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. 

UV Disinfection in the Bottling Plant and Water Coolers

The advantages of UV disinfection are well-known, for example, there are no by-products, the taste and smell of the water remains neutral, UV radiation is non-corrosive and very effective against parasites and protozoa.

The discovery that UV inactivates Cryptosporidium parvum oocysts has given greater emphasis to the role of UV. Its applications extend beyond potable water to municipal waste water, swimming pools, water features, industrial cooling circuits and industrial process water.

However, an important criterion is the method of generation of UV. There are two main types of UV lamp - low pressure and medium pressure. The low pressure lamp disrupts the DNA in the cell and prevents cell reproduction. Unfortunately, the other proteins and enzymes are not destroyed. The proteins and enzymes are capable of repairing the DNA, particularly in the presence of light, so that disinfection is not complete.

Medium pressure lamps, on the other hand, destroy proteins, DNA and enzymes, so that disinfection is complete. The table below gives a summary of the performance of the two types of lamp.

Low pressure lamps have a high efficiency, low power consumption, are easy to apply and ideal for small flows. Medium pressure lamps are compact, powerful, with an efficiency independent of water temperature and with no possibility of photoreactivation of micro-organisms.

An indication of the UV spectral emission curves of the two types of lamp are shown in the diagrams below.

Which Dry Wipes for Cooler Servicing?

Often, regular paper towels are just not good enough for some of the tough jobs in the bottling plant or cooler servicing room. You need high strength, good absorbency, low lint and a large size for usability over larger surface areas.

The characteristics of preferred industrial dry wipes, would be high strength, both wet and dry, with a dense structure and extremely low lint. Absorption capacity should be, on average, 500% of its own weight and the wipe should be able handle water, oil and chemicals.

During servicing of coolers, no paper pieces should be generated, for example, by tears on jagged edges of the internal casing framework, or during cleaning of taps. In this case, strength of the wipe and resistance to tearing, even when wet, is very important. Normal quality paper towels are not good enough for these strict requirements.

How to Measure Bottle-Wash Cleaner Concentrations

Many customers are using conductivity to measure concentrations of bottle wash detergent. This has several advantages over titration methods, for example, the variability in results from different operators can be virtually eliminated with the conductivity technique. This is particularly true if the titration is complicated and involves more than two chemicals. Furthermore, the chemicals have to be replenished periodically and the measurement time is longer. Conductivity meters have improved considerably in design and simplicity of use, so that several types of “pocket” conductivity meters are now available at reasonable prices.

However, there are differences in quality, related to materials of construction and convenience of design. The  most sensitive part of the conductivity meter is the electrode unit. If the meter is going to fail, then this will usually occur with the electrode unit. Some pocket meters have replaceable electrodes and this is a big advantage, otherwise the meter has to be returned to the manufacturer for electrode replacement.

Robustness is another important factor and the meter should be able to survive being dropped on the plant floor. Some meters are self-sampling, in other words, by dipping the meter in the wash tank sampling drawer, a sample is collected in a small cup surrounding the electrode. All these improvements come at a premium, but at the end  of the day the extra investment is worthwhile. To effectively use the conductivity technique, a calibration graph needs to be drawn showing conductivity versus concentration. Your chemical supplier will be able to provide this for you.

Carry-over is another phenomenon easily measured using conductivity. All that is needed is to establish a baseline conductivity reading for “no carry-over”, your supplier will help you to do this.

Cleaning Schedules for the Bottling Plant

It is important to create a cleaning schedule for your bottling plant.  This may be mapped out in a simple chart, shown in the picture below.  A hygiene manual is essential.  This will have detailed cleaning and hygiene programmes for each area of the plant.  These should be easy to follow and readily understood by new operators.  Bottling plant mangers should check regularly that the schedule is being followed.  All too often, the schedule will "drift" into a shortened version.

Apart from possible hygiene problems, a "drift" of cleaning schedule can be confusing to suppliers.  I have read cleaning schedules from customers and subsequently recommended products based on the schedule.  I then have been surprised when the operators said that the products did not work.  On paying a visit to find out why, and observing the operators working, it became clear that the operators were using a different schedule which actually warranted using the product in a completely different way.

The bottled water industry is not unique in this, in a manufacturing company, the plant operators would not follow manufacturing instructions on a computer screen, they preferred to write the instructions on the wall with a felt pen, their reasoning being that computers were notoriously unreliable.

Obviously, if operators come up with new ideas that improve the cleaning schedule, then their ideas should be adopted and the cleaning schedule changed.

It goes without saying that discrepancies between written schedules and actual practice can cause problems during an audit, if the auditor happens to spot it.

Staphylococcus aureus in the Bottling Plant

S. aureus lives up your nose.  You do not need to be ill to carry this opportunist pathogen around.  However, if you have a habit of touching your nose, have a cold, cough or a fit of sneeezing you can contaminate a large area.  If another person's immune system is down, S. aureus can make that person very ill.

If you happen to sneeze in the bottling plant, this could contaminate the water at that critical stage between filling and capping.  It is essential, in preventing this, to have a positive air pressure either around the bottling machine or preferably throughout the bottling plant.

A high percentage of bacteria in the bottling plant are airborne.  They float in through open doors.  One flush of a toilet releases an aerosol of bacteria many of which remain airborne.  Enterococcus faecalis is very common in indoor environments and represents a high percentage of airborne bacteria.

Check your airflow in the plant and make sure the flow is out rather than in.  Ideally, the bottling plant should be sealed off from the rest of the building, although, for practical reasons, this is not always possible.  Another point is that bacterial aerosols can be formed by spraying the floor too vigorously during clean up.  Always use a foaming disinfectant before spraying the floor with water.

Long-Lasting Hygiene Protection for Bottling Plants and Water Coolers

Some time ago, I wrote about antimicrobial coatings in the Food Industry ("Antimicrobial Surfaces in the Food Industry", New Food, 2, 52-56, 2006).  Applications in the bottling plant and for treatment of water coolers are now a cost-effective reality.  Applied by spray, these treatments provide constant protection against bacterial growth on many types of surfaces within the bottling plant, particularly those areas susceptible to mould growth.

