SLIDE 1
Bottled waters technical workshop
Microbiological challenges Dr Philip Ashurst
philip@ashurstassociates.co,uk
Effects of micro-organisms on foods
- Spoilage
- Cause illness
- Fermentation
Bottled waters technical workshop Microbiological challenges Dr - - PowerPoint PPT Presentation
Bottled waters technical workshop Microbiological challenges Dr - - PowerPoint PPT Presentation
Bottled waters technical workshop Microbiological challenges Dr Philip Ashurst philip@ashurstassociates.co,uk Effects of micro-organisms on foods Spoilage Cause illness Fermentation Micro-organisms and water Micro-organisms
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Micro-organisms and water
- Micro-organisms need water to grow (but
not necessarily survive)
- Importance of water activity (aw)
- Minimum activities at which active growth
can occur
- Bacteria
0.90 - 0.97
- Yeasts
0.88
- Fungi
0.61 – 0.88
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Water activity aw
- Water activity definition
- The ratio of the vapour pressure of water
in a material to the vapour pressure of water at the same temperature.
SLIDE 5
Water activity and food types
aw Product types 0.9 - 1.00 Most beverages and water 0.85 – 0.95 Cured meats, ham, salami 0.75 – 0.85 Dry cheeses, flour, cakes, cereals 0.70 – 0.75 Pickles and jams 0.60 – 0.70 Dried fruits <0.60 Dehydrated foods
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Microbial development factors
- Intrinsic
- Environmental
- Implicit
- Processing
SLIDE 7
Microbial development factors Intrinsic
- Nutrients
- pH
- Oxygen
- Water activity
- Preservatives
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Microbial development factors Environmental
- Relative humidity
- Temperature
- Atmosphere
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Microbial development factors Implicit
- Specific growth rate
- Mutualism
- Antagonism
- Commensalism
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Microbial development factors Processing
- Filtration
- Irradiation/sub-micron filtration
- Packaging
- Pasteurisation
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Sources of challenge Intrinsic
- The ingredients – is it just water or with added
components?
- What is the end product pH? Is it above or below 4.0?
- Water activity – adequate to support wide range of
- rganisms
- Is oxygen readily available?
- Are chemical preservatives, CO2 or ethanol present?
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Sources of challenge - Implicit
- Growth rate - 1 cell can produce 107 cells
in 8 hours!
- Mutualism/antagonism/commensalism
some organisms subdue or promote
- thers.
- Are toxins or flavour defects possible?
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Sources of challenge – Processing
- Filtration – what is needed (or permitted)?
- Removal of viable organisms – use of UV?
- Packaging PET or glass?
- Equipment automated or manual?
- Carbonated or still
- Pasteurisation
- Hygiene standards & CIP systems
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Sources of challenge - Environment
- Relative humidity - it’s water!
- Temperature - bugs grow faster in warmer
products!
- Atmosphere – normal, with CO2 or
nitrogen flushed?
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Specific issues - The product
- Water - NM, Spring or bottled?
- Source, composition, treatments
- Flavoured water?
- Alcohol or PG based flavourings?
- Other added ingredients?
- What is being added?
Carbohydrates and nitrogen sources provide
nutrients.
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Effects of microbial contaminants
- Haze or filament development
- Bottle distortion
- Change in aroma or taste
- Presence of mould pellicles
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Microbial checks
- What to look for Water:
Bacterial counts at 20°C & 37°C E.coli and presumptive coliforms Yeasts & moulds Parasites (Cryptosporidium and Giardia)
- Water plus:
Yeasts & moulds Bacterial counts at 20°C & 37°C E.coli & presumptive coliforms (depending on pH) Parasites
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What are the challenges for your products?
- What are you producing?
- How good is your hygiene?
- Assess the risk from ingredients
- Are your packaging components clean?
- What processing do you use?
- What testing do you employ?
- What are your complaints levels?
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