Source of infection

[calebgk]

My past several batches have been mildly infected. I say mildly because I've only dumped a few of them, and choked down the others. Cloudy, funky sweet flavor, pellicle in FV.

I've changed hoses, disassembled and cleaned ball valves. IC goes in 15 minutes left in boil. Changed FVs.

I'm starting to think it might be my mash paddle. Just some softwood paddle I got from homebrew shop. Post-boil, if I'm whirlpooling with it, I spray it with StarSan.

Any chance it is the paddle? I'm thinking of hitting up Eastern Shores this weekend for a SS paddle, anyways.

Any other directions I should look to clean up my act?

 

[SiriusStarr]

What do you use for fermentation? Carboys or buckets? If you have that tenacious of an infection problem, I would say pitch everything plastic that touches your wort after the boil, e.g. buckets, racking cane, tubing, etc. I personally wouldn't use a wooden paddle to touch the wort post-boil; you can't really sanitize wood, since it's a rough, organic surface. (Thus the same problem as wooden cutting boards.)

 

[progmac]

Plastic bucket is the most obvious source
Don't use anything wooden after the boil, wood is basically unsanitizable

 

[calebgk]

All buckets. I just gravity feed from kettle into bucket. I used to catch the trub in a sanitized mesh bag, but stopped doing that, thinking it was a contributing factor. I'm going to turf the paddle and get something stainless. Perhaps my next few batches, I'll primary in carboys, see if that helps.

 

[EarlyAmateurZymurgist]

How do you handle your yeast culture? Ninety-nine percent of all beer infections can be traced to improper yeast culture handling. If one's yeast culture is clean, healthy, and properly pitched, any house microflora that is picked up during the handling of the wort doesn't stand a chance of gaining a foothold in one's fermentor.

 

[butterpants]

I vote: BURN THE WOODEN PADDLE

 

[duboman]

How do you handle your yeast culture? Ninety-nine percent of all beer infections can be traced to improper yeast culture handling. If one's yeast culture is clean, healthy, and properly pitched, any house microflora that is picked up during the handling of the wort doesn't stand a chance of gaining a foothold in one's fermentor.

Really? 99%? After reading of myriads of infection issues from primary to finished beer in kegs and bottles I'm curious if you have something to back this up?

To the OP, trash the paddle or quit using it to stir your wort post boil. Check your buckets for scratches and the inside lip of the lid for stains. If there is a valve on it, remove and replace it. also look at the bung and airlock and what you are putting in the airlock during fermentation. Replace transfer tubing and evaluate your racking cane and anything else that touches the beer or wort.

If infections are occurring with packaging then you need to do the same meticulous investigation of everything that is coming in touch with your finished product and be sure you are diluting the Star San to the proper mix and not too light.

 

[day_trippr]

Really? 99%? After reading of myriads of infection issues from primary to finished beer in kegs and bottles I'm curious if you have something to back this up?[...]

 

[EarlyAmateurZymurgist]

Really? 99%? After reading of myriads of infection issues from primary to finished beer in kegs and bottles I'm curious if you have something to back this up?

It's simple biology. I have posted this information before, but I will post it again because so few amateur brewers understand how critical it is to handle one's pitching yeast properly.

Fermentation is little more than controlled spoilage. On average, bacteria cells divide every thirty minutes whereas yeast cells divide every ninety minutes; therefore, one needs to pitch enough clean yeast to out-compete any other microflora that may be introduced to one's wort. Cell division follows an exponential growth pattern. The increase in cell count for yeast can be calculated as:

initial_cell_count * 2^(elapsed_time_in_minutes_since_the_start_of_the_ growth_phase / 90), where the symbol "^" denotes raised to the power of.

Examples

Cell count after 90 minutes of growth

initial_cell_count * 2^(90 / 90) = 2 x initial_cell_count


Cell count after 6 hours of growth

initial_cell_count * 2^(360 / 90) = 16 x initial_cell_count


There is a period between pitching and the growth phase (a.k.a. exponential or log phase) known as the lag phase. The lag phase is where the yeast cells that were pitched prepare themselves for growth.

When a batch is under-pitched or one pitches an infected yeast culture, the situation gets ugly really quickly. Let's track yeast versus bacteria growth over time.


