I emailed Henry about the difference in colour and this is his answer. ( which, BTW, seems legit )
Actually, its color is not very important. Some customers told us that pale yellow RU was better, but others told us that white/off-white RU was better. In fact, even the 0.001% content of segment (which is not harmful) could change its color, but its active content is also above 99.2%. During manufacture, there one step process, which is decolorization by active charcoal. After declorization, its color should be white or off-white. But sometimes, remained trace segment could make its color pale yellow.So please don't worry about its color. If you have other questions, please reply us and have a talk.