Page 32 - FoodFocusThailand No.155_February 19

STRONG QC & QA

Avoiding Stored Product Spoilage

Many food and beverage manufacturing processes require a product to be stored in a holding tank for a few
hours, days, or weeks. The purpose may be temporary storage before packaging, or longer-term storage where
a reaction, such as fermenting, needs to occur before processing continues.

While storage is an important step in food and beverage manufac- contaminants while preserving the aseptic conditions favorable to
turing, it can be prone to spoilage unless plant managers take pre- aerobic fermentation.
cautions. Without protection, air that harbors bacteria, dust, pollen, The sterile air box does not use a separate compressor or gas
water, oil aerosols, and vapors can enter the tank and spoil or con- cylinder, as in tank blanketing. Instead, a low-pressure blower produces
taminate a product. enough positive pressure to keep unfiltered air out of the tank. Sterile
There are three commonplace methods for avoiding product air boxes are a full air purification solution that come equipped with
spoilage and contamination in holding tanks: Tank blanketing; Sterile blowers, pre-filtration, and a sterile air final filter. They’re available in
air box systems; and Sterile air tank venting. both stationary and mobile models, which make plant modifications
The costs and advantages of these solutions vary widely, so it’s easier.
important to use them in appropriate circumstances. Let’s compare While less costly than most tank blanket systems, sterile air boxes
their relative benefits and costs. are still a considerable investment. Depending on size of the application,
Tank Blanketing - The most familiar solution is tank blanketing, the systems cost upwards of $20,000.
sometimes called “padding” or “buffering.” In this method, an inert gas Sterile Air Tank Vent - For many applications, the most cost-efficient
such as nitrogen is used to fill the empty volume of a tank, covering solution for protecting storage tanks is the sterile air tank vent. Placed
the product with a protective layer. at the top of the tank, this vent allows air to flow in and out, compensating
Tank blanketing is most appropriate in applications where exposure for changes in volume. Inside the housing is a sterile-grade hydrophobic
to oxygen can trigger chemical reactions that spoil products or turn filter element to screen out particulates and bacteria from inflowing air.
them s tale. A gas blanket between the product and tank ceiling Why not just maintain a tightly sealed tank? Because tank pressure
maintains a stable chemical balance. Tank blanketing is often useful fluctuates when products are added or emptied, or when temperatures
with c ombustible foods, protecting the product from oxygen, the change. It’s possible for the tank to bulge or collapse under these
element responsible for both spoilage and combustion reactions. pressures. But if equalizing pressure is your main concern, a gas blanket
This is the most costly solution for storage protection. Producing or sterile air box may be overkill. A sterile air tank vent is a good
nitrogen onsite requires a generation system—or the purchase and alternative in plants where oxidation or fermentation are not concerns.
delivery of bottled nitrogen to your facility. In many cases, nitrogen Sterile air tank vents are especially effective where there is a high
flowing into a holding tank must also be filtered to ensure it’s pure and variability of inflow and outflow sterile air.
dry, adding costs for a filtration system, housings, and elements. The initial purchase of a sterile air tank vent requires only the tank
The total cost for nitrogen blanketing can be tens of thousands of vent housing and a sterile-grade air filter. Costs vary depending on
dollars. While it’s a reliable option, it may not be warranted where requirements, but the investment starts at approximately $1,000. Most
simpler filtration is appropriate. sterile air tank vents are clean-in-place compatible.
Sterile Air Box System - The second most common method for If you’re a fiscally minded manager in food processing, it pays to
protecting food and beverage products in a tank is the sterile air box. know the spoilage risks in your holding tanks and choose storage
This option works well in applications that require clean, bacteria-free protection scaled to those risks. The range of options includes solutions
air in and around their processes. It’s also appropriate for processors that are appropriate for your needs and budget.
of d a iry, sour, brine, or alcoholic products because it filters out

32 FOOD FOCUS THAILAND FEB 2019

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