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 need water to grow (but not necessarily survive)  Importance of water activity (a w )  Minimum activities at which active growth can occur  Bacteria 0.90 - 0.97  Yeasts 0.88  Fungi 0.61 – 0.88

Water activity a w  Water activity definition  The ratio of the vapour pressure of water in a material to the vapour pressure of water at the same temperature.

Water activity and food types a w 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

Microbial development factors  Intrinsic  Environmental  Implicit  Processing

Microbial development factors Intrinsic  Nutrients  pH  Oxygen  Water activity  Preservatives

Microbial development factors Environmental  Relative humidity  Temperature  Atmosphere

Microbial development factors Implicit  Specific growth rate  Mutualism  Antagonism  Commensalism

Microbial development factors Processing  Filtration  Irradiation/sub-micron filtration  Packaging  Pasteurisation

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 organisms  Is oxygen readily available?  Are chemical preservatives, CO 2 or ethanol present?

Sources of challenge - Implicit  Growth rate - 1 cell can produce 10 7 cells in 8 hours!  Mutualism/antagonism/commensalism some organisms subdue or promote others.  Are toxins or flavour defects possible?

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

Sources of challenge - Environment  Relative humidity - it’s water!  Temperature - bugs grow faster in warmer products!  Atmosphere – normal, with CO 2 or nitrogen flushed?

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.

Effects of microbial contaminants  Haze or filament development  Bottle distortion  Change in aroma or taste  Presence of mould pellicles

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

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?

Thank you for your attention! Are there any immediate questions? There will be another opportunity in the panel session