Comparison of New Zealand and commercial wakame (Undaria pinnatifida) in terms of physicochemical characteristics, sensory properties and volatile composition
Balbas, Jessica Marie Garcia
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The brown algae, Undaria pinnatifida, known as wakame is native to Japan, Korea, and China, was accidentally introduced to the New Zealand waters in 1987 and the species was categorised as an unwanted organism under the provisions of the Biosecurity Act 1993. Attempts were made to eradicate and/or control its growth in New Zealand with little success. Meanwhile, it has been recognized as having economic importance in wakame producing countries owing to the amount produced, consumed, and exported. The main aim of the project was to compare New Zealand wakame produced from U. pinnatifida in terms of physicochemical, sensory and volatiles analysis with commercial Japanese and Korean samples. This research investigated the free carbohydrates in processed Undaria (wakame). Furthermore, an investigation was made into the sensory properties of New Zealand wakame, its texture and colour profiles were compared to commercially available varieties from Japan and Korea. A volatile profile analysis was also carried out to help identify key flavour and odour compounds present in the seaweed. Results showed that the only free carbohydrate in Undaria is mannitol, the main photosynthetic by-product in phaeophytes. Mannitol concentration is also higher in freeze-dried samples compared with commercially prepared ones that have undergone blanching, salting, and oven-drying. New Zealand wakame processed in August was perceived to be different from commercially available wakame and was described as being fishy, thin, soft, and watery. Further analysis on the texture profile of the different samples confirmed this finding and an improvement in the processing method showed an increase in hardness for the processed New Zealand samples in October. The volatile profile analysis also identified 105 compounds present in the different wakame products which provided an insight as to what volatiles characterise one sample from the rest.