Skip to content

SOP — Microbiological Sampling

FUERST WIACEK Version 1.2 | Lab — microbiological sampling | Frequency: per batch, before packaging

Purpose

Microbiological sampling checks the biological stability of beer before packaging. Samples are taken from fermentation tanks using Keofitt sampling bags and sent to VLB Berlin for analysis. Results inform whether a beer is safe to package and track any contamination trends over time.

PPE Required

  • Safety goggles
  • Gloves

Equipment

  • Keofitt sampling bag adapter (two-part)
  • Keofitt sampling bags
  • Caustic bath (shared brewery bath — see Chemical Baths SOP)
  • PAA bath (shared brewery bath)
  • Alcohol spray
  • Small PAA beaker (for carrying between tanks when doing multiple samples)
  • Permanent marker
  • Sample labels

Process

1. Prepare the Adapter — Early in the Day

As early as possible in the day, when you know sampling will happen:

  1. Dip the Keofitt sampling bag adapter into the caustic bath. Leave it there until shortly before use — the longer it soaks, the better.

2. Prepare Bags and Adapter — Before Sampling

When you are ready to sample:

  1. Remove the adapter from the caustic bath. Rinse thoroughly with water to remove all caustic residue.
  2. Dip the adapter and the sampling bags into the PAA bath. Leave briefly to sanitise.
  3. Remove from PAA. Everything is now ready for use — work super-sanitary from this point. Spray connection points and fittings with alcohol before and during assembly. Any contamination here causes a false positive.

Warning

False positives waste a full VLB analysis cycle and can delay packaging. Take your time with the alcohol spray at every connection point.

3. Prepare Sample Labels

For each tank to be sampled, mark a label with:

  • Brewery name: Fuerst Wiacek
  • Beer name
  • Tank number (e.g. GT3)
  • Sample date (e.g. 15.09.2024)

4. Take Samples

Repeat this procedure for each tank.

Assembly:

  1. Connect the back of the sampling bag to the back part of the adapter. Spray the connection with alcohol before joining.

  2. Connect the assembled adapter + bag to the Zwickel on the tank.

    Keofitt sampling bag: adapter connected at the back to the bag, and to the Zwickel. Front of the bag is still untouched.

Pre-rinse:

  1. Open the Zwickel and let beer flow through — rinsing both the Zwickel and the connected bag. This flushes any residual from the port before the actual sample is taken.

Close and collect:

  1. Connect the front part of the adapter to the front of the bag. Make sure all connections are correct and seated properly. Spray with alcohol as you connect.
  2. Using the front part of the adapter, open the bag.

  3. Open the Zwickel carefully and let the bag fill.

    Bag filling — front and back of adapter fully connected, bag being filled through the Zwickel.

  4. 250 ml is more than enough. Once the bag is filled, close the Zwickel and close the bag using the adapter. Make sure the bag is properly sealed.

Post-sample cleanup at the tank:

  1. Rinse the Zwickel and the bag connection point thoroughly with the water spray gun — the same way you rinse the Zwickel after routine beer samples (see Fermentation Monitoring SOP).

  2. Spray down with alcohol.

  3. Fill the Zwickel with alcohol and close it.

Multiple tanks:

Carry a small PAA beaker with you. Between tanks, drop any adapters or fittings into the PAA beaker to keep them sanitised.

5. Label and Store

  1. Label each bag immediately after filling.
  2. Store samples in the cold room.
  3. Arrange same-day delivery to VLB — delay increases the risk of false positives on the report.

6. Notify VLB

When delivery is confirmed, send the notification email before the samples arrive:

To: - biolab@vlb-berlin.org - probeneingang@vlb-berlin.org - production@fuerstwiacek.com - Lukasz@fuerstwiacek.com

Subject: FUERST WIACEK Proben

Body (example):

Hallo zusammen,

wir bringen euch heute 4x Keofitt-Beutel und 5x Dosen vorbei.

Adjust the quantities to match what is actually being delivered.

7. Clean Up

  1. Follow the standard end-of-use parts storage — adapter and fittings into caustic bath, seals into blue container. Next day rinse and transfer to PAA bath.
  2. Return all equipment to its storage location.

Checklist

  • [ ] Adapter placed in caustic bath early in the day
  • [ ] Adapter rinsed with water before use
  • [ ] Adapter and bags dipped in PAA before sampling
  • [ ] Labels prepared — brewery name, beer name, tank number, date
  • [ ] Adapter back connected to bag back — alcohol sprayed before joining
  • [ ] Adapter + bag connected to Zwickel
  • [ ] Pre-rinse: Zwickel opened, beer flushed through bag
  • [ ] Front part of adapter connected to bag front — everything seated correctly
  • [ ] Bag opened via front adapter, Zwickel opened, bag filled to ~250 ml
  • [ ] Zwickel closed, bag sealed with adapter
  • [ ] Zwickel rinsed with water, sprayed with alcohol, filled with alcohol, closed
  • [ ] Samples labelled and placed in cold room
  • [ ] Same-day delivery to VLB arranged
  • [ ] VLB notification email sent before samples arrive
  • [ ] Adapter cleaned: water rinse → caustic → PAA → storage

Troubleshooting

Issue Likely Cause Action
False positive result Contamination during sampling, or delayed delivery Re-sample. Review sampling technique — ensure alcohol spray at every connection. Deliver same day.
Bag not sealing properly Adapter not fully seated Reseat the front adapter piece. Do not use a bag that will not seal — it cannot be delivered reliably.
Zwickel not flowing freely Port partially blocked or pressure too low Open slowly. If no flow, check tank pressure.
Sample port not available Not on shelf or in use Check caustic bath. Ensure port is fully cleaned before using.