Don't know about ice cream specifically, but for rum cream, they use rum essence rather than rum liquor. You'd need so much liquor to get the flavor people expe

Don't know about ice cream specifically, but for rum cream, they use rum essence rather than rum liquor. You'd need so much liquor to get the flavor people expect, it wouldn't be creamy anymore. I expect the same is true of other rum-flavoured things. Rum essence can be alcohol-based, but propylene glycol also is common and works just fine.