A research team at DTU conducted a literature review of cheese fermentation and ripening and identifies five underused, evidence-based measures to improve efficiency and sustainability in cheese production.
A large share of milk ends up as cheese, which comes in a vast range of varieties, is satiating, and keeps well. Combined with our culinary heritage, this makes cheese a very popular dairy product, yet it is also resource-intensive to produce. One of the points raised by the researchers is that whey can be exploited far better than is currently the case in many dairies around the world.
“When dairies produce one kilogram of cheese, they simultaneously produce up to nine kilograms of whey. Whey contains most of the milk sugar as well as important minerals and vitamins, yet today it is often sold cheaply to large whey refineries, and on a global scale a significant share is discarded as waste. That is both a loss of a valuable raw material and associated with handling costs for dairies,” says Associate Professor Christian Solem of the DTU National Food Institute.
Within cheese fermentation there is another challenge that could potentially be solved quite simply—namely bacteriophages. Bacteriophages are viruses that can kill the lactic acid bacteria so crucial to cheese production. A phage attack can delay or ruin an entire production run. Dairies therefore typically rely on cumbersome procedures in which they rotate between different cultures.
“Our review shows that, by encapsulating the lactic acid bacteria in the curd before they are added to the cheese vat, the dairies can protect them against bacteriophages,” says Postdoc Shuangqing Zhao of the DTU National Food Institute.
Five under-utilised measures
In the study, the researchers point to five measures that could potentially be implemented with limited process changes in many dairies:
1. Use more autolytic starter cultures
When lactic acid bacteria begin breaking themselves down a little earlier in the process (autolysis), they release enzymes and compounds that can develop flavour more quickly and more consistently. A new culture can speed up cheese maturation, shortening the time in storage.
2. Adjust surface pH to accelerate ripening
For cheeses that mature via microorganisms growing on the surface, dairies can accelerate the ripening process by controlling the pH of the rind. In addition, it can help avoid problems with unwanted growth such as mould or potentially hazardous Listeria bacteria. It is a matter of adjusting brine, washing, and humidity—capabilities most dairies already have.
3. Prevent phage attack by encapsulating lactic acid bacteria
If the lactic acid bacteria are encapsulated, they are physically protected from viral attack (bacteriophages) during the first critical hours of the process. The method is already known from other foods and can be integrated into a dairy’s normal start-up. This leads to fewer failed fermentations and more uniform batches. It also removes the need for the costly, cumbersome practice of switching between different starter cultures to keep phages at bay. The latter works because bacteriophages only infect certain strains in a culture, but they can gradually adapt to other hosts. When you switch cultures, it takes time before the phages adapt and can spoil the fermentation again. Culture-switching requires extensive planning and maintaining multiple cultures in stock.
4. Controlled use of bacteriophages
Very small, controlled amounts of bacteriophages can be used to make the starter culture “switch itself off” at a specific point in the process. When the bacteria are broken down in this way, they release enzymes and other compounds that contribute to flavour, allowing ripening to proceed more quickly. This requires tight process control and clear parameters, but the method is simple and may be especially attractive for cheese types where flavour development typically takes a long time.
5. Add more value to whey
Technologies for capturing whey proteins and returning them to the curd are described in the literature. According to the study, this can increase cheese yield by up to 30% while preserving nutritional value and reducing by-products. Alternatively, whey can be microbially processed to extract more value (e.g., into ingredients) instead of being sold off cheaply.
A shortcut to cheaper starter cultures
Most dairies today buy ready-to-use starter cultures, so-called DVS cultures, because they are easy to handle and deliver stable results, but they are also expensive. An alternative is to propagate one’s own cultures on site and use them directly in production. The benefit is that only a small portion of the original culture is needed as a “starter pack,” after which the rest can be propagated in-house. In this way, the cost of cultures can be up to a hundred times lower, the researchers note. The trade-off is the need for tighter control of both process and hygiene, because the dairies themselves must keep the cultures stable and consistent. For larger dairies—and for smaller ones that can share facilities—this may be an economically attractive solution.
Implementation depends on cheese type and existing equipment, and the researchers note that some measures will require pilot testing and regulatory clarification.
Facts
The scientific article, “Cheese production revisited – Novel and overlooked strategies for improving efficiency and sustainability of cheese manufacturing”, has been in Food Science & Technology.
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Read about the Research Group for Microbial Biotechnology and Biorefining.
