Transcript HSA - EPRALIMA

Food Safety
Training Course
Co-financiado:
Microorganisms and
food
5| 25 Microorganisms and food
Microorganisms • What are they?
• Main characteristics of living beings?
• Functions and applications?
4| 25 Microorganisms and food
Microbial Growth • What do you understand by microbial
growth?
• What factors affect microbial growth?
• How can we control the growth?
5| 25 Microorganisms and food
Microbial Growth
crescimento
em condições
Growth in optimum
óptimas
conditions
crescimento em outras
Growth in other
condições
situations
Log10
células
/mL
Tempo
Time
Microbial growing stages in a liquid environment. A – Lag stage; B- log stage; C- stationary
stage and D- death stage
6| 25 Microorganisms and food
Microbial
growth factors
• Intrinsic factors
- Nutrients
- pH
- Water activity
- Available oxygen
• Extrinsic factors
- Temperature
- Relative humidity
- Atmospheric oxygen
• Other factors:
- Biological structures
- Natural antimicrobial substances
7| 25 Microorganisms and food
Microbial
growth factors Temperature
Temperature
Temperature is one of the most relevant
factors for microbial growth .
8| 25 Microorganisms and food
Microbial
growth factors Temperature
Main cause that lead to Intoxications :
• Utilization of risk temperatures while
conserving food/meals;
• Utilization of inadequate temperatures
while preparing/processing those foods
(under processing);
9| 25 Microorganisms and food
Microbial
growth factors –
Hurdle effect
Adapted from: Adams, M.R. and Moss, M.O., 1995
10| 25 Microorganisms and food
Microorganisms • Main groups with importance for FS:
–
Bacteria
• Main characteristics
–
Fungi (Molds and yeasts)
• Main characteristics
11| 25 Microorganisms and food
Bacteria
•
•
•
•
Unicellular;
Various forms (cocci, bacilli, spirilla);
Some develop resistant structures (spores);
Main cause of food intoxications of
biological origin.
12| 25 Microorganisms and food
Bacteria
Photos: www.denniskunkel.com
13| 25 Microorganisms and food
Fungi
(molds and
yeasts)
•
•
•
•
•
•
Unicellular (yeasts);
Multicellular (molds or filamentous fungi);
Great decomposers of organic matter;
Widely used for making food and beverages;
Some are eatable (mushrooms);
Responsible for deteriorating most fruits
and vegetables.
14| 25 Microorganisms and food
Molds and
yeasts
Some utilizations of fungi:
a) Some eatable mushrooms. b) beer ; c) bread; d) Roquefort cheese with blue mold; e) e f) Camembert
an brie cheeses (respectively) with white mold.
15| 25 Microorganisms and food
Molds and
yeasts
Mold on food
16| 25 Microorganisms and food
Main sources
• What are the sources of microorganisms
that are present on foods?
– Soil;
– Water;
– Air;
– Handlers;
– Utensils and equipments;
– Products themselves or raw
materials used in their fabrication.
17| 25 Microorganisms and food
Main sources
• Soil
- Source of spore forming bacteria, fungi and
yeasts;
- Addition of manure – faecal
microorganisms;
- Dissemination of microorganisms:
wind, rain, animals, fertilization…
18| 25 Microorganisms and food
Main sources
What measures should be taken to
avoid/reduce contamination?
Table I – Effect of washing on the flora of vegetable products
Type of product
Tomato
Collards
Num. of microorganisms
Not washed
> 1 000 000/ cm2
Washed
400-700/cm2
External leaves not washed
1 000 000 – 2 000 000/g
Internal leaves washed
200 000 – 500 000/g
Internal leaves
100 – 10 000/g
Data: Jay, J.M., 1996 e Lacasse, D.. 1995.
19| 25 Microorganisms and food
Main sources
• Water
- May contain various types of microorganisms
(origin and level of pollution);
- Utilization of potable water!
How to avoid contamination?
20| 25 Microorganisms and food
Main sources
•Air
- Non favourable environment for microbial
growth;
- Excellent conveyer of microorganisms from
other sources: sneezing, coughing, agricultural
activities …
How to reduce contamination caused by
microorganisms transmitted by air?
21| 25 Microorganisms and food
Main sources
• Food
Diverse and proper flora :
– Vegetables
– Animals
Intestines
Soil
Animals
Water
22| 25 Microorganisms and food
Main sources
• Handlers
- Diverse and own flora (faecal matter and
skin);
- Main problems?
• Utensils and Equipments
- Do not have own microflora;
- Main cause of
CROSS CONTAMINATIONS!!!
23| 25 Microorganisms and food
Cross
contamination
• What is “cross contamination”?
Microorganisms present in raw foods,
utensils and contaminated surfaces are
transferred to prepared or washed foods or
to clean surfaces..
- What are the main conveyers?
- How to prevent/avoid?
- Examples
24| 25 Microorganisms and food
Risks and
hazards
• Difference between “Hazard” and “Risk”
- What is the origin of hazards?
- Examples
25| 25 Microorganisms and food
Riscos e
Perigos
Table II – Classification of hazards related to food safety
Types of hazards
Examples of hazards
Examples of associated foods
Potential illnesses
Salmonella
Eggs, poultry, raw milk and milk
products
Salmonellosis
Hepatitis A virus
Fish, seafood, vegetables, water,
fruit, milk
Hepatitis A
Bones, fish bones,
glass, metal, stones
Lesions
Aflotoxins
Nuts,
corn, milk
products
Dioxins
Fish, animal fat
and
milk
Cancer,
malformations,
alterations of the nervous
system diseases; hormonal
alterations…