In addition, treatment of door handles or plastic curtains will prevent growth and transfer of bacteria from these surfaces.  The spray should be applied onto a clean, dry surface and allowed to dry.  The product will continue to suppress bacterial growth and mould growth for an extended period.  Areas within the bottling plant where the product may be used are on ceilings and in corners where mould growth usually occurs, on the cap chute and in the machine above the filler head.

Consider treatment of taps or buttons on watercoolers and also drip trays and cup holders.  An obvious application is in toilets for treatment of door handles and taps.  A version of the product is available with detergent included, for easy sanitisation of smaller surfaces, such as cooler casings and fountains.

This technology was originally devised for a hospital environment, but application into the food and beverage industries soon followed.  Application in bottling plants and for water coolers is a logical next step.  One word of caution, application of this product does not mean that you can forget all other cleaning and disinfection in the bottling plant or the water cooler clean room.  It should always be considered as a second line of defence to complement other hygiene measures in your due diligence regime.  

Measuring Concentration of Bottle Wash Detergent

Still doing titrations?  Many bottlers have switched to using conductivity meters to measure the concentration of bottle wash product in the tank.  With advances in technology, conductivity meters have become smaller and easier to use.  The price also has  fallen considerably.

Using conductivity meters could not be simpler, just take a sample from the wash tank and dip in the meter.  When the reading stabilises, look up the reading on a calibration chart and this will give you the concentration.

The pocket conductivity meters are temperature compensating, available in basic form for measuring just conductivity, or more sophisticated systems will also measure TDS, temperature and are self-calibrating.  They are waterproof and also float should you accidently drop them into the wash tank.

If you operate a high throughput machine, then conductivity probes may be used in the machine linked to automatic dosing pumps which maintain a fixed concentration of the product throughout the day.  The concentration of the product in the wash tank will reduce over the day caused by drag-out from the bottle movement and it is necessary to compensate for this loss

Detecting Biofilm and Mould in the Bottling Plant and Water Coolers

How do you detect contamination in your bottling plant or water cooler?  There is a wide variety of diagnostic techniques available these days to help.  Identifying the presence of biofilm or mould can be done in the old fashioned way by feel or using the experienced eye, but it is best to rely on additional help from diagnostic tools.

If you want an immediate answer to the possible presence of biofilm or mould, a simple swabbing test will give you an answer in 10 minutes, based on a colour reaction.  If you want a more quantitative measure of contamination then the use of an ATP meter is required.  These are available in pocket meter format.

If you would like to identify specific bacteria then several techniques are available, some based on pre-made plates with identification charts of the bacterial growth.  You will need a small incubator to use these plating techniques, however the savings on external lab costs will soon pay for the outlay.

A wide range of diagnostic kits is available, including Colilert, Pseudalert, dip slides, SIM plates and Petri plates as well as associated equipment.

Descaling and Disinfecting Water Coolers

Water coolers are prone to scale up if the spring or mineral water is heavily mineralised. The procedure for descaling is not standardised and different techniques are used by different clients.  For rapid descaling, the acid is used in concentrated form, although this may cause safety issues in handling.  Simple dispensing devices are available for this task which avoid manual operations.

The most important operation is disinfecting the water cooler.  Biofilm can easily form during the 3 months between services and this must be removed to prevent further build up.  Biofilm is notoriously resistant to several disinfectants including hypochlorites.  The ideal disinfectant for this purpose is hydogen peroxide.  It will penetrate and remove biofilm without leaving any taint.  Decomposition products are simply water and oxygen. Stabilised products are required to maintain an adequate shelf life and the stabilisers must be food grade materials.

Treatment of taps, air filter, waterguard and spigot are easily accomplished using a peroxide spray while the main reservoir and internal pipework are best treated with a solution of peroxide.

New sprays are available for cleaning and disinfecting the body of the cooler, drip tray and cup holder which have a long-lasting anti-microbial effect

Best Products for Washing Polycarbonate Bottles

I am often asked about bottle wash products and the difference between those on the market.  There is a difference between the products offered and it is valuable to know what these differences are.

Many bottle wash products sold in the UK are alkaline.  Alkaline products are particularly good at removing particulate soil.  Ideally the product should also contain a water softening component which enables a good clean to be obtained even in water with high mineral content.  Even better, if the product contains a biodegradable detergent, this will enhance cleaning and help draining.  It is essential, of course, that the detergent is low foaming at normal wash temperatures, i.e., above 60 deg C.  If you do not see any foam in your bottle washer, this important component is not in your bottle wash product.

Remember, most of the soiling is on the outside of the bottle, particularly the base, where soil is picked up from wherever the bottle has been standing.  Too much caustic or, indeed, too much acid is undesirable and it is a mistake to take products which are normally sold into the dairy industry; these are fine for cleaning steel piping, but not polycarbonate bottles.

However, occasionally there are limitations to the use of alkaline products.  If your bottle washer does not possess a heater and you have to carry out a cold wash, you need something in addition to ensure good bacteria kill.  In this case, use an alkaline cleaner which contains a disinfectant component, such as hypochlorite, but be sure to rinse thoroughly afterwards, otherwise you may get taint problems.

Contamination on Footwear in the Bottling Plant

Apart from airborne infiltration, the second most common entry of microorganisms into your bottling plant, or cooler servicing room, is on the soles of boots or shoes.  This is particularly the case when the bottling plant is located on farm land.

Our colleagues in the food industry solve this problem by allowing only rubber boots as footwear and creating a foot-dip area at the entrance to the plant, or to use plastic overshoes which are discarded after use.

We all know that in the bottling plant these facilities often are not available and therefore it is essential to keep the floor as clean as possible during the shift.  Entry into the bottling plant or cooler servicing room should be restricted to essential personnel and preferably the plant should be sealed off to limit access.  Of course, if a bottle jam occurs this has to be rectified quickly, but an awareness of foot contamination needs to be reinforced with anyone allowed access to the plant.

Preferably use a sanitiser or terminal disinfectant that has residual properties so that the bacteria kill will continue throughout the shift.  The best ones are based on mixed disinfecting components using, for example, quaternaries and biguanides.  These will provide a powerful and long-lasting deterrent to foot-borne microorganisms.

