Hydrogen peroxide bottle sterilizer for aseptic PET filling

01

Set the hydrogen peroxide dose per bottle

FDA's 21 CFR 178.1005 defines the sterilant as an aqueous solution of not more than 35% hydrogen peroxide by weight, meeting Food Chemicals Codex and USP specifications, and permits it, alone or with other processes, to give polymeric food-contact surfaces commercial sterility at least equivalent to thermal processing of metal containers under part 113. Polyethylene terephthalate complying with § 177.1630 is on the list of surfaces it may treat. [1]

Dai Nippon Printing's patent application EP 2 772 447 gives working doses for 500 mL bottles. Where only the bottle was sterilized, it states that 50–100 µL of hydrogen peroxide per 500 mL bottle, or a gas concentration of 5–10 mg/L, was needed. With the preform preheated and pre-sterilized, it reports commercially acceptable aseptic filling at 10–50 µL per 500 mL bottle, or 1–5 mg/L of gas. For the preform pre-sterilization it prefers a condensed film of 0.001–0.01 µL/cm² (35 weight % basis). [2]

Editorial calculation: moving from 50–100 µL to 10–50 µL per 500 mL bottle halves the dose at the top of the range and cuts it by 80% at the bottom; at 24,000 bottles per hour, every 10 µL per bottle is 240 mL of peroxide per hour. The line output is an assumed example. [2]

Give the supplier bottle volumes and neck finishes, PET grade and bottle weight, line output, product (low-acid or high-acid), the target log reduction and test organism, the H2O2 grade you will buy, and how residue will be sampled.

02

Activate with hot sterile air and prove the residue

FDA treats a sterilization process as non-compliant if more than 0.5 part per million of hydrogen peroxide can be determined in distilled water packaged under production conditions, with the assay performed immediately after packaging. [1]

EP 2 772 447 inverts the bottle and blows aseptic air through the downward-facing mouth, preferably heated above 70 °C so that it activates the peroxide, with a nozzle discharge temperature of 50–150 °C (75–120 °C preferred). In its example, 500 mL and 2 L bottles received heated aseptic air at 200 L/min for 3 seconds, and distilled water filled into them afterwards held less than 0.5 ppm hydrogen peroxide. [2]

The same document scores rinse time against five criteria: 0–3 seconds rated poor for residue and sterilization, 3–10 seconds acceptable on all counts, and over 10 seconds best for residue and sterilization but poor for bottle shrinkage and cost. Its pass bands are residue of 0.1–0.5 ppm (under 0.1 ppm best), a Bacillus subtilis spore reduction of 6–7 log (over 7 best) and bottle shrinkage of 0.2–1% (under 0.2% best). [2]

Editorial calculation: 200 L/min for 3 seconds is 10 L of air per bottle, equal to 20 volumes of a 500 mL bottle but only 5 volumes of a 2 L bottle, so a sterilizer that handles both sizes needs its rinse validated on the larger one. [2]

03

Choose bottle, preform or two-step sterilization

Dai Nippon Printing describes conventional aseptic PET lines as relying on large bottle sterilizers, long water-rinsing tunnels and multiple H2O2 evaporators. Its two-step system sprays H2O2 mist on the inner and outer surfaces of preforms on one wheel, removes residual peroxide with sterile hot air on a second wheel, heats the preforms to around 100–120 °C, and then sterilizes the blown bottles in a compact bottle sterilizer without water rinsing. [3]

DNP states that the approach reduces installation footprint by approximately 30%, cuts H2O2 use and associated energy by approximately 40%, and reduces the number of H2O2 evaporators from six to three. [3]

EP 2 772 447 preheats PET preforms to 40–80 °C (50–75 °C preferred) while keeping the mouth below 50 °C to avoid deformation; it states that sterilizing performance deteriorates below 40 °C and that bottles shrink after moulding above 80 °C. The preform body is then heated to 90–130 °C for blow moulding. [2]

04

Peroxide evaporator, mist or gas nozzles, preform pre-sterilizer, hot-air rinse and sterile air

05

Peroxide strength, dose, hot-air rinse, log reduction and residue limit for a PET bottle sterilizer

Ask for sterilization efficiency as a log reduction with the test organism, and for residue results against the FDA limit of 0.5 ppm in packaged distilled water. [2] [1]

06

Send the bottle, product and validation data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Bottles: [volumes; neck finish; PET weight; shapes]
Output: [bottles per hour per size]
Product: [beverage; pH; low- or high-acid]
Sterilization: [bottle, preform or both; target log reduction; test organism]
Sterilant: [H2O2 grade and concentration]
Residue: [limit; sampling and assay method]
Site: [power; steam; compressed air; space]

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