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7.

Improved safety: for the product, for operators and for the environment

Microbiological Principles, in other words: what you would never like to find in the end product.

The air that surrounds us contains a variety of small, solid or liquid particles that compose the atmospheric aerosol. Due to sedimentation, it is practically impossible to find particles larger than 10μm. The human eye moreover, is not able to perceive particles with a diameter inferior to 30μm; it is therefore impossible to visibly judge the contamination of the air. It is also important to consider that the particles with a dimension inferior to 1μm do not sediment and that the microbes have dimensions that vary from 0,3 to 1μm; air is thereby an excellent vehicle of microbial contamination. The micro-contamination conveyed is therefore a very high risk factor in beverage productions, in particular as concerns cold fill products, as a microbic contamination at this stage of the production process is an almost certain source of contamination.

The microbial contamination is a very high risk factor in beverage productions, in particular as concerns cold fill products
Fig.7.1. The microbial contamination is a very high risk factor in beverage productions, in particular as concerns cold fill products
7.1.

Microbic Contamination

Microbial colonies
Fig.7.2. Microbial colonies

The majority of the beverages on the market due to their level of sugar and water content represent a perfect habitat for the growth of microorganisms.
Moulds, yeasts and bacteria are the main types of microorganisms that may cause contamination and alteration of a product; not necessarily dangerous for humans. The microbic contamination may arise at any level of the production chain, from the harvest or production of the ingredients to the end package. The transmission occurs normally by contact with a non-sterile entity, that could be solid, liquid or gaseous.

Bacteria

Bacteria are unicellular prokaryote organisms and have a very simple internal structure (no nuclear membrane, no membrane organelle) if compared to those of other living organisms. Their reproduction (bacterial growth) is the outcome of the division of every single cell into two parts exactly identical to the initial one, via a mechanism named fission. If the growth conditions are optimum, a bacteria cell is able to multiply every 20 minutes, so a single bacteria may originate almost 70 billion cells in 12 hours. The factors that influence reproduction include the quantity of nutrients available, humidity, pH, level of oxygen, and the presence of substances able to inhibit growth.
The substances which the majority of bacteria require are carbon, hydrogen, oxygen, nitrogen, phosphorous, sulphur, magnesium, potassium, sodium, calcium and iron. The microorganisms grow by metabolizing certain food components such as carbohydrates and proteins. Temperature, pH and presence of water play a significant role in controlling the reproduction speed of the bacteria. In general, a large number of these microorganisms grow better in a neutral environment and require a certain minimum quantity of water. The temperature range that guarantees an optimum growth is influenced by the microorganism family; more or less, also for the more thermo-resistant bacteria, the reproduction stops at temperatures exceeding 70-80° C. The oxygen required for an optimum growth varies significantly from one species of bacteria to the other. Some microorganisms call for the presence of free oxygen in order to survive and multiply (aerobes) whereas others are not able to survive in presence of oxygen (anaerobes). If the temperature, the pH and the presence of humidity in substrata are favorable, the bacteria start to reproduce and to grow significantly until the source of the nutrition or the surrounding conditions do not change, for example, due to a lowering of the pH.

It is possible to recognize 4 main phases of the microbic development. The first phase (latency period or lag phase) is at growth rate zero. The cells start to adapt to the new conditions and the product within which they are inserted. Often, the nutritional use of diverse substrata occurs by means of specific enzymes that typically are not constitutional and must be appropriately developed by the bacteria. In the exponential phase (log phase) each cell of the microbial population enjoys in the same measure the reproduction conditions so that within the same time span (generation time) each one produces a copy of itself. The exponential phase lasts for a brief period due to the limitation of the nutritional resources available and the accumulation of toxic products generated by the same micro- organisms. The maximum obtained by the curve depends on the quantity of nutritional factor available. The growth stops, in fact, when the nutrient finishes or when the system becomes intoxicated.

