What You Need to Know
Rennet contains chymosin (EC 3.4.23.4) which specifically hydrolyzes Phe105-Met106 bonds in κ-casein, removing the hydrophilic macropeptide and exposing hydrophobic para-κ-casein. This allows calcium-mediated crosslinking of casein micelles. Microbial alternatives use Mucor miehei protease (EC 3.4.23.23) with similar specificity.
Essential for hard cheeses like Parmigiano-Reggiano where strong curd structure is needed for aging. Produces cleaner break than acid coagulation, with less moisture retention. Traditional animal rennet from calf abomasum is being supplemented with fermentation-produced chymosin (FPC).
Key Parameters
Temperature
°C - °C
Time
30-45 min
20 min - 60 min
Equipment
Stainless steel vatCurd knifepH meterWater bath for temperature control
Steps
- 1.
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- 2.
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The Science
Primary Reaction
Proteolytic cleavage of κ-casein