Actually, you have two different situations. The first one, from the novel, the term berkunyit means, rubbing the skin with turmeric scrub. This is a traditional practice that somehow could help reduce the body heat. That's why the Dutchman was asking, aren't you feeling hot? Did you have you skin rub with turmeric?

On the other hand, the phrase panas berkunyit is not a common phrase. In fact, it sounded mismatched, as if the writer just picked the phrase for lack of other alternative. However, panas does mean HOT. And kunyit, a kind of spice, does make your cooking more delicious, if you cook it right. So, what crosses my mind when reading 'panas berkunyit' from google search is just that, hot and delicious news/gossip.

Hope that this could be of any help.

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Note added at 3 days3 hrs (2012-01-22 18:23:40 GMT)
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Just found out that berkunyit means DIRTY as in dirty minded; used by some group of youngsters

Turmeric - yellow - yellow culture