Bushra Griffith
Chymosin is a protease found in rennet, which is used in cheese production to curdle milk. Historically, chymosin was obtained from the stomachs of slaughtered calves, but today, most commercial chymosin is produced recombinantly in bacteria, fungi, or yeast. This recombinant chymosin has been used to produce a variety of cheeses, including cheddar, Colby, and soft white cheese made from camel milk. The use of recombinant chymosin offers several advantages, such as improved efficiency, higher purity, and the absence of GM components. It is also useful for producing cheese from milk with lower casein content, such as camel milk, as it aids in coagulation and results in higher cheese yields.
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What You'll Learn
- Recombinant chymosin is used to make white soft cheese from camel milk
- Recombinant chymosin is potentially useful in cheesemaking and may replace animal-derived enzymes
- Bovine chymosin is the preferred enzyme for high-quality cheese production
- Commercial chymosin is produced recombinantly in Escherichia coli, Aspergillus niger, and Kluyveromyces lactis
- Recombinant chymosin has been used to produce a variety of cheeses
Recombinant chymosin is used to make white soft cheese from camel milk
Chymosin is a protease found in rennet and is used in cheese-making to induce curd formation. Historically, chymosin was obtained from the stomachs of slaughtered calves. However, due to the imperfections and scarcity of animal rennet, producers turned to recombinant chymosin, which is now widely used in commercial cheese production. Recombinant chymosin is produced through genetic engineering by extracting rennet-producing genes from animal stomachs and inserting them into bacteria, fungi, or yeast. This process allows for the large-scale production of chymosin without the need for animal sources.
Camel milk is known to have higher amounts of beta-casein, making it similar to human milk and easier to digest. It also lacks β-lactoglobulin, a potential allergen for infants. However, bovine-derived chymosin in rennet cannot coagulate camel milk, making it challenging to process into cheese. This is where recombinant camel chymosin comes into play.
Recombinant camel chymosin has been successfully used to make white soft cheese from camel milk. The process involves preparing pasteurized camel milk for curdling using recombinant camel chymosin. The physicochemical properties of the resulting soft cheese include specific levels of moisture, protein, fat, and ash. Cultured camel milk yields higher-quality cheese than non-cultured milk. The whey by-product is also rich in nutrients and functional constituents.
The use of recombinant camel chymosin to make white soft cheese from camel milk has several advantages. Firstly, it addresses the issue of bovine chymosin's inability to coagulate camel milk. Secondly, camel milk cheese is of high value, particularly in Middle Eastern countries, and can contribute to food security and sustainability. Additionally, the process can lead to added-value products, such as the whey, which has potential applications in various industries.
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Recombinant chymosin is potentially useful in cheesemaking and may replace animal-derived enzymes
Chymosin is a protease found in rennet, which is used in cheese production to bring about the extensive precipitation and curd formation. It is produced by newborn ruminant animals in the lining of the abomasum to curdle the milk they ingest, allowing better absorption. Historically, chymosin was obtained by extracting it from the stomachs of slaughtered calves. However, due to the imperfections and scarcity of microbial and animal rennets, producers sought replacements.
With the advent of genetic engineering, it became possible to extract rennet-producing genes from animal stomachs and insert them into certain bacteria, fungi, or yeasts to make them produce chymosin during fermentation. This process results in fermentation-produced chymosin (FPC), which is used by cheese producers and does not contain any genetically modified components or ingredients. FPC contains identical chymosin to the animal source but is produced in a more efficient and pure manner, making it the ideal milk-clotting enzyme.
Recombinant chymosin, produced in organisms such as Escherichia coli, Aspergillus niger var. awamori, and Kluyveromyces lactis, has become the primary source of commercial chymosin used in cheese production. By 2008, approximately 80-90% of commercially made cheeses in the US and Britain were made using FPC, demonstrating its widespread adoption in the industry.
The use of recombinant chymosin offers several advantages. It provides a more efficient and consistent source of chymosin compared to traditional animal-derived sources. The purity of FPC is also higher than that of animal rennet, ensuring better control over the cheese-making process. Additionally, recombinant chymosin allows for the production of cheese without the need for animal slaughter, which may be preferable for ethical or religious reasons.
While recombinant chymosin has proven to be a successful alternative to animal-derived enzymes in cheesemaking, there have been some initial challenges. For example, in the production of Cheddar cheese, the use of recombinant chymosin resulted in an excessively bitter taste due to the retention of excessive amounts of proteases. However, with further research and refinement, these issues can potentially be addressed, making recombinant chymosin a viable and widely adopted option for cheesemakers.
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Bovine chymosin is the preferred enzyme for high-quality cheese production
Chymosin, also known as rennin, is a crucial enzyme in cheese production. It is an aspartic endopeptidase that is naturally produced by newborn ruminant animals in the lining of the abomasum to curdle the milk they ingest, allowing for better absorption and longer residence in the bowels. This process is mimicked in cheese production, where chymosin causes the extensive precipitation and curd formation that separates milk into curds and whey.
Bovine chymosin is a preferred enzyme for high-quality cheese production due to its effectiveness in milk clotting and its high clotting-to-proteolytic activity ratio (C/P value). The C/P value is a critical factor in cheese production, as a higher proteolytic activity can lead to poorer flavour and texture in the final product. Bovine chymosin exhibits a very high milk clotting activity with a low proteolytic activity, making it particularly suitable for cheese manufacturing.
