OpenJDK does not have a native JPEG encoder, try using Sun’s JDK, or using a library (such as JAI
AFAIK, regarding the “pinkish tint”, Java saves the JPEG as ARGB (still with transparency information). Most viewers, when opening, assume the four channels must correspond to a CMYK (not ARGB) and thus the red tint.
If you import the image back to Java, the transparency is still there, though.