Cheese wheel formed from lactic acid bacteria and shrimp paste.

Beyond Rennet: How Fermented Foods Might Revolutionize Cheese Making

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Lena Voss in Science & Nature September 2025 • 5 min read.

"Unlock the secrets of how lactic acid bacteria from fermented foods like shrimp paste could offer a sustainable and ethical alternative to traditional rennet in cheese production."


For centuries, cheese making has relied on rennet, an enzyme traditionally sourced from the stomachs of young mammals. While effective, this reliance raises ethical considerations for vegetarians and those concerned about animal welfare. Furthermore, the availability and cost of animal rennet can fluctuate, creating a need for sustainable and readily available alternatives.

Scientists are now turning to the microbial world, particularly lactic acid bacteria (LAB), to uncover novel sources of milk-clotting enzymes. LAB are already essential in cheese production, contributing to the acidification and flavor development processes. The exciting prospect is to harness LAB's potential to produce enzymes that can effectively clot milk, offering a viable substitute for traditional rennet.

Recent research focuses on isolating and characterizing LAB strains from diverse sources, including fermented foods. These strains are then evaluated for their milk-clotting activity (MCA) and proteolytic activity (PA), crucial factors in determining their suitability for cheese making. This article explores how LAB, especially those found in fermented foods, could revolutionize the dairy industry.

The Science Behind LAB and Milk Clotting: Can Fermented Foods Replace Animal Rennet?

Cheese wheel formed from lactic acid bacteria and shrimp paste.

The search for alternatives to animal rennet has led scientists to explore the enzymatic capabilities of lactic acid bacteria (LAB). These microorganisms, commonly found in fermented foods, possess the ability to produce proteolytic enzymes, which are capable of breaking down proteins. Milk clotting is essentially a process of controlled protein breakdown, where specific enzymes target casein, the main protein in milk, causing it to coagulate and form a solid curd. The effectiveness of LAB in milk clotting depends on several factors, including the specific strain of bacteria, the growth conditions, and the presence of activators.

A recent study published in the African Journal of Biotechnology investigated the potential of Pediococcus acidilactici SH, a LAB strain isolated from shrimp paste (belacan), to produce milk-clotting enzymes. The researchers evaluated the strain's MCA and PA under various conditions, focusing on the impact of different nitrogen sources on enzyme production.

The key findings of the study include:
  • Casein Boosts Enzyme Production: Casein, a milk protein, was found to be the most effective nitrogen source for enhancing MCA in P. acidilactici SH cultures. This suggests that the bacteria are well-adapted to utilizing milk-derived proteins for enzyme production.
  • Optimal Conditions: The highest MCA was achieved at a pH of 6.0 and a temperature of 50°C, indicating the specific environmental requirements for optimal enzyme activity.
  • Enzyme Characterization: SDS-PAGE analysis revealed that the partially purified enzyme had a molecular weight of approximately 29 kDa, providing valuable information for further characterization and potential applications.
These findings suggest that P. acidilactici SH holds promise as a source of milk-clotting enzymes for dairy production. However, further research is needed to optimize enzyme production, purification, and application in cheese making. One crucial aspect is to control the proteolytic activity (PA) of the enzyme, as excessive proteolysis can lead to undesirable flavors and textures in the final cheese product. Achieving the right balance between MCA and PA is essential for producing high-quality cheese with the desired characteristics.

The Future of Cheese Making: Sustainable, Ethical, and Flavorful

The exploration of LAB as a source of milk-clotting enzymes represents a significant step towards a more sustainable and ethical dairy industry. By harnessing the power of microorganisms found in fermented foods, we can reduce our reliance on animal-derived rennet and create new possibilities for cheese making. Further research and development in this area will undoubtedly lead to innovative cheese production techniques, resulting in a wider variety of flavors, textures, and sustainable practices.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

1

What is the primary challenge that scientists are trying to solve by exploring alternatives to traditional rennet?

The primary challenge is to find a sustainable and ethical alternative to traditional rennet. Traditional rennet, sourced from the stomachs of young mammals, raises ethical concerns for vegetarians and those concerned about animal welfare. Additionally, the availability and cost of animal rennet can fluctuate, creating a need for a more reliable source.

2

How do lactic acid bacteria (LAB) from fermented foods, like the one found in shrimp paste, contribute to cheese making?

Lactic acid bacteria (LAB) from fermented foods, such as Pediococcus acidilactici SH from shrimp paste (belacan), are being explored for their milk-clotting enzyme production. These enzymes can effectively clot milk by breaking down casein, the main protein in milk, causing it to coagulate and form a solid curd. This offers a viable substitute for animal-derived rennet, crucial for cheese production.

3

What key factors are crucial when evaluating a LAB strain for its potential in cheese making, and why?

Two crucial factors are milk-clotting activity (MCA) and proteolytic activity (PA). MCA determines how effectively the LAB can clot milk, which is essential for cheese production. PA, the ability to break down proteins, needs to be carefully controlled because excessive proteolysis can lead to undesirable flavors and textures in the final cheese product. Balancing these two activities is key to producing high-quality cheese.

4

What specific conditions and components were found to optimize enzyme production by Pediococcus acidilactici SH, and what are the implications of these findings?

The study found that casein, a milk protein, was the most effective nitrogen source for enhancing MCA in Pediococcus acidilactici SH cultures. The highest MCA was achieved at a pH of 6.0 and a temperature of 50°C. These findings suggest the bacteria is well-adapted to utilizing milk-derived proteins for enzyme production. The results provide valuable information for optimizing enzyme production and understanding the specific environmental requirements for optimal enzyme activity, which is crucial for scaling up and applying this method in cheese production.

5

Beyond ethical considerations, what other advantages does the use of LAB for cheese making offer, and what future developments can be expected?

Besides addressing ethical concerns and offering a sustainable alternative to animal-derived rennet, using LAB offers the potential for new and diverse cheese flavors and textures. Further research and development in this area will lead to innovative cheese production techniques, resulting in a wider variety of cheese. It may also lead to more sustainable practices within the dairy industry. The study of LAB, like Pediococcus acidilactici SH, is an ongoing exploration of enzyme characterization and optimization for cheese production.

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