Yeast Cell count after 90 minutes of growth

initial_yeast_cell_count * 2^(90 / 90) = 2 x initial_yeast_cell_count

Bacteria Cell count after 90 minutes of growth

initial_bacteria_cell_count * 2^(90 / 30) = 8 x initial_bacteria_cell_count


Yeast Cell count after 6 hours of growth

initial_yeast_cell_count * 2^(360 / 90) = 16 x initial_yeast_cell_count

Bacteria Cell count after 6 hours of growth

initial_bacteria_cell_count * 2^(360 / 30) = 4,906 x initial_bacteria_cell_count


Yeast Cell count after 12 hours of growth

initial_yeast_cell_count * 2^(720 / 90) = 256 x initial_yeast_cell_count

Bacteria Cell count after 12 hours of growth

initial_bacteria_cell_count * 2^(720 / 30) = 16,777,216 x initial_bacteria_cell_count


Yeast Cell count after 24 hours of growth

initial_yeast_cell_count * 2^(1440 / 90) = 65,536 x initial_yeast_cell_count

Bacteria Cell count after 24 hours of growth

initial_bacteria_cell_count * 2^(1440 / 30) = 281,474,976,710,656 x initial_bacteria_cell_count


The single biggest improvement that an amateur brewer can make is to learn how to properly handle and propagate yeast. Yeast is the most important ingredient in beer. The off-flavors produced when one pitches too little yeast are more often than not caused by house microflora that established a foothold at the beginning of fermentation. It is darn near impossible for house microflora to establish a foothold in wort that is pitched with a properly handled yeast culture. The numbers are not in the house microflora's favor. The pitching yeast will divide fast enough that it will consume all of the available oxygen in the wort; thereby, cutting off aerobic bacteria. The pitching yeast will also lower the pH and start to produce alcohol after it switches from respiration to fermentation; thereby, cutting off anaerobic bacteria growth.

 

[tnlandsailor]

I would hate to encourage the amateur brewing community to go slack on their post-boil sanitation in regard to wort handling. This might be one of those cases where, in theory, theory and practice are the same, but not in practice. The numbers do tell a story, and it certainly makes sense. In fact, it's downright encouraging if the take-away from it is that our sanitation practices from a wort handling stand point are not as important as we thought they were. But I just don't think it works out that way. I think it's easier to handle a small 2 liter starter and keep it sanitary, than to boil, chill, drain, and oxygenate 5 gallons of beer while keeping it sanitary.

This would make an interesting experiment. Brew a 10 gallon batch and split it using the same starter in each one. In one batch, do something like forget to sanitize the carboy, or use unsanitized hoses for transferring. In the other, follow standard sanitation protocol. If they both turn out fine, we have a new way to look at sanitation. If not, perhaps that 99% number is a bit overstated.

For what it's worth, I have a friend who keeps a scrupulously clean brewery. He uses PBW on his glass fermenters right before sanitizing them on brew day and inspects each one thoroughly for any stray spots before sanitizing. One day, on a split batch, he began filling a carboy that he realized had been cleaned with PBW and rinsed, but not sanitized. It was too late to do anything so he finished out and fermented both carboys (the other carboy was sanitized). Both turned out with no infection. Was it the PBW that cleaned "good enough", or did the yeast vs. bacteria theory prove out? I have no idea, but I tasted the beer myself and it was fine.

 

[aiptasia]

No matter what you do or how careful you are, SOME bacteria are going to get into the wort. We're not brewing in sterile environments, just sanitized environments. The goal is to "infect" the wort with a fungus (yeast) before other organisms have a chance to dominate the wort. To do this, you should properly sanitize anything that comes into direct contact with the wort to reduce foreign bacteria and fungus and nurture the yeast properly with the right amount of food, oxygen and nutrients to effectively ferment the wort while dominating everything else to a negligent impact on the finished beer.

This means both arguments above are correct at the same time: You need healthy, vigorous yeast and a sanitary environment for them to dominate the wort.

IMHO, i'd ditch the wooden mash paddle and review my sanitation regimen. I'd disassemble and inspect my equipment for sources of potential infection and clean everything with PBW and Star-San. Don't forget to remove gaskets and o-rings and clean/sanitize those areas as well. Some nasty trub can get stuck under the o-rings around fermentation bucket lids. Never use anything more abrasive than a cloth or paper towel when scrubbing plastic. Inspect your equipment for scratches and abrasions. Replace them if you notice anything abrated or damaged.

Also, if you're adding anything to the wort such as adjuncts, dry hops or top off water, you figure out a way to sanitize those as well. Top off water needs to be boiled or use distilled bottled water, hops bags should be soaked in star san or idophor, wood chips need to be baked at 200f for a little bit or steam heated in a microwave, etc.

 

[duboman]

It's simple biology. I have posted this information before, but I will post it again because so few amateur brewers understand how critical it is to handle one's pitching yeast properly.

