Studies on the stability of secoisolariciresinol diglucoside in flaxseed powder
Secoisolariciresinol diglucoside (SDG) (Fig.1) is an essential component (11.9 to 25.9g/kg ) of lignans in flaxseeds. Recently, SDG has drawn more and more attention because of its health benefits. A number of animal studies have shown that SDG may help fight many diseases in the modern society, including breast cancer , cardiovascular malfunction , diabetes  and prostatic hyperplasia . With a novel perspective, we focused our study on the effect of food processing methods, including steamed, boiled, fried and deep fried, and processing times on the stability of SDG in flaxseed powder.
In this paper, the samples of four processing times were prepared for each processing method. The concentrations of SDG in different samples were determined by RP-HPLC . The chromatographic analysis was performed on a Diamonsil C18 column (150*4.6mm, 5µm). Acetonitrile and 1% aqueous acetic acid was selected as the mobile phase. The detection wavelength was 280nm.
A comprehensive study on the effects of different processing methods was made in Fig.2. For steaming process, little effect on SDG content was observed. While for the boiled dishes, i.e. the medicated soups, although little impact was exerted on the content of SDG in flaxseed powder remnant, small amount of SDG was released from flaxseed into the filtrate (the soup). As for fried and deep fried dishes, the loss of SDG was inevitable, but shorter processing time lead to less decrease in SDG, flaxseed could also be employed if cooked properly.
Acknowledgement: This research work was supported by the Research Council of Zhejiang University and Skyherb Ingredients.
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