Can dry hopping kill/prevent lacto infections?

[bionara]

I found it quite hard to find some info on this on google/forums so thought I'd ask!

I recently made a 1G wheat beer which I split in 2 and added raspberries to one, strawberries to the other. After a week or so they developed a sour smell and taste, with small ice-like chunks on the surface. Verdict: lacto infection!

I'm quite adventurous, so riding it out. Sadly the bastard seemed to spread to its neighbour which was an old peculiar clone, which I bottled to try and save.

Anyway, I'm paranoid about my future brew getting infected. It's been in primary for 8 days, and there are tiny white floaties: probably harmless. But! Does dry hopping kill or at least inhibit lacto growth?

The bucket was washed throughly, dishwashed, and sanitised between uses.

 

[CadillacAndy]

I would start by looking at equipment that touched each of these infected batches. If you used a siphon, funnel, tubing, etc I'd probably recommend replacing any cheaper plastic parts, or at least bleach bombing everything.

As far as dry hopping goes, I would guess it would have some effect, but if the bacteria has already taken hold to the point where you're seeing signs of a pellicle forming, I would highly doubt it would be enough.

Hops act as an anti-microbial by coating the cells with resin and keeping them from reproducing. If there is already a colony formed, you're too late. Also, different strains of lacto are effected differently by hops. Some are much weaker than others.

 

[Paradigm]

Hops do have a natural, slightly preservative effect, but like cadillacandy said, if it's infected I don't think you could fix it with hops. He seems to know a lot more than I, though

 

[Captain Damage]

Elephant in the room: unpasreurized fruit is loaded with lactobacillis!

 

[CadillacAndy]

Elephant in the room: unpasreurized fruit is loaded with lactobacillis!

He said the contamination has transferred to his old peculiar clone, which doesn't have fruit it in, which is why I would start with the plastic parts in his setup.

Typically the alcohol and hops present are enough to keep the bacteria on fruit at bay, especially if it's store bought stuff. I've brewed tons and tons of fruit beers with fruit from various sources and have never had a bacterial contamination from it (or at least one that's been apparent). A quick rinse of the fruit in starsan is all I've ever done for fresh fruit. Frozen raspberries, strawberries, etc always just go right in to a secondary and then the beer gets racked on top of it.

Now bacterial or wild yeast contamination from me being lazy and not sanitizing my equipment well enough is a totally different story...

 

[bionara]

awesome info, thanks chaps.

Yeah, the buckets were perhaps 1cm apart, and the old P clone blew its lid right when the fruit was underway, so I suspect some ghastlies took a trip round about then. Both of those infected batches have been bottled: I tried the Old P (2 weeks in the bottle) mostly to see how much pressure was in there out of fear alone. It tasted green, a little sour, but had an outstanding head - the best of any homebrew I've made!

I've now a stout in that same bucket (old p clone), and the bucket's been sterilised, dishwashered, and sterilised again before use. I was just curious about dry hopping. The stout is now a week old: is it too late to dry hop? Will dry hopping help prevent any possible infection (no signs of it yet after 9 days primary). Will the hops act as floating life rafts for bacteria to colonise?

As for the fruit, I did stick it in my steamer for 20 mins. I imagine that wasn't enough eh!