originating from dopachrome formed from L-DOPA. Many kinds of aliphatic carboxylic acids, aldehydes and alcohols were used as inhibitors for PPO activity. The results indicated that the alpha , beta -unsaturated carbonyl compounds strongly inhibit tyrosinase activity. When seaweeds are damaged or macerated, the alpha , beta -unsaturated aldehydes such as (2E)-hexenal and (2E)-nonenal are biosynthesized via the corresponding (3Z)-unsaturated aldehydes from linolenic acid and arachidonic acid. The flavor compounds that are formed could be valuable as safe antimicrobial browning-inhibitory agents of edible seaweed origin. 
seaweeds; essential oils; volatile compounds; tyrosinase inhibitory activity; antimicrobial activity; L-DOPA