Serpentine coiled-tube UV-C system for pasteurization and sterilization of opaque fluids

This technology uses UV-C lamps or LEDs in a coiled transparent tube to force opaque fluids through a curved path for uniform UV exposure, inactivating microbes to pasteurize or sterilize beverages, foods, vaccines and biopharmaceuticals at high flow rates.

Background

In food and beverage manufacturing, sterilization and pasteurization are critical for eliminating pathogens and extending shelf life, particularly in heat-sensitive products such as juices, dairy alternatives, vaccines, and biopharmaceuticals. Traditional thermal methods often degrade flavor, nutritional value, and bioactivity, prompting a shift toward non-thermal decontamination technologies. At the same time, consumer demand for minimally processed, high-quality products with extended shelf stability continues to rise, creating pressure to develop alternatives that can safely process opaque, UV-absorbing, or scattering fluids without compromising throughput.

Many conventional alternatives face significant drawbacks when handling opaque or highly scattering fluids. Thermal pasteurization can introduce unwanted thermal damage and requires substantial energy inputs, while high-pressure processing demands costly equipment and is limited by batch sizes or pressure vessel constraints. Pulsed electric field treatments, although non-thermal, exhibit reduced effectiveness in fluids with high turbidity, leading to uneven microbial inactivation. Similarly, straight-channel UV systems suffer from poor dose uniformity in absorbing media, often necessitating slow flow rates or multiple passes to achieve target inactivation, which compromises productivity and complicates scale-up and dose verification.

Technology

A serpentine path coiled tube UV system features an ultraviolet-transparent coiled conduit wrapped around low-pressure mercury lamps or UV-C LEDs emitting 253.7–280 nm light. Highly opaque, UV-absorbing and scattering fluids are forced through a narrow, curved flow path to ensure uniform exposure and achieve pasteurized equivalent dose (PED) or sterilized equivalent dose (SED). A predictive algorithm models UV fluence distribution within the scattering medium, and dedicated protocols assess microbial UV-C sensitivity. Integrated sensors verify actual dose delivery in real time. Three flow variants (approximately 250, 1,000, and 4,000 L/hr) accommodate a wide range of liquid foods, beverages, vaccines and biopharmaceuticals across both high-acid and low-acid formulations.

This technology distinguishes itself by delivering consistent UV-C exposure to fluids that traditionally resist UV treatment due to absorption and scattering. The serpentine geometry maximizes optical path length without excessive pressure drop, while the fluence-predictive algorithm compensates for variabilities in opacity. Unlike thermal pasteurization, it preserves heat-sensitive nutrients and bioproducts. Compared with high-pressure processing and pulsed electric fields, it offers lower energy requirements and simpler scale-up. Real-time dose verification ensures regulatory compliance and product safety for applications spanning foods to vaccines.

Benefits

  • Effective inactivation of endospores, vegetative cells, and viruses in highly opaque, UV‐absorbing fluids
  • Uniform UV-C exposure via serpentine coiled tube design and predictive fluence algorithm
  • Non-thermal pasteurization/sterilization preserving nutritional, sensory, and functional properties
  • Scalable flow rates (250 L/hr, 1000 L/hr, and 4000 L/hr) for food, beverage, vaccine, and biopharmaceutical applications
  • Integrated dose‐delivery verification ensuring reliable PED/SED treatment and regulatory compliance
  • Energy‐efficient operation compared to conventional heat‐based pasteurization and sterilization
  • Flexible UV source compatibility (low‐pressure mercury lamps or UV-C LEDs) for diverse implementation scenarios

Applications

  • High acid juice pasteurization
  • Low acid beverage sterilization
  • Vaccine fluid sterilization
  • Biopharmaceutical solution sterilization
  • Dairy milk UV pasteurization

Additional info

A UV-transparent coiled conduit wrapped around low-pressure mercury lamps or UV-C LEDs (253.7–280 nm) forces highly opaque, scattering fluids through a narrow serpentine path, ensuring uniform fluence and inactivating endospores, vegetative cells, and viruses via pasteurized or sterilized equivalent doses. A predictive algorithm models UV distribution, while microbial sensitivity assays and integrated sensors verify delivered dose. Three modular models handle 250 L/hr, 1 000 L/hr, and 4 000 L/hr for food, beverage, vaccine, and biopharmaceutical processing.