Microbial growth phases
Fig.7.3. Microbial growth phases
At the end of this stationary period, in which the number of cells remain almost constant, in the absence of external interventions, the culture deteriorates; the speed of inactivation and death rate of the microorganisms prevails over growth. Surrounding conditions being equal, the bacterial growth rate will be tied to the initial contamination present inside the product and the time of exposure left for the microorganisms to develop.

Moulds and Yeasts

Moulds are multicellular fungi that are reproduced by the formation of spores (single cells that can multiply so much so that in turn generate an organism). They are formed in vast quantities and are easily conveyable by air. When they land on food surfaces, if the conditions of the substrata are favorable, they can grow and reproduce. Moulds are able to grow only under certain conditions of acidity. In particular, we can note their growth in solutions with a pH around 3,5.

The yeasts are made up of single cells that can be easily distinguished from bacteria, as they are much bigger. Normally they are oval in shape and longer in length; some have no flagellum or other type of transfer organ.
The majority of yeasts do not live on the ground but adapt to an environment rich in sugars, they are in fact very useful within the food field as regards the fermentation transformations of foodstuffs (e.g alcoholic fermentation for the production of wine, beer and bread). Yeasts, on the contrary to moulds, do not reproduce across spores. Yeasts are for the majority, gas producers, as when they develop, they produce gas.

Bacteria Yeasts Moulds
Lactobacillus brevis Cryptococcus albidus Aspergillus niger
Lactobacillus buchneri Debaryomyces hansenii Botrytis cinerea
Lactobacillus paracasei Picha anomala Byssochlamys fulva
Lactobacillus paralens Picha membranaefaciens Byssochlamys nivea
Lactobacillus plantarum Rhodotorula glutinis Geotrichum candidum
Lactococcus lactis Saccharomyces cerevisiae Neosartorya fischeri
Leucaonostoc mesenteroides Torulaspora delbrueckii Penicillum citrinum
Enterobacter cloacae Zygosaccharomyces bailii Penicillum expansum
Gluconobacter oxydans Zygosaccharomyces florentinus Talaromyces flavus
Alicyclobacillus acidocaldarius Zygosaccharomyces microellipsoides
Alicyclobacillus acidoterrestris Zygosaccharomyces rouxii
Table. 7.1.
7.2.

Contamination Control

Contamination control is of primary importance, for the product, the container and the environment in which the filling operations are performed. The first rotary aseptic lines for PET containers introduced around the 1990’s, solved the environmental contamination control problems by installing the machine inside a controlled room, the so called "Clean Room". Afterwards, the so-called "Microbiological Isolator" was introduced and integrated on the machines as a contamination controlled environment pressurized by HEPA filtered air. Fundamental features of the environment contamination control is a correct filtration of the air inside the controlled environments, the management of the pressures of the various environments to control the path of possible particles, a correct management of the air flows, a correct sampling of the environment, the quality control and a correct management of the COP and SOP cycles.
7.3.

Microbiological Isolator

The microbiological isolator is an environment contamination control system and is part of the aseptic system, in the process areas (sterilization, rinsing, filling and capping) as well as in the bottle and caps conveying areas. A good design of the machine safeguards are an integral part of the isolator as they must ensure easy cleaning, they must not have any stagnant spots where possible contamination may hide, all access hatches must be airtight. A contamination controlled system must also manage the air filtration operations, direct sterile air towards the various machines, maintain the overpressures set in the various environments and intake the air from the machines. The microbiological isolator is fitted with: intervention gloves, sterile object transfer box and material discharge container to facilitate operations during production, perform sampling activities and resolve any possible jams without having to open the actual isolator. Said systems reduce the major contamination risk factor to zero in an aseptic system, that is, direct operator intervention inside the sterile environment. The volumes to be controlled are reduced to a minimum as the isolator is installed directly on the base frames of the filling and container handling machines; the times required to sterilize the environments are therefore minimized and subsequently this leads to a reduction in sterilizing agent consumption.
Microbiological isolator
Fig.7.4. Microbiological isolator
7.4.

