# Why would PBW extract lots of colour from hops?



## Mr. No-Tip (8/7/13)

Let me preface this by saying that I realise the ridiculousness of this thread title. Why would you let PBW pass hops? I wanted to do a test run of my brown pump and hop rocket without risking a brew, so grabbed some low value (but not old and still very green) hops and test pumped it at cleanup time.

The PBW had soaked in my kettle overnight and was reheated to 90 degrees - it's not crystal clear, but far from brown:





What came out of the pump/hop rocket/kettle combo was a while other story:




It wasn't as dark as it appears in this photo, but very much like a dark IPA colour. I eliminated both the pump and chiller as the source of the colour - my chiller was cleaned yesterday and the dark colour was clear in the hose upstream from the chiller. The pump was new and never used, but no amount of loose oil or whatever in the new brown pump could do this. I also tried the PBW direct on some new hops in a jar to compare - same thing - not quite as dark as the pumped version but still darker than I'd expect.

Then I tried it with hot water of a similar temperature:




Much greener, less brown, as expected.

And the spent hops side by side - notice the reddish tinge to the PBW hops:




Obviously this has no practical relevance in brewing, but the whole thing did intrigue me. Why is this happening? Something to do with the alkaline in PBW?


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## Florian (8/7/13)

The only guess or hint I have is that hops (or most plants for that matter) turn brown when they die off or dry out. So the alkalinity or some other chemical reaction from the PBW might cause a similar effect that happened on a dead plant?

Are dead plants more alkaline than alive ones?


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## Ducatiboy stu (8/7/13)

Oxidisation


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## Florian (8/7/13)

Doesn't explain his hot water experiment, though.


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## pk.sax (8/7/13)

Doesn't it? His hot water one was barely green... Compared to the pbw one.


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## Florian (8/7/13)

He is looking for an explanation for the brown though, not the green.
The hot water hop was not brown like the PBW one, but would have had the same amount of oxidisation happening (refer jar comparison).


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## pk.sax (9/7/13)

Ah, I thought stu meant oxidised by pbw releasing oxygen.


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## Ducatiboy stu (9/7/13)

Florian said:


> He is looking for an explanation for the brown though, not the green.
> The hot water hop was not brown like the PBW one, but would have had the same amount of oxidisation happening (refer jar comparison).


Um.....er...no.... Wouldnt the PBW oxadise a lot more than water....


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## Florian (9/7/13)

Um.....er...yes.... Maybe. Didn't think of the oxygen release thing.


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## Mr. No-Tip (9/7/13)

So the 'oxy action' of PBW oxidised the hops? Interesting.


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## Florian (9/7/13)

Possibly.


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## Whiteferret (9/7/13)

Didn't you leave the PBW in overnight? How long will the oxygen keep coming out?


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