Cross pollination issue?

[BierGut]

I grew 5 different varieties this past summer. All did very well and smelled green and resinous when they were young. When it came time to harvest however they all had an onion like smell. Afraid to use them and ruin a good beer, I vacuum packed them and threw them in the freezer. Talking with a fellow brewer he asked if I had any onions growing nearby and I do have a lot of wild onion growing in the backyard. So I'm wondering if I have a cross pollination issue here? Has anyone had similar experiences?

 

[GVH_Dan]

Shoot, MJ is a cousin to hops and I know a lot of stoners that have been trying forever to cross breed them without success. I doubt an onion could.

Depending on what you are growing, it could be natural or a sign of oxidation.

Some varieties, like centennial, have an onion odor present. Its really pronounced when we turn them into pellets. But in most cases it doesn't come out in the beer.

Sometimes, its an indication that they weren't dried fast enough or far enough and started to oxidize.

If I were you, take some out of the freezer, boil up a hop tea and see if you smell any onion or other disturbing smells/flavors.

 

[Jaltwies]

Depending on the variety the onion aroma may be normal (CTZ for example). However it sounds like they may be over ripe. Crush some in your hands and take a sniff. Then let them sit for 15 minutes or so. If the aroma dissipates then it is likely varietal. If it persists then you've got oxidation by products. Those will likely go away if you plan to use them as bittering but not for dry hopping.

Timing harvest is difficult.