and the area under the curve of the broad band increased. Since the degumming ratio did not changed significantly after 60 min of extraction, these results indicate that there is some degradation of the AmS by Na2CO3 when the extraction time is extended. The maximum peak of the broad band was down-shifted, also indicating the degradation of the AmS. The effect of the sodium carbonate concentration is illustrated in Fig. 4. The degumming ratio reached a plateau (15.5±1.0%) at the 0.02 M concentration (Fig. 4A); a further increase of the sodium carbonate concentration did not change the degumming ratio significantly. However, the MWD of the extracted AmS was affected by the concentration of sodium carbonate. Similar to the effect of the extraction time, the increased sodium carbonate concentration led to the degradation of the AmS (Fig. 4B). From the materials aspect, a higher molecular weight leads to improved mechanical properties. In the case of synthetic polymers, the degree of polymerization should be sufficiently high, whereas for natural polymers, the extraction conditions should be mild enough in order not to degrade the natural molecular weight. Therefore, it might be preferable to extract a higher-MW AmS even though the extraction yield is low. However, this is not a rule of thumb in the case of proteins. Whereas most synthetic polymers are constructed as a linear chain, proteins have their own three-dimensional structures that are not conductive to the chain entanglement as are synthetic polymers. Therefore, it is not always recommendable to use a high-MW polymer for enhancing the mechanical properties. The mechanical properties of any form of the extracted AmS are beyond the scope of this study; however, there are other references that provide this speculation [18,24]. However, if the aim is to extract a relatively high-MW AmS, then it is recommended that a shorter extraction time and/or low sodium carbonate concentration be employed.