Best Practices for Preventing Microbial Contamination During Bottling

Last updated: 6/2021

Applies to: Beverage producers looking to ensure a final package that is microbially stable. Beyond filtration, there are several other considerations that should be taken into account, including several sources of potential bottling day contamination.

Bottling is a Critical Control Point

Bottling is typically the last critical control point before wine leaves the control of the producer. It is especially important at this stage to ensure that spoilage microorganisms are completely excluded from the final product. Two major components of this effort are:

  • Good pre-bottling filtration practices
  • Good bottling day practices to avoid contamination, especially if sterile filtration has already been completed. Read on to learn more about our best recommendations for avoiding contamination on bottling day.

Avoid Large SO2 Additions

Refrain from making large (>20ppm) SO2 additions right before bottling. Such substantial additions can potentially shock and shrink bacteria to a size small enough to pass through the final filter when enough pressure is applied. Instead, adjust your dissolved oxygen to the lowest possible levels (<0.5ppm) to keep the SO2 as efficient as possible and remember to re-check SO2 after sparging.

Sterile Filter Gasses

Chemical and microbial contamination from compressed gases is an under-appreciated risk during bottling. Consider the sterile filtration of all gases used during bottling or sparging.

Properly Clean Bottling Equipment

Bottling lines and associated equipment should be cleaned and sanitized at shut-down and again at start-up if a pre-determined internal cleaning. An external cleaning of the filler should be conducted at start-up, shut down, and at various time in-between (e.g. scheduled breaks, production downtimes).

Use "Clean" Water for Cleaning

Make sure your bottling line is cleaned and sanitized properly and frequently with clean water. The organisms that live in water are generally not beverage-spoilage organisms; However, water is a fantastic solvent and it can contain many other notable impurities.

Some of these impurities can cause scale on equipment, which can be hiding places for biofilms. They can also interfere with the efficacy of your cleaners. One option for water filtration is the SCOTTCART™ AQUA housing and cartridge filter system comprised of a three-stage filter ending with a 0.3μ cartridge to produce a microorganism-reduced, suspended-solid-free water.

Consider Final Package Stabilization

It is important to note that sterile filtration does not lead to package stability due to possible bottling/canning equipment or package contaminations. An increasingly popular method to ensure final package stability is Velcorin® treatment. Velcorin deactivates spoilage microorganisms including yeasts that can cause refermentation, and others that may produce unacceptable sensory attributes. Due to the unique physical properties of Velcorin, a Velcorin doser is required to atomize it into the product at the point of packaging. For more information on using Velcorin, see "Velcorin for Wine Production" or "Velcorin for Cider Production."

Filtration and sterile filtration, while they don't lead to final package stability are still highly recommended for many reasons. One being that Velcorin is less effective if the microbial load is too high.

Don't Neglect The Final Membrane Filter

It's important to use a high quality final membrane filter at bottling and ensure it is used properly. Final membrane filters are generally sterile cartridge filters (0.45 µ) that remove yeast and bacteria that may cause refermentation or other instabilities in bottle. Final membranes should be able to be cleaned, sanitized, integrity tested, and re-used. Be sure to use a high quality filter like ScottCart Membrane PES or ScottCart Membrane PES Pro that can withstand these processes repeatedly without warping or enduring other types of damage that compromise the sterility of the filter. Furthermore, ensure that you are integrity testing your final membrane cartridge both before and after bottling to ensure the membrane functioned properly throughout the bottling run.

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