I cooked some brown rice, but it didn't get cooked all the way through.
I made some brown rice but it was undercooked because I didn't soak it long enough.
この場合、次のような言い方ができますよ。
ーI cooked some brown rice, but it didn't get cooked all the way through.
「玄米を炊いたら、芯が残っていた」
didn't get cooked all the way through で「芯が残っていた」と言えます。
ーI made some brown rice but it was undercooked because I didn't soak it long enough.
「玄米を炊いたら、水に浸ける時間が十分でなかったため芯が残っていた」
it was undercooked でも「芯が残っていた」と言えます。
to soak で「浸ける」
ご参考まで！
カナダ 