Bottling Plant Disinfection Before Start-Up

Overnight, during shutdown, your bottling plant accumulates bacteria and algal spores. They float in through the doors as people leave or become dislodged from roof areas by draughts.  By the morning the washer/filler is contaminated.

Rather than start up with a contaminated washer, it is becoming good practice to disinfect the machine before operations begin.  Ideal for this purpose is treatment with a fine spray of hydrogen peroxide.  There is no need to rinse afterwards and there will be no problems with taint.  It is important to wear a face mask and face shield during this operation, to protect eyes and avoid inhalation of the fine spray.

Hydrogen peroxide at ready-to-use concentration is available or a more concentrated product is available in 25L containers for use with a venturi spray system.

An alternative approach is to use sachets of chlorine dioxide-generating materials.  The sachets are placed in water and the chlorine dioxide gas evolved disinfects the washer/filler and surrounding area.

Yet another option is to use peracetic acid.  This is normally delivered at 5% concentration and requires dilution down to a use concentration of 0.5% of the 5% product (about 250ppm).  In each case, the disinfectant should be allowed to work for a period of 10-15 minutes before start up.

It is good practice to rinse the pipe line from the holding tank to the filler with disinfectant solution before start up (make sure to rinse).

For general disinfection of floors and walls use a mixed quaternary product because this has a residual effect which continues to work overnight.

Hand Sanitising

Hand sanitising is important, not only in the watercooler servicing room, but throughout the bottling plant.  Handling caps in the hopper, handling filled bottles, adjusting filler heads or clearing bottle jams all have the potential for transfer of bacteria.

Hands should be washed before entering the bottling plant or watercooler servicing area, after using the toilet, after coughing or sneezing and after touching any part of of the face or hair.  The location of hand-wash stations should be pointed out to new employees and a demonstration given of the correct method of hand washing and drying.

It should be emphasized that when gloves are worn, the hands within the gloves, as well as the gloves themselves, must be maintained to the same standard of hygiene.  If you go out of the bottling plant area and then back in again, you should wash your hands.  If you are wearing gloves, operators should change into a new pair of gloves on entering the bottling plant again.  This can be inconvenient if you are out for just a couple of minutes, and some operators forget to do this.

It is important to have a good hand sanitiser or hand disinfectant available, preferably the alcohol-based type which dries quickly on the hands without need for a paper towel.  If you come into the plant area with gloves, after being out for a few minutes, you can also treat the gloved hand with sanitiser without need to change into a new pair.

Hygiene Issues with Tap Water and Bottled Water

There have been many comparisons written and preferences aired about tap water and bottled water in various publications and forums.  Tap water and bottled water are very different in many aspects, but in this article I am concentrating on hygiene issues.

Bottled water is regarded as a food and therefore the hygiene requirements are in line with food production.  Certain pathogenic microorganisms are tolerated in tap water, such as Pseudomonas aruginosa, which are not allowed in bottled water.  The parasitic cryptosporidium cannot pass through the filters used in bottling water, but sometimes this microorganism finds its way into tap water because it is resistant to chlorination and the filtration process used is not able to remove it.  Both these microorganisms can be harmful if ingested by individuals with a low immunity level.

Because cryptosporidium is is a fairly large microorganism, filters prevent access to mains-fed water coolers.  However, it is important to have good filtration devices and to have your cooler serviced regularly.

Another issue with mains delivered tap water is the possibility of biofilm build up in the pipe work.  If left undisturbed, the biofilm does little harm, but if there is a pressure surge in the water supply the biofilm may rupture and release a large colony of bacteria, often Pseudomonas aeruginosa.

Most contamination of bottled water arises from airborne bacteria or from using older 19 litre bottles which have stress cracking in the form of microcracks.  It is difficult to clean and disinfect old and damaged bottles and they should be removed during initial inspection.

Airborne bacteria may enter the water at that critical point during and immediately after filling, before the cap goes on.  The time between these operations should be as short as possible and the bottlewasher/filler should be under a positive air pressure, so that airflow is out of the filler rather than into the filler.  Remember that a stream of water draws air towards itself by displacement.

Another difference in requirements between bottled water and tap water is that migration of substances from packaging (bottles) follows food regulations, whereas migration from pipe work in municipal supplies follows other, less strict, regulations.

After a long dry spell, the first rains wash all the accumulated bacteria and algae into the rivers and waste water systems, resulting in a huge increase in the bio loading arriving at the water treatment plant.  This is detected by the water companies and additional disinfectant measures are taken, but more people seem to get sick about this time.

Although I would prefer to drink bottled water from a hygiene viewpoint, it is extremely important to remain diligent in your bottling plant hygiene operations, particularly if you are in a farming environment, you will be surprised what can float through an open door into your bottling plant.

Spray Cleaning in the Bottling Plant

If you have a fairly large floor surface area in your bottling plant or loading area, spray cleaning is often employed.  This speeds up the process and if you have suitable equipment, the spray device will enable you to spray detergent, followed by a water rinse and provide a final spray with a terminal disinfectant, all from a single piece of equipment.

This multi-purpose spray equipment is not as expensive as you may imagine and certainly speeds the wash-down and terminal disinfection tasks.

One of the dangers of spray cleaning is the possible formation of aerosols.  If the pressure is too high, instead of just wetting the surface, an aerosol cloud containing water droplets, detergent and bacteria will be generated within the bottling plant.

The airborne bacteria will cover the total installation and your good work can be undone easily.  So, keep pressures down, or alternatively use a foaming device, which is by nature at a lower pressure.

A good terminal disinfectant for large surface areas is a mixed quaternary.  This has the advantage of possessing a residual effect without acclimatisation and will continue to kill bacteria overnight.

Contamination of Bottled Water

The nightmare for any bottler is when complaints start coming in about a bad taste in the water.  The immediate question of "what can be the cause?" unfortunately has many possible answers.

