Separation is a key process that allows the production of various dairy products, from infant formulas to cheese to whey protein powders. Most commonly, a centrifugal separator will separate cream and skimmed milk, while separation processes also allow spore removal, whey treatment and anhydrous milk fat production.
Now, the increased focus from consumers on product safety and purity is pushing manufacturers to adopt more stringent and sophisticated separation processes.
FoodBev spoke with Fredrik Johansson, manager of separators at Tetra Pak, about the latest trends affecting separation, including the difference between hot and cold milk separation, energy efficiency and we discussed the company’s newly-developed polynode technology.
What are the key trends affecting separation at the moment?
Food safety and quality throughout the value chain is always a top concern for clients and consumers.
There are also some other trends within the general trend of concern for food safety, take a trend in infant formula as an example. Young infants are sensitive to environments, including spores, so producers need to ensure that any product impurities are removed during processing. At the same time, they must carefully balance the ratio of whey protein – the most important highly nutritious ingredient in the formula – to mimic breast milk and maintain product quality.
Another trend is the healthy lifestyle trend, which is driving demand for whey protein. Consumers typically want the highest protein products they can get with the lowest fat.
This is where a high-quality separator can help producers achieve business growth while optimising their operational performance. Besides skimming off cream from milk or clarifying cheese curds from whey, separation is vital to myriad other processes, such as removing spores and bacteria from whey that should be produced into protein powder, and thus helps to deliver products that meet consumer needs.
While hot milk separation has traditionally been a more popular method, cold milk separation appears to be a growing trend. What are the benefits and challenges associated with both methods?
The choice of whether to perform separation at high or low temperatures is a critical one for dairy operators. Hot milk separation is the more widely used application as it offers improved separation efficiency and higher capacity for production lines, but cold milk separation using high-quality equipment offers several compelling advantages.
Hot milk separation is performed at a temperature of about 50°C, while cold separation is typically at 10°C or lower. Because hot milk is less viscous than cold milk, it can pass faster through the separator, enabling higher production volumes – and is sometimes preferred by dairies for this reason. Separators working on hot milk are typically integrated into a milk pasteuriser enabling cream separation, in-line fat content standardisation and pasteurisation in one processing unit.
On the other hand, cold milk separation has its own benefits. It may, for example, allow longer production run time by avoiding heat-induced fouling at lower temperatures. It allows for longer run times between cleaning in place, which reduces total costs.
Another advantage of cold milk separation, in particular for powder and cheese manufacturers, is that it also reduces the potential growth of thermophilic and thermoduric bacteria, which are capable of surviving high temperatures. This is important for many products — for example, strict rules surround infant formula production.
As the regulations get tighter, the higher microbiological quality argument may work in favour of cold milk separation.
Can you tell us about Tetra Pak’s polynode technology? What are its core advantages and who is it suitable for?
Polynode technology represents a major breakthrough in separation as it eliminates the need for traditional welded spacers and replaces them with micro-embossed polynodes. This has made it possible to reduce space between discs by as much as 35%, thereby substantially increasing the separation surface through allowing more discs in the disc stack. In practice, this means that a separator equipped with polynode discs has a significantly higher capacity than its predecessors.
Capacity is not everything. As an alternative for dairy producers, the use of polynodes enables an increased separation efficiency at a maintained capacity. This is interesting for customers who, for example, want to remove as much fat as possible to achieve their end-product specifications.
The capacity of a separator equipped with polynode discs is 9% higher compared to the previously largest hot-milk separator from Tetra Pak.
As many companies are under pressure to reduce their environmental impact, what types of separators can help businesses achieve this?
Separators are one area that processors can target for emissions reductions. A separator typically accounts for a small but still significant share of the energy consumption in dairy processing.
An energy-efficient separator makes a considerable difference to our customers’ energy consumption. So, choosing the right separator is becoming one way for our more environmentally-minded customers to work towards their sustainability ambition – even small savings grow large over time.
In the longer term, investing in a low-energy separator can generate significant savings not just for the planet but also financially, especially when accompanied by optimisation of other line equipment. Food quality – another sustainability aspect – is also important when choosing a separator. Here, hermetic separators offer advantages compared to other designs as they do not let in air that can, for example, cause foaming.
But it is in energy saving that hermetic separators come into their own. The airtight design of the separator, with the inlet at the bottom and the outlet at the top, cuts energy use by up to 20% compared to other separator designs.
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