Page 50 - FoodFocusThailand No.175 October 2020

STRONG QC &
STRONG QC & QAQA

The Importance of

UHT Sterilizer Hygiene

Ultra-high Temperature (UHT) processing in
food and beverage industry to allow for ambient
temperature storage stability has become
ubiquitous in recent years.

To produce ambient temperature shelf stable product the UHT solutions can cause swelling (or gelling) of organic soils that reduces
process needs to achieve “commercial stability”, which defined by the the ability of the caustic solution to solubilise organic load. Conversely,
USDA refers to processes and/or ingredients “to render the product low strength caustic solutions will not have the capacity to solubilise
free of microorganisms capable of growing in the product at non- and stabilise all the organic load present. The need for “wetting” also
refrigerated conditions”. Used as the primary intervention for liquid presents a challenge, especially where crevices or hydrophobic
food products, UHT sterilizers (Defined by the EU as heat treatment surfaces are present in the system. Soil character is another factor
at >135°C in combination with a suitable holding time) form an integral where the soil accumulates over time in a “matrix” structure comprising
part in production of long-life product. The effectiveness of a UHT multiple soil types, typically on a layer of mineral deposit. To effectively
sterilizer (and the whole UHT production process its part of) is measured attack the matrix, different modes of cleaning need to be employed
by the defect or spoilage rate of the finished good produced. concurrently.
During operation, sterilizers accumulate build-up of soil due to To combat these limitations the best cleaning programs are based
burned-on organic components and mineral deposits from the product on more complex or “built” caustic and acid detergents. Typically, the
stream that if left unchecked can lead to increased defect rates, higher caustic detergent will have multiple modes of action that include
operational costs and reduced productivity. Typically, UHT sterilizers chelation, wetting and emulsification agents while the acid detergent
are cleaned with separate caustic and acid steps using detergents will feature an acid blend that promotes both mineral solubility and
containing exclusively caustic soda and nitric acid to remove soil organic soil removal. The effectiveness of such programs is
deposits and restore the unit to a clean state. These are commonly demonstrated in Figure 1, where it can be seen more organic and
referred to as “commodity” based programs. Because they are based mineral soils are removed by the built program when compared to the
on components with single modes of operation commodity programs commodity program on milk soils. The improved cleaning performance
often do not effectively remove all the soil present. Subsequently, the achieved by using complex blends can lead to reduced need to reclean,
UHT will either require additional cleaning before start-up or the reduce sterilizer on-process time and reduced defect rates.
producer will recommence manufacture with a compromised sterilizer.
While the former situation will reduce productivity, the latter could lead
to all three consequences described above.
There are many reasons why standard commodity detergent
programs struggle to remove soil build-up. High strength caustic

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