Initially consider whether anything has changed: a new bottle wash chemical: a change of machine configuration; a new supplier of bottles or caps; a new customer; a new bottle wash operative.  The list is endless.  Of most concern is whether the taint is caused by bacterial contamination, however, if all your checks have been carried out correctly, this is unlikely.

There are always unknowns which are linked to the customer and the fate of the bottled water at the customers' premises, such as storage conditions.  If you are not responsible for servicing the cooler, this is another area of concern.

Polycarbonate is a porous material and small molecules can enter into the water through the bottle walls.  When you consider that coffee has over 1000 flavour components, storage of bottles near to coffee machines is not a good idea.

Polycarbonate is also susceptible to stress cracking and this appears initially in the form of microcracks, often inside the bottle.  These are wonderful havens for bacteria, algal spores and chemicals, none of which can be rinsed out easily.  The problem is that these residues are not normally detectable by your usual quality checks and the offending material will seep out only after a period of time, usually when the bottle is with the customer.

How can you guard against this?  Well, use a bottle wash chemical that does not cause stress cracking and one that contains a detergent ingredient that can penetrate into microcracks and flush out anything lurking in there.  Try not to use chlorinated bottle wash products if you can help it, unless you have a very efficient rinse process.  Discard older bottles that are beginning to form microcracks.

Keep a stock of selected diagnostic test materials, so that if taint arises, you can undertake rapid assay of the possible contamination.  Watch out for bottles that are beginning to look stressed when they come in for washing.  Remember, taint issues usually occur only after the water has left your plant.

Microbiology Testing in the Bottling Plant

These days there are many diagnostic techniques available to bottlers and watercooler companies who want to take the do-it-yourself approach.  These techniques can shorten the time to obtain a result such as TVC and save you money.

Which technique you choose depends on the degree of accuracy required.  Dip slides have been around for a long time.  These are a low-cost and convenient option for assessing bacterial contamination.  A slide is dipped into the water sample, returned to the transparent container and incubated for 24-48 hours at 37 degrees C.  After this time, the colony count is compared with a series of photos which indicate the degree of contamination.

New developments in dip slides enable you to determine different bacteria types on each side of the dip slide, for example, TVC on one side and Ps. aeruginosa on the other.  The dip slides also are hinged at the top, which allows surface sampling.

An alternative system called Petrifilm (TM) enables you to obtain an accurate count of CFU per cm2 from a measured volume of water.  A 1ml sample of water is taken with a disposable pipette and added to the centre of the film.  The film is then covered and stored in an incubator at 37 degrees C for 48 hours.  Counting CFUs is made easy by a red indicator dye which colours the CFUs and a built-in grid which enables the CFUs per cm2 to be determined easily.

If you want an immediate indication of contamination, then you require an ATP meter.  Dip a swab in the water or swab a surface to be assessed and place the swab in the meter. An immediate numerical reading results.  Now, this is not the actual TVC, but an indication that contamination is present.  The higher the reading, the greater the contamination.

Hand Hygiene and Glove Failure

I read some disturbing information about hand washing recently.  From various surveys among the general public in the UK, it transpires that 31% of men and 17% of women did not wash their hands after using the toilet.  58% of those that did wash their hands used water without soap.  26% of men and 17% of women do not wash their hands before preparing food.

Wearing gloves can lead to a false sense of security.  A further survey showed that with vinyl gloves, 34% allowed bacteria to penetrate and 53% failed in use.  With latex gloves, 20% allowed bacteria to penetrate and 3% failed in use.

This highlights the importance of hygiene training for new recruits in the bottling plant. Make sure that hand washing facilities are well placed and in good working order, with provision of soap and means to dry the hands.

Bactericidal hand soap is recommended for washing followed by alcoholic gel for hand disinfection.  These should be dispensed from hands-free dispensers.  A thorough hand-washing regime is essential whether or not gloves are used.  New glove materials are available which combine the flexibility of latex with the strength of nitrile.

To avoid any transfer of bacteria from touched surfaces, long-lasting disinfectant sprays are available which may be applied to door handles, plastic curtains and surfaces in toilet areas.

Washing Polycarbonate Bottles

I am sure that you are all aware of the factors involved in providing a clean bottle.  These are chemical type, concentration, temperature, physical agitation and time.  However, there is another factor of importance and that is compatibility of bottles with your washing process.

Apart from excessively high temperatures, the factor most likely to affect bottle compatibility is the type of chemical used.  The formulation must be balanced to give good cleaning and appearance with no streaking and maximum bottle life.  Unless the chemical has been specifically formulated for polycarbonate washing, it is likely that problems will arise eventually.

High alkalinity can be the worst offender, but careful formulating will offset the effects of causticity and produce an excellent clean without causing bottle damage.  One of the key ingredients in doing this is the detergent.  By "detergent" I mean a real detergent, not just a mixture of alkali and water softener which is characteristic of many products on the market.  By careful selection of detergent, the bottle will receive protection from the effects of the alkali and, as a bonus, will aid draining and reduce carry over.  If your product does not generate a measured level of foam, it does not contain a detergent.

If your supplier has formulated correctly, he will have carried out compatibility checks on polycarbonate.  The testing involves putting polycarbonate strips under stress by bending and then immersing them in neat product.  The kind of results we obtain are shown in the photo.  This product was highly alkaline with no protection.

You may say that bottle lifetime is not a real concern.  However, there is another, more insidious, factor and that is the formation of microcracks.  These may not be so obvious, but they are breeding ground for bacteria, algae and other undesirables and these bacteria will only emerge after the bottle has been filled for some time, unfortunately when the bottle is with the customer.  Bottle compatibility is therefore important in providing the highest quality product.

Chlorine Dioxide Disinfection and Water Treatment in the Bottling Plant

Chlorine dioxide has been used for treatment of drinking water for many years. Application in the bottling plant for treatment of the water is fairly common and use as a disinfectant for water-contact surfaces is increasing.

Ozone has been used classically for terminal disinfection in the bottle washing process or as treatment of the final rinse water.  Treatment of the water itself is also common despite several disadvantages. These are predominantly the high cost and tendency to create damaging bromates and ketones. 

