Chymosin is also generally called rennin because it is easily confused with renin. The International Committee of Enzymology recommends the use of this name, namely chymosin, also known as rennet, Chymogen, Lab (German), and remnase. It is a protease.
As one of Food Grade Enzymes, Rennet is an indispensable preparation for cheese production, and its output value accounts for 15.5% of the total output value of enzyme preparations. The main source is the gastric mucosa of unweaned calves.
The Specification of Rennet:
| Name: |
Chymosin |
CAS: |
9042-08-4 |
| Specification: |
5000-30000u/g |
Other Name: |
Rennin, Rennet |
| Shelf Life: |
24 Months |
Grade: |
Food Grade |
| Certificate: |
COA MSDS |
Sample: |
10-20g |
Rennet - Functions and Types
1. Function: Promote the coagulation of raw milk and provide conditions for the discharge of whey.
2. Type
Rennet is available in three forms: liquid, powder and tablets. Traditionally, chymosin is extracted from the abomasum of the fourth stomach of calves. Recently, the sources of chymosin have been expanding and currently include three categories: animal chymosin, derived from cow stomach, pig stomach and sheep stomach; plant-based chymosin Rennet, derived from fig sap and pineapple fruit; microbial rennet, derived from molds and yeasts. Rennet derived from molds is widely used in Danish cheese production.
3. Activity of Chymosin
It refers to the number of milliliters of raw milk that 1 ml of rennet solution or 1 gram of dry powder can coagulate in 40 minutes at 35°C. The activity of standard liquid rennet is usually 12,000-15,000, while the activity of powdered rennet is 10 times the former, at 120,000-150,000.
4. Raw milk Coagulation Process
There are three types of casein in raw milk: αs-casein, β-casein and К-casein. The former two are susceptible to the influence of Ca+2 to form precipitation, while the latter is not only stable, but also has the effect of inhibiting the precipitation of the former. Rennet coagulates raw milk in two stages: first, it decomposes K-casein into para-K-casein; secondly, para-K-casein, αs-casein and β-casein are precipitated under the action of Ca+2.
Chymosin-Factors Affecting Chymosin Activity
(1) PH: The activity of rennet is strongest in an acidic environment. Any slight change in the acidity of raw milk can significantly affect the activity of rennet. Most of the activity of chymosin comes from trypsin, and a small part comes from bovine pepsin (but the active ingredient in porcine chymosin is porcine pepsin). The optimal pH of trypsin is 5.4, while the optimal pH of pepsin is lower than trypsin.
(2) Temperature: The optimal temperature of rennet is 42°C. (At 55-60°C, the enzyme itself is destroyed) because the milk temperature significantly affects the coagulation speed. When the milk temperature is 30°C, the coagulation time of raw milk is 2-3 times that of 42°C. However, in actual cheese production, the milk temperature is usually maintained at 30-33°C. First, the optimal temperature of lactic acid bacteria is taken into account (for example, the optimal temperature of Streptococcus is around 30°C, and the maximum temperature cannot exceed 40°C); second, the higher milk temperature The clot hardens too quickly at low temperatures, making subsequent cutting difficult.
(3) Ca+2 concentration: Casein converted by chymosin can coagulate only when there are free calcium ions in the raw milk. Calcium ion concentration will therefore affect clotting time, clot hardness and whey drainage.
Rennet-Added Amount
The usual dosage is 20-40 ml of rennet solution added to 100kg of raw milk. The curing time is inversely proportional to the dosage of rennet. If the dosage is doubled, the curing time will be halved.
The discharge of whey is not affected by the dosage of rennet. Experiments show that the dosage of rennet has nothing to do with the moisture content and PH quality of the cheese after 24 hours. However, the dosage affects the ripening of cheese. If the dosage is large, the decomposition of protein during the ripening period will be accelerated. At the same time, because rennet decomposes protein to produce bitter peptides, large dosage will also increase the bitterness of cheese.
