Metallic/Tannic Taste - StarSan & Plate Chiller?

[ultravista]

I've been getting a slight metallic/tannic taste in all of my beers.

My process has been ...

Sanitizing my 30 plate chiller with StarSan, I typically let the solution sit in the chiller for 30 to 45 minutes, drain, then refil with the same solution. I noticed the last time that the StarSan exiting the chiller was cloudy and not clear as it went in. Using distilled water, my StarSan is crystal clear. Only does it change when it runs through the plate chiller.

I met with a commercial brewer today who tasted my beers and confirmed a slight metallic/tannic taste. Nothing over the top, but present.

When discussing my cleaning, he felt that my sanitizing process may be the root of the problem. That by leaving the StarSan in the plate chiller it was altering the pacification and that by immediately using the chiller, without allowing the pacification to reform, may be allowing the hot wort passing through it to pickup some of the metallic taste.

It was suggested that the plate chiller did not have time to repacificy.

Does this make any sense?

Will a solution of StarSan somehow strip the protective pacification from the inside of the plate chiller? If so, how do I repacify?

[Kbar]

Had this issue in the first 4 batches of beer after I went to my new 30-plate CFC. I simply eprfored an overnight soak with PBW and hot water, then a flush loop with starsan (CIP). Have to imagine they are not the cleanest coming out of the manufacturing facility.

[BDawg]

Before going further, I'd try a splitting a batch into 2 vessels postboil, and chilling 1/2 with another chiller (like an immersion chiller) then comparing them side by side to be sure that the plate chiller is the problem.

Nitric acid is what is used to pacify stainless steel.

Here are a couple other ideas to get you started:

You should contact the manufacturer and see what they say about starsan (phosphoric acid) being run through it like you have been doing.

Also look for any and all non-Stainless Steel metals anywhere in your post-fermentation racking/packaging equipment. You may have some brass or copper somewhere. The best route is to replace them with stainless.

HTH-

[ajdelange]

Pacification is what we'd like to do to North Korea. Passivation is what we want to do to stainless steel. Passivation is accomplished when the metal oxidizes. Nitric acid is used as a passivating agent because it is an oxidizing agent but exposure to the air will do the job as well if not as fast.

I don't know much about metallurgy so can't really comment on whether phosphoric acid would remove passivation. Metal oxides do dissolve in acids on the one hand but it is (or was) common practice to remove beer stone from stainless equipment with a mix of phosporic and nitric acids with the explanation for the nitric being that it was there to oxidize the protein so that the phosporic could dissolve the oxalate but perhaps the nitric was also there to repassivate the steel. I clean my ferementers and kegs this way and have no problems with metallic tastes in the beer.

The chiller, OTOH, I clean with caustic and sanitize with iodophor and do not experience any off flavors. In this case I would recommend going through the normal cleaning and sanitizing protocol followed by passage of hot water through the chiller. Taste the exiting water from time to time. If the water tastes funny beer will taste funny too. Note how much water it takes to rinse the funny taste out of the chiller and then use at least that much water to rinse before you brew. If the rinse water does not taste metallic then the chiller is not the source of the problem

I will note that wort chillers build up a lot of junk inside. In my own practices I rinse thoroughly with hot water after each brew session. This water exits the chiller clean. Before the next brew I circulate hot caustic which turns the most remarkable color and frees a lot of tiny flakes of black material (which get picked up by the strainer screen on the recirculating pump inlet). IOW clean rinse water does not mean the chiller is indeed clean. The caustic treatment is followed by lots of water i.e. enough to get all the caustic out. Then on brew day I recirculate iodophor through chiller, hoses etc and finalize by rinsing the system with boiling water to get the iodophor out. The wort then pushes the rinse water out. So you might want to experiment with iodophor. It definitely does not lead to the problem you are describing.

[ultravista]

I feel that I cleaned the chiller pretty well before the first use. I have used PBW after two or three brews.

Something is altering the PH while it passes through the chiller. I'll have to find some PH strips to test the in vs. out. As I mentioned, the solution is clear before entering the chiller and cloudy upon exit.

I do flush and reverse flush after use. Even with a stout, the runnings are pretty clear very quickly.

I mash in a voile bag and hop in a .2 micron filter bag. The wort is clean, with the exception of hot break/protiens derived from the boil.

There is no metal past the chiller with the exception of the stainless keg itself.

[sharkguy05]

I would say clean it well with pbw then bake it or run boiling water thru for 15 min that will kill anything off and help break up and flush any gunk stuck inside

[sharkguy05]

I would say clean it well with pbw then bake it or run boiling water thru for 15 min that will kill anything off and help break up and flush any gunk stuck inside

[Cliff]

Hmmm Star San stripping away the chrome oxide passive layer from your SST.

Dunno of this will happen. Some food acids will etch the passive layer many won't.
What you might do is contact Five Star Chemicals and ask.
They've got a customer Support email on the main page


Meanwhile if you are concerned passivate your SST:
Get yourself some Citric acid you can get cheap kosher citric on the flea bay. Make a solution of it with plain tap water and if you have any EDTA toss some in, but the EDTA is not necessary. The solution strength is relay irrelevant: Stronger is faster. Also temperature i irrelevant: warmer is faster.

The EDTA merely binds to any iron that is liberated and prevents it from redepositing on the surface. It binds nonspecifically to all minerals.
A larger volume of fluid accomplishes the same thing by dilution instead of affinity bonding.

Yah you could use Nitric, but you gotta have the titration just right (down to the millimolarity) and the water has to be distilled and the temp has to be closely controlled and you gotta watch the time closely. Citric acid is a vastly better passivation medium, especially for the hobby brewer.