Fermentation is little more than controlled spoilage. On average, bacteria cells divide every thirty minutes whereas yeast cells divide every ninety minutes; therefore, one needs to pitch enough clean yeast to out-compete any other microflora that may be introduced to one's wort. Cell division follows an exponential growth pattern. The increase in cell count for yeast can be calculated as:

initial_cell_count * 2^(elapsed_time_in_minutes_since_the_start_of_the_ growth_phase / 90), where the symbol "^" denotes raised to the power of.

Examples

Cell count after 90 minutes of growth

initial_cell_count * 2^(90 / 90) = 2 x initial_cell_count


Cell count after 6 hours of growth

initial_cell_count * 2^(360 / 90) = 16 x initial_cell_count


There is a period between pitching and the growth phase (a.k.a. exponential or log phase) known as the lag phase. The lag phase is where the yeast cells that were pitched prepare themselves for growth.

When a batch is under-pitched or one pitches an infected yeast culture, the situation gets ugly really quickly. Let's track yeast versus bacteria growth over time.


Yeast Cell count after 90 minutes of growth

initial_yeast_cell_count * 2^(90 / 90) = 2 x initial_yeast_cell_count

Bacteria Cell count after 90 minutes of growth

initial_bacteria_cell_count * 2^(90 / 30) = 8 x initial_bacteria_cell_count


Yeast Cell count after 6 hours of growth

initial_yeast_cell_count * 2^(360 / 90) = 16 x initial_yeast_cell_count

Bacteria Cell count after 6 hours of growth

initial_bacteria_cell_count * 2^(360 / 30) = 4,906 x initial_bacteria_cell_count


Yeast Cell count after 12 hours of growth

initial_yeast_cell_count * 2^(720 / 90) = 256 x initial_yeast_cell_count

Bacteria Cell count after 12 hours of growth

initial_bacteria_cell_count * 2^(720 / 30) = 16,777,216 x initial_bacteria_cell_count


Yeast Cell count after 24 hours of growth

initial_yeast_cell_count * 2^(1440 / 90) = 65,536 x initial_yeast_cell_count

Bacteria Cell count after 24 hours of growth

initial_bacteria_cell_count * 2^(1440 / 30) = 281,474,976,710,656 x initial_bacteria_cell_count


The single biggest improvement that an amateur brewer can make is to learn how to properly handle and propagate yeast. Yeast is the most important ingredient in beer. The off-flavors produced when one pitches too little yeast are more often than not caused by house microflora that established a foothold at the beginning of fermentation. It is darn near impossible for house microflora to establish a foothold in wort that is pitched with a properly handled yeast culture. The numbers are not in the house microflora's favor. The pitching yeast will divide fast enough that it will consume all of the available oxygen in the wort; thereby, cutting off aerobic bacteria. The pitching yeast will also lower the pH and start to produce alcohol after it switches from respiration to fermentation; thereby, cutting off anaerobic bacteria growth.

So I hate to bump this thread but I felt I needed to do my own research before replying since I questioned the validity of the claim:

Your math makes sense, but only if you assume that there is so much extra yeast and so few bacteria, as well as no "extra" nutrients available for anything else to thrive on. Also, these are optimum growth models and don't account for the fact that not every yeast/bacteria will reproduce, that some die, and that bacteria could be feeding on the yeast themselves (couldn't find a study, but the biology makes sense). Also, here's a link to a variety of anaerobic bacteria species that have been shown to live in the high alcohol, low pH, high CO2 environment of the wort. http://maltingandbrewing.com/beer-spoilage-organisms.html Here's a link to an abstract of a scientific article for an over view of beer spoilage http://www.sciencedirect.com/science/article/pii/S0168160503001533 and one that is looking to develop antimicrobials to prevent beer spoilage, which means that the bacteria can live through the process http://www.sciencedirect.com/science/article/pii/S0168160508001955 This last one is a study trying to pinpoint which of the species of a certain anaerobic bacteria is causing spoilage http://www.sciencedirect.com/science/article/pii/S0168160596012068

So basically I am not completely disputing the claim of simple biology more so than simply stating that even with proper pitch and yeast health there still remains a possibility that infected batches can still occur in an otherwise perfect environment.

 

[day_trippr]

 

[EarlyAmateurZymurgist]

So I hate to bump this thread but I felt I needed to do my own research before replying since I questioned the validity of the claim:
<snip>
So basically I am not completely disputing the claim of simple biology more so than simply stating that even with proper pitch and yeast health there still remains a possibility that infected batches can still occur in an otherwise perfect environment.

While not impossible, the probability that the average home brewery will experience a resistant type of infection is very low. Commercial breweries are completely different animals. They are like hospitals in that they constantly kill off weaker microflora leaving only the most resistant microbes behind. A homebrewery has a more natural balance of microflora.