Rapid Testing of Water Samples in the Bottling Plant

Following on from the ATP article in a recent blog, this section describes the procedure for rapid microbial testing of water samples.

Because water samples contain very few bacteria, an enrichment technique is employed. This involves taking a sample aseptically, and expelling it via a syringe through a special filter.

After waiting for 30 minutes to allow the microorganisms to recover from the stress of filtration, the filter housing is opened and the filter swabbed, using the special swab used in the ATP meter.

The swab is put back into the swab tube and activated using the snap and squeeze action. The swab is placed in the ATP meter and the measurement started. Results are recorded from the display.

Simple Microbiological Testing in the Bottling Plant

A new type of dipslide has recently appeared on the market which is double sided and able to detect 4 different groups of organisms:
1. Nutrient agar on one side to detect total counts.
2. Chromomeric coliform, E. Coli and pseudomonas aeruginosa on the other side.

It is a very versatile slide that can be used to dip into liquid samples or used as a contact plate on solid surfaces. The nutrient agar reacts with enzyme to produce a colour change which is specific to the bacteria type, allowing easy enumeration.

When sampling fluids, the sample is taken by immersing both sides of the paddle into the fluid to be tested. Excess sample should be gently shaken from the paddle before replacing in the container.

Surfaces can be sampled by allowing direct contact between the agar surface and the test material. The paddle is flexible and can be bent at the upper end to allow both surfaces to come into intimate contact.

Bacterial recovery rate is about 50% so that sweeping an area approximately twice that of the paddle will give a more accurate result. Afterwards incubate at 30/35 deg C for 24-48 hours, when full enumeration should be complete.

Apart from an indicator of aerobic bacteria (TVC), as shown in the picture above, the reverse side will give an indication of coliforms and Pseudomonas according to the following colour scheme: blue/purple or blue/green colonies = E.coli; pink/magenta colonies = other coliforms; buff colonies = Pseudomonas.

Recycling Plastics from the Bottling Plant

I previously attended a seminar run by the Food and Drink Association in the South West of the UK, entitled “Make Money, Not Waste”. This gave an up-to-date picture of latest developments in recycling and sustainability in general. My interest and perspectives were naturally focused on bottled water applications.

The main waste issues for bottlers are caps, 19L bottles and chemical drums, particularly the 25L size. Unfortunately all three items are made of different kinds of plastic which sometimes deters recyclers from collecting smaller quantities. If you are fortunate enough to be near a recycling site there may be an opportunity to drop off unwanted drums during the course of a delivery round by your drivers. However, this is not always convenient.

The organisation WRAP (Waste and Recycling Action Programme) currently has a study underway to collect plastics from smaller companies and deliver them to recycling points. This is useful for those companies who find it difficult to persuade recyclers to collect smaller quantities.

ATP Meters

Over the past ten years or so, a great deal of emphasis has been placed on the use of bioluminescence technology in the detection of microorganisms.

The mechanism by which fireflies produce a flash of light was first analyzed and identified by William McElroy in 1947. McElroy found that central to the light emission process was a specific enzyme reaction catalyzing the consumption of adenosine triphosphate (ATP).

In microbes, ATP can only be detected when living cells are present. It has since been established that the amount of light emitted from this reaction is directly proportional to the amount of ATP present. A high reading of relative light units (RLUs) indicates that the sample contains a high number of micro-organisms, provided that the background ATP level is low.

Unlike traditional testing methods, results from a bioluminescent reaction can be obtained quickly. Light is produced within seconds and can be measured with a luminometer (ATP Meter).

The current palm-sized instruments bring together state-of-the-art photodiode technology with simple user-friendly design to produce an affordable hygiene-monitoring system. Used with  ATP swabs, levels of contamination can be determined in just 15 seconds.

Key features of luminometers include, low cost, high sensitivity, compactness, simplicity in use, self- calibration with background check. Readings may be downloaded onto a PC or, as an optional extra, analysis software will provide spreadsheet-compatible data.

Preferred Bottle Wash/Sanitiser for Polycarbonate

New products specially designed for washing polycarbonate bottles are a rarity on the market. However, one new product provides many benefits for the bottler and gives that added confidence that the bottle is clean and germ-free. The product contains a food-safe disinfectant as well as the cleaning power of other products.

Extensive testing and trials have been carried out which show low TVCs, as expected, but also a reduction in the incidence of green bottles returning to the plant. The new product may be used under adverse conditions, for example, if the heater stops working or the throughput of bottles has to be increased because of production demand. If the concentration of the product is cranked up further, it behaves like a disinfectant and will pass the requirements for EN 1276.

The product generates slightly more foam than a regular bottle wash product, but rinsing is very rapid under normal conditions and the foam is controlled, particularly at normal wash temperatures.

The foam tracer makes the wash solution easier to see and provides reassurance that all parts of the bottle are being thoroughly washed. 

Taps for 25L Containers

The ability to reduce the manual handling of chemical drums can only be beneficial from a safety point of view. Pouring dangerous chemicals from a 25L container into a measuring jug is not the safest of procedures, but many plant operators do this.

As with many things, there is a simple solution. The cap/tap assembly illustrated in the photo provides a simple way of avoiding the lifting and pouring of chemicals. The cap replaces the standard cap and by simply punching out the centerpiece of the new cap, the tap can be screwed into the cap unit. In this way the drum can be left on its side, preferably in an elevated position, and chemical dispensed into the measuring jug via the tap.

The cap/tap unit is of robust construction and resistant to chemicals normally found in the bottling plants.

Alcohol as a Disinfectant?

Surface disinfection is important in the cooler servicing room but it is essential not to leave any residual disinfectant on water-contact surfaces. Peroxide spray is excellent in this respect because breakdown products are water and oxygen. However, some brands of peroxide spray can be expensive.

Alternatives tend to leave a residue of disinfectant unless rinsed off thoroughly. This is true of the low-cost cleaner/sanitizer types of spray and those containing a quaternary disinfectant, which should not be used at all if there is a danger of the product being sprayed onto water-contact surfaces.

An alternative to consider is alcohol. This has been used for many years in the medical profession and in dentistry. Alcohol is very volatile and will quickly evaporate from a surface leaving no residue. The germ-kill effect is excellent and there are no problems of oxidising interaction with skin which leaves those white patches seen with peroxide.

From a cost point-of-view, the alcohol may be diluted with water and still maintain good efficacy. Users in the UK need to be registered  with Customs and Excise but this is a simple formality.

Using strong, lint-free dry wipes and alcohol solutions in the cooler servicing room provides an interesting alternative to peroxide and other disinfectants.