Ledger / Semi-hard / 2026-10-19
Jarlsberg Eyes: Twenty Degrees and Salt Under 1.4%
Round holes in a cheese are made by a bacterium that produces gas from propionic acid, and it only works inside a narrow window: warm enough to grow, not salty enough to be inhibited, and with enough residual lactate to feed on. Three conditions, and failing any one gives you a cheese with no eyes or with cracks instead.
Each segment is as wide as its share of the 112 minutes in the vat; the set segment carries the set temperature, the cut segment carries the cut size.
Salt and press drawer
Press ladder
- 6 kg0.5 h
- 14 kg3.5 h
- 20 kg6 h
Applied at 4-8 weeks once the rind is dry. Stops weight loss and stops rind development, so wax late.
Keep the salt under 1.4%
0.5% mixed meso/thermo culture at 34 C, thirty-five minutes of ripening, 22 IMCU of rennet per litre, thirty-five minute set. Cut to 8 mm, scald to 43 C over thirty-five minutes, drain.
Brine at 22% but only for two hours per kilo, less than half the time a Gouda of the same size would take. Target 1.2-1.4% salt in the finished cheese. Above 1.6% the propionic bacteria are inhibited and the eyes never form, no matter how warm the cave is.
Press at 20 kg and hold at 20 C for six weeks
Press at 6 kg for thirty minutes, 14 kg for three and a half hours and 20 kg for six hours, then dry three days at 14 C. Wax, then move to the warm room.
The warm phase is 18-20 C and 85% RH for six weeks. This is the only cheese in this ledger that ripens warm on purpose. At 16 C the eyes form slowly and small; below 14 C they never form at all, and you have made an expensive Gouda.
Read the eyes at six weeks, then cool
Take one wheel and cut a small plug at six weeks. You are looking for round, shiny-walled holes about 10 mm across, evenly spaced and not touching each other. Slits and irregular shapes mean the press was too cold or the curd was too acid.
If the eyes are right, move to 12 C and 80% RH for another six weeks to stop the gas production and set the flavour. Leaving a Jarlsberg in the warm room past eight weeks gives oversized, lopsided holes and a sharp, propionic tang that overpowers everything else.
Wax again and rest, then eat at twelve weeks
Re-wax after the warm phase, because the original coat will have stretched over the swelling wheel and may have split. A split coat lets air in and the eyes nearest the split go grey.
Eat at twelve weeks for a mild, nutty cheese with a clean finish. At six months the flavour turns distinctly caramel and the eyes collapse slightly; that is also traditional, and the Norwegians call the two versions by different names.
Aging parameters
| Milk | Pasteurised cow milk 3.5% fat |
|---|---|
| Culture | Mixed meso/thermo 30–42 °C |
| Rennet | Calf rennet (animal) 22 IMCU/L |
| pH at drain | 6.5 target 6.1–6.5 |
| Target moisture | 40 % |
| Cave temperature | 18 °C |
| Cave humidity | 85 % |
| Aging days | 90 days |
| Rind treatment | Wax |
| Yield | 3.9 kg |
Pasteurised cow milk Semi-hard 90 days
Defect diagnosis
Flagged on this make: Faulty eye formation、Bitterness
Bitterness seen this make
Signal — A harsh, lingering bitter note at the back of the palate, strongest in the first three weeks and often fading after six.
Cause — Too much rennet for the set time, or a microbial coagulant with high protease activity, or a scald that never got past 38 C.
Fix — Cut the dose by 20% next make and hold the scald 2 C higher for 10 minutes longer. Bitter peptides are water-soluble, so a 12% brine for 24 hours pulls some out.
Rancidity not seen
Signal — Soapy, paint-like smell that hits before the cheese reaches the mouth. Sharp and unpleasant rather than merely strong.
Cause — Free fatty acids released by lipase, usually from raw milk that sat warm too long, or from rennet paste, or from a knife or cloth that carried old milk residue.
Fix — Chill milk to 4 C within two hours of milking and pasteurise anything older than 24 hours. Retire the cloth: boil it, do not just rinse it.
Faulty eye formation seen this make
Signal — Either no eyes where the style demands them, or a scatter of irregular slits and cracks instead of round, evenly spaced holes.
Cause — Coliform or yeast contamination from unsanitary brine, or a press that was too cold (below 18 C) so the propionic culture never woke up, or too much salt killing it outright.
Fix — Boil and re-salt the brine to 18-20% between batches, press at 20-22 C for the first six hours, and keep the salt under 1.6% for eye-forming styles.
Misread surface mould not seen
Signal — A grey-green or black fuzzy patch on a rind that was supposed to be white or orange, or blue speckling on a hard cheese.
Cause — Wild Penicillium and Cladosporium from a cave with moving air and standing humidity. Also from brushing a good rind with a damp, dirty brush.
Fix — Distinguish before you discard: white felt and orange smear are wanted, green fuzz on a hard rind is surface only and rubs off with 3% brine. Black patches that pit the paste mean the wheel is lost.
Four things to carry forward
- Keep salt at 1.2-1.4%: propionic bacteria stop above 1.6%
- Brine at 22% but only two hours per kilo
- Warm room at 18-20 C for six weeks, then 12 C for six
- Re-wax after the warm phase; the first coat will have split