Several possible causes:
• Use of semi-skimmed or skimmed milk without adding milk powder (the milk used on its own is not rich enough in proteins). → Add 1 yoghurt jar of milk powder (2 with skimmed milk) or use whole milk and a half a jar of whole milk powder.
• The yoghurt maker was moved, bumped or vibrated during fermentation. → Do not move the yoghurt maker while it is working (do not place it on a refrigerator).
• The ferment is no longer active. → Change ferment or brand of yoghurt. Check the use-by-date of your ferment or your yoghurt.
• The yoghurt maker was opened during its fermentation cycle. → Do not remove the jars or open the yoghurt maker before the programme is finished (around 8 hours). Keep the yoghurt maker out of draughts while it is operating.
• Fermentation time too short. → Start a second cycle at the end of the first.
• The pots haven’t been properly cleaned/rinsed. → Before pouring your preparation into the pots, check that there are no traces of washing-up liquid, household cleaner or dirt on the inside of the pots.
• Fruit added to the yoghurt. → Try cooking fruits, or preferably use commercial stewed fruits or jams (at room temperature). Raw fruits will release acidic substances which prevent the yoghurt from forming correctly.
• Use the milk and ferment at room temperature or slightly warm (heat to 37°C or 40°C and measure using a thermometer). Do not use milk straight out of the refrigerator.