Blue Cheese

Introduction

The origin of mould ripened cheese is lost in antiquity. It was made in France at least as early as the Roman era. The name" Roquefort" first appeared in the year 1070. Roquefort cheese is made from ewes' milk, and the trade name is protected throughout the world. Other cheese varieties that are ripened by the mould Penicillium roqueforti include Blue (Bleu, Blue-veined), Gorgonzola (Italy), Stilton, Wensleydale and Dorset Blue (Blue Vinney) of England, Niva of Czechoslovakia, Danablu and Mycella of Denmark, Nuworld, U.S. and Errmite, Canada. P. roqueforti has been known by other names such as P. glaucum, P. gorgonzola and P. stilton. A white mutant of P. roqueforti was developed by Knight of Wisconsin and the resulting cheese is called Nuworld.

Standards: 47% moisture; 27% fat. In practice, the fat content is usually higher.

Procedure

  1. Pasteurize milk. P/F ratio of about 0.87 is desirable. Milk may also be homogenized before pasteurization to promote lipolysis in the cheese. If the milk is not homogenized, add 30 g lipase per 1,000 kg of milk. If the milk is highly coloured, 0.03 - 0.04% titanium dioxide diluted with 10x its weight of warm water may be added to the milk before renneting, to prevent green cheese.
  2. Add 3% mesophilic lactic starter and ripen for about an hour at 32C until TA increases by at least 0.05% and pH is 6.6 - 6.5
  3. Measure 200 ml rennet per 1,000 kg milk (dilute rennet about 20 times with water and add to the milk). Setting will occur in 20 - 30 min. but do not cut until 1 hr. after renneting.
  4. Cut curd with Omega" (12.8 mm knives). Allow curd to settle for 10 min. then agitate gently to prevent matting. When the acidity is 0.02% above cutting acid (about 80 min. after cutting) push curd away from the gate and allow it to settle for 10 min.
    [Feta cheese can be made from the same vat as Blue cheese, by dipping some of the curd and whey into rectangular forms when the acidity is about .01% above cutting acid (20-40 min after cutting), and then proceeding from Step 7 in the Feta procedure above. Similarly, Camembert cheese can be made by removing some curd and whey at 45 - 60 minutes after cutting
    and proceeding from Step 5 in the Camembert procedure above.]
  5. Remove whey to the level of the curd. Break up curd and remove remaining whey. Ditch curd and turn over after 10 min. After an additional 10 min. break up the curd to prepare for salting.
  6. Add salt, 1% of weight of curd. Sprinkle blue mould powder (Penicillium roqueforti over all the curd. It should look like well peppered scrambled eggs. Mix the mold powder thoroughly, and then place curd in cylindrical hoops on a drain table. Be certain that blue cheese is kept well apart from other cheeses in the make room.
  7. Turn cheese 5 - 10 min. after filling and then at 30 min. intervals for 2 Omega hrs. Cover with broad cloth and incubate overnight at room temperature for 16 - 20 h or until cheese pH is 4.5 - 4.7.
  8. Weigh sufficient salt to provide 50 g of salt per kg of cheese. Salt the cheese by rubbing the salt on all surfaces. Store the cheese at 85% RH and 12 - 14C for 24 h, or place the cheese on plastic mats in large plastic tubs with the lids partially open to allow some drying off of the cheese, and store at 12 - 13C for 24 h.
  9. If desired, the cheese can be treated with paraffin (waxed) before skewering and ripening. Alternatively, the cheese may be turned and brushed regularly while curing (Step 11) to encourage development of smear on the surface.
  10. Put about 60 holes on both sides of each cheese with a 3 mm diameter skewer.
  11. Store the cheese at 95% RH and 12 - 14C for 6 - 8 weeks. Alternatively, the cheese can be placed on plastic mats in large plastic tubs with the lids slightly open to allow some oxygen entry for mould growth, and ripened at 12 - 14C. Turn every day for several days and then turn once a week. The pH should increase to 6.0 - 6.25 after 8 weeks.
  12. Vacuum pack and store at 7C until consumed (up to 3 months).

Curing

Few lactic starter bacteria survive the first few weeks of curing due to acid and salt inhibition. P. roqueforti becomes evident 8 - 10 days after pricking. This mould grows well because it is more tolerant of salt and low oxygen than other moulds. The smear which forms on the surface is due to B. linens or B. erythrogenes. Too much smear is undesirable.

Activities of mould lipases and added lipases produce butyric, caproic, caprylic, capric and higher fatty acids. A predominant flavour compound is methyl-n-amyl Ketone (heptanone 2).

Caprylic acid CH3(CH2)6.COOH

Methyl-n-amyl Ketone CH3(CH2)4.COCH3