Air Filtration

The air filtration of the treatment and filling environments of an aseptic line, is performed in three consecutive stages. The filters used are classified on the basis of different parameters, the most important ones are:

  • field of use (substances and conditions of use)
  • nominal flow rate
  • grade of resistance
  • level of powders that may accumulate
  • efficiency

The air filtration of the treatment and filling environments of an aseptic line, is performed in three consecutive stages. The filters used are classified on the basis of different parameters, the most important ones are: / field of use (substances and conditions of use) / nominal flow rate / grade of resistance / level of powders that may accumulate / efficiency Efficiency plays a major role in the selection of a filter. Said parameter is expressed on the basis of the percentage of particles retained. Therefore, a filter with an efficiency of 99,999%, allows one particle through 100000. The absolute filters, classified with the code HEPA (High Efficiency Particulate Air filter), are such if they have a minimum efficiency of 99,97% at the 0,3 μm particle size.
For smaller particles, it is best to use a series of different types of filters, each one with a higher efficiency. The HEPA filters are the last of a series: in order to attain better results, they have to be "terminal", in other words, once the air has gone through the filters it has to reach the working area without meeting any obstacle along its way. This procedure of filter installation in addition to increasing the efficiency of the system permits a longer service life of the HEPA filters.
Air filtration efficiency standards
Fig.7.5. Air filtration efficiency standards – Reduction of particles per volume of air
7.5.

Differential Pressures

A controlled environment may have a number of chambers with diverse contamination control requirements where the safeguarding of the product is the primary goal. In this case, all chambers must be kept at static pressure (overpressure) slightly above the atmospheric pressure, in order to avoid infiltrations from the outside. By placing the chamber in overpressure, the only way in for the air is across the HEPA terminal filters. The pressures in the chambers must remain stable in the long term so as the air can always flow from the cleaner environments towards the dirtier ones. When toxic or unpleasant substances are in the controlled areas (e.g chemical sterilization cycles), for safety and environmental protection reasons, it is recommendable to reduce the differential pressures as far as possible.
This is why normally there are special air intake areas where the overpressure as compared to the external environment is maintained. Air is expelled by means of controlled vents and these operate continuously and constantly.
HEPA filters
Fig.7.6. HEPA filters

