Watermelon Dry Hopping

Pressed watermelon juice in secondary works great. It leaves a nice, slightly sweet, slighlty lip puckering flavor behind after secondary fermentation. Obviously won't be as sweet as the fresh juice. I use 8 cups of fresh pressed juice (using most of the fruit from the inside of one med-large watermelon, no rind, pressed through a fine straining basket) per five gallons of beer placing the juice in the bottom of the secondary and racking from primary on top of the juice. The leave it be for two weeks before bottling or kegging. I've done this with my american wheat ale recipe and it makes a fantastic summer brew!

 

What in the watermelon juice would leave sweetness after fermentation? AFAIK, the only sugars in watermelon are fructose, glucose, and sucrose. If so, these should all ferment out completely.

 

@VikeMan - I'm not a watermelon expert but I'd assume there's more chemicals in watermelon that give it its sweet flavor other than the sugars. If not, watermelon extract would have little to no sweetness, right? The base beer was an American wheat ale, maybe there was some residual sweetness in the beer after primary fermentation? It's not sweet like the juice itself but there's definitely a touch of that still there.

@Dmanuele - I didn't bother trying to sanitize the juice itself. However, I did sanitize everything that would be used in producing the juice (knife,cutting board, strainer, spoon or other tool to help push watermelon through the strainer, and a bowl) to be on the safe side. I think the juice doesn't have a significant need for sanitation as adding it to secondary exposes it to the alcohol in the beer which has some sanitizing properties. Also, you are not using the exterior of the melon which is the part that would be exposed to environmental contamination. I figure the inside of the melon should have little to no bacterial or yeast content unless it is rotting or punctured prior to your first cut with a sanitized knife. If it makes you feel better, you could sanitize the outside of the melon too.

 

I think watermelon extract tastes sweet because it's made with propylene glycol, which tastes sweet. It seems to me that if there were a naturally occurring substance in watermelon (other than sugar) that tastes sweet, the non-sugar sweetener industry would be all over it.