A familiar technology in an unfamiliar place
Ask most Indian dairy professionals where ultraviolet light is used in a plant and the answer will usually be water treatment. UV systems are familiar in process-water loops, drinking-water lines and effluent-treatment systems. Yet passing milk, whey, cheese brine or a valuable protein stream through ultraviolet light still sounds unusual. That perception is beginning to change.
Ultraviolet-C (UV-C) covers the germicidal part of the ultraviolet spectrum, roughly 200–280 nanometres. Commercial food systems often use wavelengths close to 254 nm. At these wavelengths, microbial DNA and RNA absorb UV energy, causing damage that prevents microorganisms from multiplying. Unlike thermal pasteurisation, UV-C does not depend on heating the entire product and is therefore generally considered a non-thermal, or more precisely low-thermal-load, intervention.
The attraction for dairy is straightforward. Heat is dependable, well-regulated and deeply embedded in plant design, but it can also denature proteins, alter flavour, promote Maillard reactions and reduce the functional value of sensitive fractions. As India moves beyond liquid milk and traditional products towards whey proteins, milk protein concentrates, immunoglobulins, lactoferrin and specialised nutrition ingredients, the cost of heat-related quality losses becomes more significant.
Why milk is far more difficult than water
Water treatment makes UV-C look simple. Clear water allows light to travel through the liquid, enabling a conventional reactor to deliver a relatively predictable dose. Milk is almost the opposite. Fat globules scatter light, while proteins and other solids absorb it. Even skim milk has relatively low UV transmittance, while whole milk and cream are more challenging.
If milk flows through a straight tube around a lamp, liquid close to the lamp may receive greater exposure while material farther away receives less. This creates two risks. Under-dosed zones may allow microorganisms to survive, while excessive exposure can increase the potential for unwanted chemical or sensory changes. Simply installing a larger lamp is therefore not an adequate solution. The central challenge is hydrodynamics: ensuring that the liquid receives a sufficient and reasonably uniform UV-C dose.
Modern dairy UV-C systems use thin films, turbulent flow, vortical movement, coiled paths or combinations of these approaches. Reactor geometry, flow rate, viscosity, optical absorbance, fouling behaviour and the target microorganism must be considered together.
The meaningful parameter is therefore not simply lamp power, but the validated UV dose delivered to the product under defined operating conditions.
Dairy plants should approach UV-C as a process-engineering system rather than an off-the-shelf water-treatment technology. The same system cannot be assumed to work equally well for skim milk, buffalo milk, sweet whey, acid whey, cream and cheese brine. Each matrix requires its own validation envelope.
Why reactor geometry matters: the Dean-vortex approach
One promising approach uses a serpentine helical tube arranged around a UV-C source. As liquid moves through repeated curves and bends, centrifugal forces generate secondary swirling movements known as Dean vortices. These movements transport liquid between the wall and the core, repeatedly exposing different portions of the stream to UV-C.
In practical terms, the design aims to address the central weakness of UV treatment in opaque liquids: uneven exposure. A straight-flow reactor can expose some product to substantially more light than other portions. Dean-flow mixing disrupts this pattern by repeatedly transporting material across the tube.
The engineering proposition is that this can produce more uniform exposure and improve treatment of optically dense liquids while limiting excessive exposure of the fraction closest to the lamp.
The principle has been investigated in peer-reviewed research. A 2022 Journal of Food Engineering study evaluated a serpentine Dean-flow UV-C system for whole milk using computational fluid dynamics and biodosimetry. Related research has also examined microbial and spore inactivation in whole milk and other opaque beverages.
However, reactor geometry alone does not establish commercial performance. The required dose, flow conditions, product composition, microbial target and fouling behaviour must still be validated at the intended operating scale.
The vitamin-D3 question – benefit, concern or both?
One point in the UV-C discussion is frequently misunderstood. The compound relevant to dairy research is vitamin D3, not vitamin D4. UV exposure can convert naturally present 7-dehydrocholesterol into vitamin D3.
The European Union authorised a specified UV-treated pasteurised cow’s milk as a novel food in 2016, recognising the resulting increase in vitamin D3. This demonstrates that UV treatment can potentially deliver a nutritional benefit in addition to microbial control.
But the same effect can become a process-control consideration. A processor seeking only microbial inactivation may not want an unintended change in nutrient composition or additional labelling implications.
The amount of vitamin D3 formed depends on milk composition, fat level, wavelength, dose and reactor conditions. It should therefore not be treated as an automatic or universally desirable outcome.
Better dose uniformity can help control exposure, but it does not mean photochemical changes disappear. Product-specific testing should quantify vitamin D3 before and after treatment. Where enrichment is intended, dose control becomes a feature; where it is not, the operating window must be established accordingly.
Vitamin D3 is also only one part of the quality equation. Riboflavin is photosensitive, while UV exposure can contribute to oxidation reactions and the formation of compounds associated with light-induced flavour changes. Depending on the product and treatment conditions, other nutrients and lipids may also be affected.
Consequently, microbial validation should be accompanied by sensory testing, oxidation markers and relevant nutrient analysis, along with appropriate oxygen and packaging controls.
Where UV-C is already creating value
The strongest global examples of UV-C in dairy are not necessarily bottles of UV-treated drinking milk. They are applications where heat or membranes create clear operational penalties.
At Arla Foods’ Krusaa cheese plant in Denmark, a UV-based system is used to treat salad cheese brine that had previously been microfiltered. The dairy has reported complete brine reuse, lower salt consumption and reduced disposal of salt-rich retentate. In Poland, SM Ryki has also integrated UV-based brine treatment into cheese production, while in Canada, Amalgamated Dairies Limited has announced deployment for Havarti and feta brine. These examples suggest that cheese brine is among the more mature dairy applications because it is repeatedly reused and carries both microbiological and environmental costs when discarded.
