No abstract

In this study, Alliinase extracted and purified from shallots was comprehensively examined. Its molecular weight was determined as 50 kDa, and its optimal working conditions were identified as pH 8 and 40 º C. Its activity was significantly and positively affected by the metals K + , Na + , Ga 2+ , Mg 2+ and Fe 2+ . Purified Alliinase was immobilized by alginate and the optimized conditions for this process were: a sodium alginate concentration of 2.5%, a CaCl 2 concentration of 4.0%, a Glutaraldehyde concentration of 0.75%, and a ratio of sodium alginate solution and Alliinase solution (by volumn) of 4:3. The ability for free Alliinase and immobilized Alliinase to release flavours from shallots was compared. It was found that immobilization did not compromise Alliinase's flavor releasing ability. They both released 36 flavouring chemicals from the flavouring precursor, with a similar ratio. This study provided fundamental information for further commercial development of Alliinase produced from shallots.

The aim of this study was to extract the polyphenols from three major seaweed species such as Sargassum miyabei, Undaria pinnatifida suringar, and Sargassum thunbergii, which are found in the coastal province (Guangdong), a longest coastal line in China. It was found that the Sargassum thunbergii produced more polyphenols (34.99 mg) as compared to Sargassum miyabei (23.26 mg) and Undaria pinnatifida suringar (25.34 mg), respectively. The orthogonal method was used for the extraction of phenolic compounds and extraction condition of each seaweed species was optimized. The antioxidant activity of extracted polyphenols from all three species stated that the polyphenols extracted from Undaria pinnatifida suringar demonstrated the highest antioxidative activity. Furthermore, gas chromatography–mass spectrometry (GC‐MS) was used for qualitative analysis of polyphenols, which revealed that the major components of polyphenols extracted from Undaria pinnatifida suringar were gallic acid and arbutin followed by syringate in Sargassum miyabei and phloretin in Sargassum thunbergii.