The structure of bovine chymosin also contributes to its effectiveness. It has a bilobal structure with a deep, extended cleft, and each lobe possesses similar folds. The principal catalytic residues are Asp 32 and Asp 215, and the bilobular structure is maintained by a network of hydrogen bonds involving specific amino acids. This structural stability is essential for the enzyme's functionality.
Additionally, bovine chymosin has been the focus of extensive research and development. With the advancement of genetic engineering, producers have been able to extract rennet-producing genes from animal stomachs and insert them into bacteria, fungi, or yeasts to create genetically modified microorganisms that produce chymosin during fermentation. This process, known as fermentation-produced chymosin (FPC), isolates chymosin from the fermentation broth, ensuring that the final product does not contain any GM components. FPC has been on the market since 1990 and is widely used by cheese producers due to its efficiency and purity.
Furthermore, bovine chymosin has been successfully expressed in tobacco plants, providing an additional source for cheese production. This approach offers a potential solution to meet market demands and reduce production costs. The expression level of chymosin in tobacco plants varied, but the highest yield reached 83.5 ng/g fresh weight, which is approximately 0.52% of total soluble protein. The plant-derived chymosin retained its milk-clotting activity, demonstrating its potential for use in cheese processing without the need for protein purification.
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Commercial chymosin is produced recombinantly in Escherichia coli, Aspergillus niger, and Kluyveromyces lactis
Chymosin is a protease found in rennet and is used in cheese production to induce curd formation. Commercial chymosin is produced recombinantly in Escherichia coli, Aspergillus niger, and Kluyveromyces lactis.
Escherichia coli, or E. coli, is a type of bacteria that has been genetically modified to produce chymosin during fermentation. The rennet-producing genes are extracted from animal stomachs and inserted into E. coli, which then produces chymosin. The genetically modified E. coli is killed after fermentation, and the chymosin is isolated from the fermentation broth. This process ensures that the final product does not contain any genetically modified components. The purified enzyme was found to be suitable for manufacturing Cheddar cheese, as it did not affect clot times, cheese quality, or cheese acid development.
Aspergillus niger is a type of fungus that has been genetically modified to produce chymosin. Similar to the process with E. coli, the rennet-producing genes are extracted from animal stomachs and inserted into A. niger. This process results in the production of chymosin during fermentation. A. niger is one of the most widely used organisms for producing fermentation-produced chymosin (FPC).
Kluyveromyces lactis is a type of yeast that has been genetically modified to produce chymosin. The donor DNA for chymosin is obtained from calf stomach, and the DNA sequence is then inserted into K. lactis. This genetically modified organism produces chymosin during fermentation and is used in milk processing for cheese production and the production of fermented milk products. K. lactis is another commonly used organism for producing FPC.
The use of these recombinant organisms to produce chymosin offers several advantages over traditional methods of extracting chymosin from animal sources. Recombinant chymosin is produced more efficiently, is considered the ideal milk-clotting enzyme, and has been on the market since 1990. By 2008, approximately 80-90% of commercially made cheeses in the US and Britain were made using FPC, demonstrating the widespread adoption of this method in the cheese industry.
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Recombinant chymosin has been used to produce a variety of cheeses
Chymosin is a protease found in rennet, an aspartic endopeptidase belonging to the MEROPS A1 family. It is used in cheese-making to cause extensive precipitation and curd formation. The native substrate of chymosin is K-casein, which is specifically cleaved at the peptide bond between amino acid residues 105 and 106, resulting in the formation of calcium phosphocaseinate.
Historically, chymosin was obtained from the stomachs of slaughtered calves. However, with advancements in genetic engineering, producers have transitioned to recombinant chymosin, which is produced by inserting rennet-producing genes from animal stomachs into bacteria, fungi, or yeasts. This method allows for the isolation of pure chymosin during fermentation, resulting in a more efficient and cost-effective process.
Recombinant chymosin has been widely adopted by the cheese industry and is used in the production of a variety of cheeses. By 2008, approximately 80-90% of commercially made cheeses in the US and Britain were produced using fermentation-produced chymosin (FPC). FPC is considered the ideal milk-clotting enzyme and has been on the market since 1990. It was the first artificially produced enzyme to be registered and approved by the US Food and Drug Administration (FDA).
FPC is produced using microorganisms such as Escherichia coli, Aspergillus niger var. awamori, and Kluyveromyces lactis. These microorganisms are genetically modified to produce chymosin during fermentation and are then killed after the process, ensuring that the final product does not contain any GM components. The most widely used FPC is produced using the fungus Aspergillus niger or the yeast Kluyveromyces lactis.
The use of recombinant chymosin has been specifically examined for the production of Cheddar and Colby cheese. Initial results for Cheddar cheese manufactured with recombinant chymosin indicated excessive bitterness, which is typical of cheese retaining excessive amounts of proteases. However, no differences were noted in the yields of Colby cheese produced with calf rennet or recombinant chymosin.
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Frequently asked questions
Recombinant chymosin is a type of chymosin that is produced by inserting rennet-producing genes from animal stomachs into bacteria, fungi, or yeasts. This process allows the microorganisms to produce chymosin during fermentation.
Traditional chymosin is obtained by extracting it from the stomachs of slaughtered calves. Recombinant chymosin offers a more efficient and pure alternative to traditional chymosin.
Recombinant chymosin is used in cheese-making as it can completely replace the animal-derived enzyme. It has been shown to produce cheese of comparable quality to those made with traditional calf rennet.
Yes, cheese made with recombinant chymosin does contain casein. The presence of casein is essential for the cheese-making process, as chymosin acts on casein to initiate milk clotting and curd formation.
