And here it comes. The old - did you check everything? I though I did. The 'How did it go sheet' tells a different story.
The ripening stage went well based on the pH reading a .08 drop in 90 minutes was awesome. Added the rennet and there my doubts started. Usually, 8 liters will hit the flocculation point in approx. 10 minutes and this time went to 14 minutes. This is on the upper edge of acceptable. So, okay, the floc point was a bit slow and the rennet was still within the date range. My brain was going through all the possible reasons. Suspect milk, calibration error on the pH meter or batteries, old culture, temperature fluctuations all were candidates. The Floc point of 14 minutes added another 24 minutes to the cut time calculation using a floc multiplication factor of 6.
This gave me time to check all the interrogate all the suspects. I changed the pH meters batteries, refreshed the calibration fluid and recalibrated the meter. I checked both the Digital and mechanical thermometers at Boiling and freezing points and both were within tolerances. Rummaged through the recycling bin and checked the empty milk bottles and they were all from the same batch and had 11 days on the useby date. I rechecked expiry dates and there I found a sleeping agent - the best before batch date on the Flora Danica Oct 2015. Ouch! I used this same culture when I was making the Taleggio a couple of weeks ago but that was with a couple of other Messo Cultures.
The evidence was borne out at the next pH check points - after the Curd Cut, stirring for 15 minutes and resting for 15 minutes phases.