Chlorinated disinfectants have been used for treatment of water, but in the bottled water industry this is avoided, to prevent formation of halomethanes and haloacids, both of which can produce a taint in bottled water. 

Chlorine dioxide is quite different and does not have the disadvantages of other chlorine-containing compounds. Chlorine dioxide is a gas which dissolves easily in water. The breakdown products are chlorides  which are used by the body in several natural metabolic processes.

Chlorine dioxide is excellent in removing biofilm and is often used in the health care sector for this reason. Application in the brewing industry has been known for many years. What are the applications in the bottling plant?

There are different ways of generating chlorine dioxide.  For automatic and continuous use, the gas is generated by a chemical reaction between two materials which are automatically monitored and mixed. On a cost basis the initial outlay and running costs are much less than using an ozone installation.

                                Chlorine Dioxide Generator for Bottling Plants

For treatment of pipe work and other water-contact surfaces, it is possible to generate the chlorine dioxide manually by mixing a chlorate with a suitable acid and using the mixture immediately. However, stabilised forms of chlorine dioxide are available which remain stable for extended periods if stored correctly.  Several stabilisation systems are used, many relying on careful control of pH.

Chlorine dioxide sources in tablet form are also available, useful for disinfecting water coolers.

Airborne Bacteria in the Bottling Plant

I have written previously about the dangers of airborne bacteria and their role in causing many cases of bottled water contamination.

During production, with efficient positive pressure airflow, this should not be a problem. However, during the night and at the weekend, bacteria, dust, pollen particles and mould spores will settle on your washer, filler, cap chute and other objects in the plant. Start up can therefore be a vulnerable time for your operation.

An effective solution uses UV-C technology to destroy airborne micro-organisms. Untreated air is drawn through a particle filter, removing dust and pollen particles. The air then passes over a 36W compact UV-C tube positioned within a baffle chamber.

This chamber prevents any UV-C light escaping the unit, whilst ensuring all the air drawn in passes over the tube. Treated air is then expelled out of the unit.

The unit has been independently tested to prove its effectiveness against the most common airborne bacteria, yeasts and moulds.

More recently, high tech devices have appeared on the market using cold plasma technology which effectively destroys micro-organisms in the air by generating transient oxidising chemicals.

Hygienic Design of Bottling Plants

One of the observations I have made in visiting many bottling plants, is the wide variations in machine configuration and location. The design of the plant environment is important in maintaining good quality water and avoiding contamination problems, in particular around the bottle washer and filler.

It is important to keep the bottle washer, and particularly the filler, enclosed and protected from the outside environment as much as possible. One enigma in all this is that you are introducing dirty bottles into an area that you want to keep clean. This is where configuration of the machine is important.

The incoming dirty bottles should be kept away from the filler. Some configurations are not ideal particularly where the conveyor carrying dirty bottles passes close to the filler. The bottles are often covered in dust and I have seen operators occasionally wiping dirty bottles with a cloth before loading the washer. This causes dust to fly around. 

The fork-lift truck and conveyor loading area is often separated from the washer by plastic curtains, which is not best practice. The washer and filler should never be in an open area with open access to other areas such as warehousing.

If plastic curtaining is used, it must be kept clean otherwise bacteria can build up rapidly. Positive air pressure should be maintained in the bottling plant room, or if that is not possible, within the machine itself. 

Access to the bottling plant should be restricted to essential personnel. Preferably white boots, coats, hats and protective gloves should be worn in the plant. The latter should be changed regularly or disinfected with an alcohol gel.

Bottle Washing in Cold Water?

In talking with bottling plant supervisors, one of the concerns has been how to safeguard against plant malfunctions.

For example, if the heater is on the blink and you cannot reach the desired temperature of 62-63 deg C, what do you do - stop production, battle on at a lower temperature and keep your fingers crossed? What do you do if the ozonator starts to play up - stop production immediately?

Plant operators have been asking for some kind of safety net or second line of defence when these things happen. In fact, there are bottle wash products available that will help address these issues.

If the bottle wash product contains an additional disinfectant component, the value of this will come into play when things start to go wrong.

The disinfectant component has to be approved for indirect food contact and not interfere with the cleaning performance. In the event of an equipment malfunction, the concentration of the product may be increased to  give an additional sanitising safeguard.

It could be ideal for those who have no alternative but to wash in cold water. The degree of additional sanitising may be adjusted simply by increasing the overall concentration as required.

Sanitising Wipes and Sprays for Cooler Servicing

A lot depends on how you want to use wipes and some users prefer a cleaning/disinfecting wipe rather than a purely disinfecting wipe.

If the wipe is to be used for sanitising watercoolers, there can be problems in effectively treating tap areas simply because it is difficult to get into the tap. Sprays, on the other hand, are much better for this purpose.

The wipes are great for cleaning and disinfecting the outer casing of the cooler. However, a number of sanitising wipes on the market contain a quaternary ammonium compound as active ingredient and these wipes should not be used on surfaces that subsequently come into contact with the drinking water.  The reason for this is that bio-acclimatisation can occur because of the slight residual effect of these compounds.  This could lead to biofilm growth.

At the end of the day, I would recommend sprays rather than wipes, but if you prefer to use wipes, then make sure that the wipes have a high wet strength and low lint content, otherwise contamination with wipe fragments could occur in the cooler.

Ensure that the wipe does not dry out in the packaging, alcohol-based wipes are notorious for this.  Pouches with a resealable flap are best for preventing dry-out.

Some sprays are based on peroxide, although a new generation of sprays is available which uses a long-lasting disinfectant effect.  The latter is available as a sanitiser (cleaner/disinfectant) as well as a terminal disinfectant. 

How to Disinfect Water Coolers

A useful product available on the market is a disinfectant based on hydrogen peroxide and silver ions. It is recommended for servicing coolers and general disinfection around the bottling plant.

The packaging provides a combination rinse and spray, enabling application by dilution for watercooler disinfection and as a simple spray, by means of the integral and refillable trigger bottle provided. These have proved to be extremely popular, particularly since the price is much less than other alternatives on the market.

It is appropriate to explain the action of silver ions in the formulation. Silver is a well-known biocidal material,  in fact the Romans were aware of this action and stored wine in silver containers to prevent biological deterioration. 

