Bottles and tubs

Closures, tamper evidence and pressure

Updated October 2026

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Neck finish decides what fits Tamper evidence is expected, not premium A live product can pressurize its own container Reseal quality matters more here than elsewhere Match the closure to cold Buy them in the ratio you actually use References

Two things the closure has to do here that it does not have to do elsewhere: show it has not been opened, and survive a product that is still fermenting.

Neck finish decides what fits

Not the diameter by eye and not the look of the thread. Every container page lists the closures verified against its own neck. On this shelf 89-400 dominates, with 45-400, 70-400 and 38-400 behind it, and there are 267 closures matched across them.

Tamper evidence is expected, not premium

Chilled products are bought with the expectation of a seal that breaks visibly, and its absence is noticed in this category more than in any other. A foil seal, a tamper band or a lidding film is close to a requirement of the shelf.

A live product can pressurize its own container

Kefir keeps fermenting under refrigeration and produces gas. A sealed container with a full fill and a rigid closure will build pressure, especially if the cold chain lapses. Either leave headspace, use a closure that can relieve it, or heat treat and give up the live claim.

Reseal quality matters more here than elsewhere

A shelf-stable product is opened once and used. A milk or a yogurt is opened and closed daily for a week, so a closure that seals poorly on the second use shortens the product’s life in the customer’s fridge and gets reported as early spoilage.

Match the closure to cold

Materials behave differently at refrigeration temperature, and a liner that seats well on a warm bench may not seal the same way cold. Verify the seal at the temperature the product actually lives at rather than the one you filled it at.

Buy them in the ratio you actually use

Containers, closures and any separate lidding film are consumed at different rates if any of them are reusable or shared across formats, and ordering each in whatever case quantity it comes in leaves you short of one at the worst moment. Work the ratio from a real production week.

References

21 CFR 1240.61, Mandatory pasteurization for all milk and milk products in final package form intended for direct human consumption, which prohibits delivering such a product into interstate commerce unless it has been pasteurized or is made from pasteurized dairy ingredients. law.cornell.edu

21 CFR 131.200, Yogurt: not less than 3.25 percent milkfat and not less than 8.25 percent milk solids not fat, with “a pH of 4.6 or lower measured on the finished product within 24 hours after filling.” law.cornell.edu

Written from federal regulation and FDA guidance, not from a laboratory. Pasteurization of milk and milk products in final package form for interstate commerce is a federal requirement, and what your state permits inside its own borders is a separate question. Anything here is a starting point for a conversation with your state department of agriculture, not a determination that you comply.