Yes there is - purl through the back loop if you're doing stockinette (you have to insert your needle from behind the stitches on your needle to do this). But, it's hard to say if you have to do this on the WS without knowing what type of stitch pattern you're doing. Some involve just purling the twisted stitches on the WS and others twist the WS purled stitches too. If you were knitting in the round and twisting on only every other row, just purl regularly on the WS.