The combination of silver and hydrogen peroxide creates a synergistic disinfectant effect that is more powerful than hydrogen peroxide alone. This, in theory, enables you to use less of the product than hydrogen peroxide alone. 

Among the advantages for the combination are: the more rapid kill rate; the greater effectiveness on algae and fungi; a longer-lasting biocidal action; greater stability in the presence of heat and light and an expected higher efficacy on biofilm.

An additional plus point for the product is the flexible combination pack which enables the trigger spray to be  refilled from the 5 litre container using the convenient tap.

Treating Green Bottles

Green bottles have always been something of a vexed question. Once the filled bottle leaves your plant, you have little control over what happens to it, particularly when it is empty and left for collection.

Bottles left in sunlight and a warm environment are susceptible to algal growth. When green bottles are returned for filling what do you do? On the one hand you can throw them away, but if the algal growth is not too bad perhaps they can be cleaned and returned to the wash/fill cycle.

Green bottles should never be put through the normal washing process, otherwise the bottlewasher quickly becomes contaminated with algae. A separate process is required using good mechanical action, preferably with brushes, and a strong bleaching detergent. Good rinsing is essential.

Simple rigs can be set up to carry out this task and the best detergent to use is a low foam chlorinated alkali at a temperature of about 55 deg C. The temperature must not exceed 60 deg C otherwise the chlorinated product will degrade and cause corrosion, even of stainless steel.

Bottle Washing in Hard Water

Many bottlers wash their bottles in the same spring water that goes into the bottles. I assume that the cost exercise has been done that shows it is more cost effective to do this rather than use mains water.

Using spring water can be a problem if the water contains a lot of calcium, magnesium and some iron. The detergents used in bottle washing have to be specially formulated to take account of the high hardness sometimes encountered and higher concentrations of product are often necessary.

 A saving on detergent can be made if a water softener is used, although the running costs of resin replacement need to be taken into account.

If your water is very hard, it is essential to ensure that the dosage of detergent is adequate and that compensations are made for drag-out during the course of the day. The bottles will “drag out” detergent product as they move into the rinse section. Some washers do not have the luxury of a drain time before passing into the rinse.

The consequences of under-dosing can be catastrophic in very hard water resulting in rapid scale-up of tanks and heaters. It is essential therefore to monitor detergent concentration regularly which may be done easily with a conductivity meter. A more sophisticated system involves automatic top-up using a conductivity probe linked into the dosing device.

                                         Scaled-up heater element

                                           

Reusing Old Water Coolers

The Waste Electrical and Electronic Equipment Directive has been in force for some time. This is intended to ensure that all electrical appliances such as watercoolers and TV monitors are dismantled and recycled at the  end of their useful life, rather than dumped into landfills.

The cost to the watercooler industry is estimated at between £8 million and £10 million. Invoices should show a recycling charge for all coolers bought or rented. This will help monitor compliance and be checked in distributors’ audits.

However, I am sure that we will see refurbishment and reuse of old product rather than just disposal. Innovative solutions will be created for using component parts of old coolers. Whereas the old material may not be reused for water contact in coolers (due to food-contact materials laws) the manufacturer may trade its recycled materials, similar to the trade in waste polycarbonate.

This initiative is to be applauded, but it raises questions of maintaining good hygiene in refurbished coolers. Surfaces which become worn or develop microcracks are more susceptible to growth of biofilm and  more difficult to clean and disinfect. It is essential, therefore, to have a very efficient cleaning and disinfecting regime.

UV or ozonation may not be completely effective in keeping refurbished coolers free of bacteria. It is important to rely on manual operations- for cleaning, descaling, using appropriate acids, and disinfecting with the best material for dealing with biofilm.

Peroxide, or peroxide synergised with silver, is excellent for destroying biofilm. Descaling is done most cost effectively with high-strength phosphoric acid. 

Because the high-strength materials are difficult to handle, I recommend the use of a dosing device which enables dilution and dispensing into the cooler tank without manual mixing or pouring.  

The issue of refurbishment is still under debate but I expect refurbishment schemes will be developed.

Hand Washing in the Bottling Plant

I cannot emphasize enough the importance of correct hand washing. The hand washing area should have a supply of anti-bacterial soap in a clean, hygienic dispenser. Soap should be non-perfumed, low-odour, mild to the skin and taint free.

The temperature and flow of water can have an effect on the success of hand washing. Water should have a decent flow and temperatures between 40-45 deg C. Taps should be knee operated or a hands-free design to avoid contact with taps and sinks.

Drying hands after washing is important because wet hands reduce the effectiveness of the alcohol disinfectant. The preferred method of drying is with good quality paper towels.

The correct method of washing hands is as follows: wet hands before applying liquid soap, rub hands together vigorously for about 10-15 seconds covering both sides of hands, fingers, thumbs, nails and wrists, rinse thoroughly with clean water and dry with a paper towel, apply alcoholic gel to hands and massage all surfaces, allow to air dry.

If gloves are worn, apply alcoholic gel to glove surfaces before work. Wedding rings can be a site for bacterial pockets and rings should always be lifted and turned when washing/disinfecting.

Insects in the Bottling Plant

Bottling plants should be insect free. The most efficient way of doing this is to install an electrocutor. However, careful thought should be given to the design of the equipment and the siting of the device.

When an insect flies into the electrocuter it literally causes the insect to explode. Unfortunately this creates a lot of debris which can easily fly out into the bottling plant. Look out for designs that minimise excessive spatter-back when the insect is killed.

The unit should not be in the vicinity of the filling section otherwise debris may cause contamination during filling. The design of electrocutors has not changed very much over the years but non-electric systems are available. These use glueboard technology and UV lamps. The insect literally sticks to the glueboard without exploding. 

Another aspect is the lifetime of the UV lamps. The power of the UV light is not constant during use and will tail off after several months becoming less effective. This is not noticeable to the human eye. Ensure that the elements are changed at the correct time and service from the supplier is undertaken regularly.

Flavoured Spring Water?