Table of contents

  1. Introduction
  2. 1.Markets, opportunities, a comparison of the technologies
    1. 1.1. “High acid” and “Low acid” beverages
    2. 1.2. Juices and Nectars
    3. 1.3. Sport Drinks
    4. 1.4. Tea and infusions
    5. 1.5. Functional Beverages
    6. 1.6. Milk-based products
    7. 1.6.1. UHT Milk
    8. 1.7. Historical perspective: Evolution of the technology from the Roman era to our day and age
    9. 1.7.1. "Aseptic" technology in the Roman era
    10. 1.7.2. The Roman "filling, capping and storage process"
    11. 1.8. Technologies to meet market demand
    12. 1.8.1. Use of preservatives
    13. 1.8.2. Hot fill
    14. 1.8.3. Ultra-clean filling
    15. 1.8.4. Aseptic Filling
    16. 1.8.5. Aseptic Blow Filling
    17. 1.9. Advantages and disadvantages of containers for beverages
    18. 1.9.1. Glass
    19. 1.9.2. Polylaminate carton
    20. 1.9.3. PET
    21. 1.9.4. HDPE
    22. 1.9.5. Cans
    23. 1.9.6. Pouches
    24. 1.10. Caps, closures, fitments
  3. 2.The right direction of sustainability
    1. 2.1. Material
    2. 2.2. Energy
    3. 2.3. Space
    4. 2.4. Time
  4. 3.Thermal treatment for product
    1. 3.1. Heat Exchangers for Liquid Products
    2. 3.1.1. Plate Heat Exchanger
    3. 3.1.2. Single Tube Heat Exchanger
    4. 3.1.3. Multi Tube Heat Exchanger
    5. 3.1.4. Triple Tube Heat Exchanger
    6. 3.1.5. Spiral Tube Heat Exchangers
    7. 3.1.6. Scraped Surface Heat Exchangers
    8. 3.2. Indirect and Direct Heating
    9. 3.3. Direct Heating UHT and ESL Designs
    10. 3.3.1. Direct Injection
    11. 3.3.2. Direct infusion
    12. 3.4. The best heat exchanger for your application
    13. 3.4.1. Heat Damage to food
    14. 3.4.2. System Selection Criteria
    15. 3.5. Conclusions
  5. 4.Understanding aseptic filling technology
    1. 4.1. Aseptic technology: an integrated system, not a series of connected machines.
    2. 4.2. Structure of an aseptic filling line
    3. 4.2.1. Sterilization
    4. 4.2.2. Container sterilization
    5. 4.3. Treatment of containers
    6. 4.3.1. Peroxyacetic Acid (POAA or PAA)
    7. 4.3.2. H2O2
    8. 4.4. PAA WET container sterilization
    9. 4.5. PAA vapour container sterilization
    10. 4.6. H2O2 CHP container sterilization
    11. 4.7. H2O2 VHP container sterilization
    12. 4.8. Preform sterilization technology
    13. 4.8.1. CHP sterilization
    14. 4.8.2. VHP sterilization
    15. 4.9. Cap sterilization technology
    16. 4.9.1. PAA spray sterilization
    17. 4.10. PAA immersion sterilization
    18. 4.10.1. CHP sterilization
    19. 4.10.2. VHP sterilization
    20. 4.10.3. Pre-sterilized caps handling
    21. 4.11. Energy-based sterilization without chemicals
    22. 4.11.1. UV light sterilization
    23. 4.11.2. Pulsed light sterilization
    24. 4.11.3. Ionizing radiation Sterilization
    25. 4.11.4. Electron beam sterilization
    26. 4.12. Aseptic Filling
    27. 4.12.1. Volumetric electronic filling
    28. 4.12.2. Weight filling
    29. 4.12.3. Other filling technologies
    30. 4.13. Capping
    31. 4.14. Bottle handling
    32. 4.15. Ancillary process equipment
    33. 4.15.1. Sterilizing solution production
    34. 4.16. Sterile water production
    35. 4.16.1. Utilities and fluids handling
    36. 4.16.2. CIP, SIP, COP, SOP
    37. 4.16.3. Integration of ancillary process units
    38. 4.16.4. Piping
    39. 4.16.5. Simplification of line handling
    40. 4.16.6. Radiation-based fluids sterilization
    41. 4.17. Line automation
  6. 5.Your new Aseptic Line
    1. 5.1. Preliminary Checklist
    2. 5.1.1. Volumes
    3. 5.1.2. Products
    4. 5.1.3. Design
    5. 5.1.4. Costs
    6. 5.1.5. Centralising production
    7. 5.2. Evaluation of the investment
    8. 5.2.1. Choose according to your own needs: the value curve
    9. 5.2.2. How to measure the performances of an aseptic line
  7. 6.Good maintenance: the best way to preserve the value of the investment
    1. 6.1. Service Culture
    2. 6.2. TPM
  8. 7.Improved safety: for the product, for operators and for the environment
    1. 7.1. Microbic Contamination
    2. 7.2. Contamination Control
    3. 7.3. Microbiological Isolator
    4. 7.4. Air Filtration
    5. 7.5. Differential Pressures
  9. 8.Aseptic filling and FDA
    1. 8.1. FDA Validation
    2. 8.2. Electronic Validation
    3. 8.2.1. GAMP 4 Module
    4. 8.3. Paper Recording vs Electronic Recording
  10. 9.Sell Aseptic to sell "more" and sell "better"
  11. 10.The Future of Aseptic
  12. Conclusions
  13. Addendum
    1. 1. Thermal treatment for products
Reference: Schlünder,E.U.:Dissertation Techn.Hochschule Darmstadt D 17, 1962.