Research and early commercial activity are also expanding into whey, whey protein concentrate, colostrum and bioactive dairy ingredients. Studies on donor human milk are not directly transferable to industrial bovine streams, but they provide evidence of the principle: optimised UV-C treatments can achieve substantial microbial reduction while retaining more sensitive proteins and enzymes than conventional heat treatment.
These are encouraging findings, not grounds for blanket extrapolation. Human milk, bovine milk, whey and purified protein streams differ significantly in composition and optical properties. Nevertheless, the evidence strengthens the case for UV-C where commercial value depends on preserving proteins in a more native state.
Lactoferrin: where every percentage point matters
Lactoferrin is a heat-sensitive iron-binding glycoprotein used in infant nutrition, clinical nutrition, supplements and functional foods. Its value depends not only on recovery, but also on purity, native structure, colour and biological functionality. Conventional fractionation involves separation, concentration, purification and drying, with microbial-control steps incorporated throughout. Severe heat exposure can reduce the quality or recoverable value of the final ingredient.
UV-C could serve as an upstream or intermediate bioburden-reduction step in a lactoferrin-bearing milk or whey stream, potentially reducing reliance on damaging heat treatment before chromatography, membrane concentration or drying.
The opportunity should be described in terms of retention rather than automatic yield enhancement. UV-C does not create lactoferrin, and final recovery still depends on the complete downstream process. Its value lies in preventing losses before extraction. If a thermal step partially denatures lactoferrin or promotes aggregation, a validated non-thermal microbial intervention could help preserve bioactivity and improve the proportion of material meeting premium specifications.
For an Indian processor, the right pilot should therefore compare the complete process against the existing heat-treated route. Key measures should include microbial safety, lactoferrin recovery, bioactivity and final product functionality. Only plant-level evidence can establish the true economic value.
Whey and the next phase of Indian dairy
India’s dairy economy has traditionally been built around milk procurement, liquid milk, ghee, paneer, curd and milk powder. The next phase is likely to involve greater fractionation—separating milk and whey into components for infant nutrition, sports nutrition, medical foods and functional formulations.
This changes the processing question from “How do we preserve milk?” to “How do we preserve the most valuable functionality within milk?”
Whey illustrates the opportunity. A cheese or paneer plant may regard whey as a low-value by-product, while an ingredient plant sees lactose, beta-lactoglobulin, alpha-lactalbumin, minerals and potentially other bioactive fractions. Heating provides microbial safety but can denature whey proteins, alter solubility and contribute to fouling during downstream processing.
A controlled UV-C step before concentration or drying could reduce microbial load while limiting thermal damage. This could support better functional protein recovery and potentially reduce the severity of subsequent heat treatment.
The benefit is not simply nutritional. Native proteins can command greater value because of their solubility, gelling, foaming or biological properties. Less denaturation may also improve downstream processing and reduce product losses. Lower thermal loads could further reduce energy consumption and cleaning requirements. These benefits must be demonstrated against each plant’s baseline, but they align closely with India’s need to extract greater value from every litre of milk.
UV-C may also have applications in cheese brine, process water, evaporator condensate, lactose streams, colostrum and selected pre-treatment steps before membrane fractionation. The most practical adoption route is likely to begin with such bounded applications, where processors can measure value without immediately changing the regulatory identity of consumer milk.
What should concern processors
UV-C is promising, but it is not forgiving of poor engineering.
The first concern is uneven dose in opaque liquids. A system must demonstrate that the least-exposed zone receives the required dose. Computational fluid dynamics can help, but microbial challenge testing and biodosimetry remain essential.
The second concern is spores. Vegetative bacteria are generally easier to inactivate than bacterial spores. Depending on the target, UV-C may therefore need to be combined with mild heat, bactofugation, microfiltration or another hurdle rather than used alone.
Third is fouling. Protein and mineral deposits on tubing or lamp sleeves can reduce UV transmission and create shadowed zones. Hygienic design, validated CIP and continuous monitoring are therefore essential.
Fourth is regulation. The regulatory position for UV-treated dairy products varies by application and jurisdiction. Existing approvals for specific products or processes should not be interpreted as universal approval. Indian processors considering commercial deployment should engage FSSAI early and establish whether UV-C is being used as a processing aid, an additional safety hurdle or a replacement for a defined pasteurisation step.
Finally, claims must match evidence. “Non-thermal” does not mean risk-free; a “five-log reduction” is meaningful only when the organism, product, dose and test conditions are specified; and “higher yield” must be demonstrated through a complete mass balance.
Conclusion: A targeted opportunity, not a replacement for heat
UV-C is unlikely to replace thermal processing across India’s dairy industry, and the technology should not be judged on that basis. Its more realistic opportunity lies in targeted applications where conventional microbial-control methods impose a quality, operational or economic penalty.
The experience with cheese brine, together with emerging research on whey, lactoferrin, colostrum and other sensitive dairy ingredients, suggests that UV-C could become increasingly relevant as the industry moves towards higher-value fractionation and functional ingredients.
The challenges remain significant. The optical complexity of dairy streams, dose uniformity, fouling, spore resistance, product-quality changes and regulatory requirements mean that performance cannot be assumed from water-treatment applications or laboratory results.
For Indian dairy processors, therefore, the question is not whether UV-C will replace pasteurisation, but where it can create value alongside existing technologies.
The technology is promising, but its future in dairy will ultimately depend less on the power of the lamp than on the precision of the process.
References are available upon request.