Consumers are being misled by the term “spring water” and further misled by the flavoured spring water drinks, according to a report in “The Food Magazine”. A survey by the Food Commission found that many such drinks use preservatives, colouring, artificial sweeteners and other additives, even though the name on the front implies a relatively pure drink.

Shoppers complained that what they thought was pure water with a drop of fruit flavouring was in fact a sweet soft drink with preservatives and additives, according to the report’s author. The descriptions on the front of the bottles are very misleading.

Tesco’s Spring Water Drink with a hint of grape and blackberry juice for example, or Boot’s Mandarin Still Spring Water with the flavour of mandarin both contain artificial sweeteners, preservatives and acidifiers. Sainsbury’s Crystal Spa made with spring water and natural tangerine flavour has more added sugar than Coca Cola, while Ribena’s Spring has an incredible 13 sugar lumps in a single serving.

Unlike mineral water, which is tightly defined by law, spring water is less rigorously defined and if a flavouring   agent is added then the product is defined as a soft drink, not bottled water, and all the colouring ingredients, preservatives and sweetening agents used in soft drinks can be added.

When Perrier added “a twist of lemon” to their water they started a trend which other companies have been quick to exploit. Shoppers are paying a lot per glassful - these are soft drinks charged at Perrier prices.

Of course, the Australians have gone one stage further and are selling a sparkling “Alcoholic Spring Water” with flavourings and vodka.

"Bisphenol-A Free"?

There has been much debate in the past about the potential dangers of bisphenol-A leaching from polycarbonate bottles.  A lot of research has been done and the European Food Standards Authority has indicated that there is no evidence of any danger from the use of polycarbonate bottles in the bottled water industry.

However, some countries have advised against the use of polycarbonate bottles in baby feeders where high sterilisation temperatures are often used.  As the debate and research go on, new bottles have appeared on the market in 19L, 11L and other smaller refillable bottles with the statement "bisphenol-A free".

To my knowledge, polycarbonate cannot be made without the use of bisphenol-A, so the new bottles are not made from polycarbonate but rather PET with special additives.  The additives are designed, among other things, to improve high temperature stability while maintaining the clarity of the bottle.  This enables high-temperature washing without shrinkage.

However, the chemistry of the additives is fairly complex and more long-term work would be needed to ensure that recyclability is not compromised when re-worked with standard PET or that leaching of undesirable components is no longer an issue.  I am sure that much work has been done already, but it may take some more years' of research before we can dispel completely all fears about unwanted chemicals entering the food chain.

Foam Cleaning

Foam cleaning can be an ideal way of ensuring good hygiene in the bottling plant. The advantages of foam are numerous: increased contact time maximises active ingredients’ effectiveness; the foam is a visual marker for the operator; the expanded foam reduces water and chemical usage; cleaning of large or awkward surfaces is made easier and quicker and therefore downtime for cleaning may be reduced.

Two pieces of equipment are described here which seem ideally suited to the bottling  plant environment. Neither of them requires compressed air and one of them does not need a water line. 

The first is a pump-up foam unit. The dual tube technology draws the chemical and compressed air from the tank into separate tubes creating thick foam when mixed at the trigger foam wand. Flow in the air tube is controlled by a needle valve giving the user the ability to control the consistency of the foam.

The second unit is a spray and foam dispenser which is wall mounted. This enables the operator to generate a cleaning foam, followed by a water rinse and finally a terminal disinfection, all from one piece of equipment.  The only requirement is a water line.

 A single control knob determines water flow and chemical selection, giving accurate dilutions. A built in foam wand hanger prevents foam wand loss or damage.

The ideal foaming chemical is a chlorinated foamer useful for general disinfection and removing mould growth.  An acidic foaming product is ideal for descaling or brightening stainless steel. Recommended disinfectants for spray application are peracetic acid (for water contact surfaces) and quaternary ammonium solutions for floors and walls.

COSHH and Risk Assessments

The COSHH Regulations are designed to prevent people at work being exposed to hazardous substances. The Risk Assessment is a key part of this. The whole process is usually covered by 5 stages: identification; assessment; prevention/control; training and monitoring.

All chemicals must be itemised which are used on the premises along with a list of current work activities. Labels should be checked on containers to determine type of chemical, method of use and precautions. If the  assessment sheet shows there is no likelihood of risk to health from the substance concerned, no further action is required.

A decision is required for each substance and every time the use of the substance, the method of work, its frequency of use, etc is changed, there will be need for a new assessment.

Identification and assessment of the risk will give you an insight into the control and prevention measures necessary to comply with the COSHH Regulations.

The requirement for risk assessments applies not only for chemicals used in the bottling plant, but also for chemicals taken into customers' premises during water cooler servicing.

Home Cooler Hygiene

Increasing use of coolers in the home and sale of coolers without a service agreement are creating a market for do-it-yourself cleaning and hygiene.

New products are appearing on the market aimed at satisfying this need and already in the USA the opportunities are great, with ever increasing numbers of home coolers. There is, however, a need to educate the user about the necessity for cooler hygiene.

Often a cooler left to its own devices will rapidly accumulate bacteria, resulting in bad tastes and odours and  the danger of making someone ill. Many models enable self-sanitisation by various means, such as UV irradiation and generation of ozone, but many do not have this facility.

There is need for a simple kit that will serve the purpose without difficult procedures or use of dangerous chemicals. A simple system could comprise a disinfectant spray for tap treatment and a small bottle of disinfectant for addition to the reservoir. Food-handling gloves would be useful and a single-use wipe for the exterior.  A set of user instructions would complete the pack. 

The only item missing is a descaler, although there could be a problem with including incompatible chemicals in the same box. However, using a citric acid powder should be safe enough. 

This is an interesting development and one that will create a new type of market. Issues still under debate are pricing and marketing. 

Descaling Water Coolers

I am often asked about descaling watercoolers and recommending the best chemical to use. To a certain extent this depends on the amount and type of scaling but, in general, three types of chemical are used. These  are: citric acid, sulfamic acid and phosphoric acid. 


The strengths of the acids, on a weight for weight basis, increase in the order given and, as a consequence, so does the danger of handling. The speed of descaling increases as the strength increases. On the contrary, the costs of the acids decrease in the ratio 17:14:1.


 So, if you have hundreds of coolers to descale, I would go for the phosphoric acid. However, there remains the question of safe handling.

The dosing device in the picture enables you to mix water and the acid in the correct proportions without having to handle the concentrated acid. The petrol-pump like configuration means that you can treat several coolers in rapid succession.

No electric supply is necessary, just a water line. This enables you to use a strong acid with maximum operator safety.

Detecting Residual Peracetic Acid

After using peracetic acid (PAA) as a terminal disinfectant in the bottling plant or elsewhere, it is important to ensure that no traces of peracetic acid remain on surfaces which will contact food or water.

The easiest way to do this is by using test strips which show different degrees of colour at each concentration level.  However, the lowest measurable level detected by most PAA-specific strips is 5mg/l (ppm).  So, there is no information about residual PAA in the range 0-5ppm.

There is a way around this if you consider the composition of peracetic acid.  It is not a single substance, but a mixture of hydrogen peroxide, peracetic acid and acetic acid in equilibrium.  The equilibrium can shift under the influence of temperature, rate of degradation and water content, plus other factors.

                                                PAA Composition (1)

The peroxide concentration (by volume) is approximately 3.5 times that of acetic acid and approximately 6 times that of the peracetic acid initially formed.  Therefore, a peroxide type residual test strip may be used to safely estimate residual peracetic levels because they will always be lower than that of the peroxide.

Peroxide test strips are available in the range 0.0 - 0.2 - 2.0 - 5.0 ppm.

(1) Vern Taaffe - Reprocessing Products Corp - January 5, 2004

      

Preventing Flying Insects in the Bottling Plant

I have written about electric fly killers previously, where I described the importance of not locating the unit near to the filling head in order to avoid insect debris ending up in the water.


Electric fly killers are often forgotten once installed and reliance is totally on the company servicing the unit. However, it is important to realise that not all UV tubes maintain adequate performance throughout the year and their efficiency cannot be guaranteed to be at optimum levels all year round.

To maintain a satisfactory level of protection, bulbs may need to be changed more than once a year, particularly where species’ populations peak in the late season, also, traps may be under-specified or poorly sited, for example, a lot of ambient UV reduces effectiveness considerably.


The risk of contamination by flying insects can continue into autumn, and beyond, and protection in the bottling plant or cooler servicing room is critical. So, apart from correct location (at least 2m high and away from windows) it is necessary to check the effectiveness of the electric unit periodically.


Fortunately, there is an easy-to-use monitor that can provide a rapid indication of the condition of UV tubes in any electric fly trap. The UVA meter, indicated in the photo, measures tube condition quickly with no calculations necessary. This enables plant supervisors, or indeed, auditors, to record output using a simple 1- 10 scale. There is a moving bar of LED lights which also changes colour according to the condition of the tube. The unit is permanently calibrated and the batteries are user-replaceable with a typical battery life of two years.

Ideally, the bottling plant should be sealed off from the surroundings with close fitting doors and small hatches on conveyors. A door of transparent plastic strips is not always effective and the light from the electric fly killer can actually attract insects into the bottling plant if it is not well sealed.

As a final point, it is interesting to note that an ozone atmosphere generated around the filler is a natural deterrent for insects. This atmosphere will also kill bacteria, although long exposure is harmful to humans.

www.foodhygienetech.com

Removing Labels from 19L Bottles

I have written about label removal previously and described two possible methods of removing residual glue from polycarbonate bottles. These involved either steam removal or solvent removal. 


The surest way is to use a steam gun. The temperature is then high enough to soften the glue and some elements in the glue which are water soluble at high temperatures will be dissolved, although it still will be necessary to use some mechanical action.

Using solvents can be hit-or-miss because there are several types of glue used and although some solvents will work on a wide range of glues there are always exceptions. There is a limitation on the type of solvent that you may use; very strong solvents can get into the polycarbonate polymer and lead to taint problems. 

The type of solvent most often recommended is denatured alcohol. Be careful, however, on the choice of product because some denaturants have a very strong taste, such as Bitrex, which is designed to make the taste of the alcohol unpleasant. Also, the higher the alcohol content, the more expensive the product becomes.

Measuring Peracetic Acid Concentration

Peracetic acid is often used in bottling plants as a terminal disinfectant. There are several methods of measuring peracetic acid concentration and these are reviewed here: 


A titration technique involves the use of three different chemicals and relies on detecting a colour change, followed by a calculation. 


The simplest method utilises test strips which change colour on immersion in the test solution. The colour is related to the concentration in mg/L.


Conductivity measurement is not reliable and requires addition of a tracer (nitric acid) to the peracetic acid. 

A recent development has seen the emergence of peracetic acid sensitive electrodes. The test solution is made to flow through a cell where the electrodes produce a signal related to concentration. The whole system can be made automatic, so that top up occurs as the solution becomes depleted.

Safer Alternative to Ozonation of Water

Problems of bromate formation when ozonating water containing small amounts of bromide are well known.  Even concentrations of bromate as low as 10 millionths of a gram per litre can be considered carcinogenic.  However, ozone is very efficient in killing unwanted microorganisms in water.

Alternatives are few and far between, but some new technology has appeared on the scene which may change this.  UV has been used in the past, but still has shortcomings, particularly for destruction of spore-forming microorganisms in high solids water.  However, the synergistic effect of combining UV with ultrasound opens up new possibilities.

The ultrasonic emitter, located directly in the UV radiation chamber, causes the formation of minute super-heated steam voids in the water under low pressure. These voids form around spores, bacteria and cysts. When the voids collapse, zones of extreme temperature and pressure are created destroying microorganisms in close proximity.

At the same time, free radicals, hydrogen peroxide and other active species are generated in the process. They provide a significantly enhanced disinfection and photochemical oxidation of microorganisms compared with conventional UV treatment.  An added bonus is that the ultrasound action prevents any build up of inorganic deposits on quartz sleeves and chamber walls, thereby maintaining optimum UV intensity.

Bromates are not formed, therefore removing the dangers associated with ozonation techniques.