Learning outcomes:
After completion of this course students are expected to be able to:
- describe main preservation processes and the spoilage associated organisms for specific food products;
- explain the factors that influence growth and inactivation of micro-organisms in food products qualit...
1. Food Safety ....................................................................................................................................................................................................................... 2
2. Minimal processing of foods ............................................................................................................................................................................................. 5
3. Survival strategies ............................................................................................................................................................................................................ 7
4. Biofilms........................................................................................................................................................................................................................... 11
5. Fungi .............................................................................................................................................................................................................................. 15
6. Molecular Ecology of the Gastrointestinal tract .............................................................................................................................................................. 16
7. GI tract functionality ....................................................................................................................................................................................................... 25
Probiotics, prebiotics and microbial health effects in the intestine. ......................................................................................................................................... 29
8. BIOMARKERS FOR ROBUSTNESS ..................................................................................................................................................................................... 35
9. Whole Genome Sequencing ............................................................................................................................................................................................ 36
10. Viruses in food ........................................................................................................................................................................................................... 36
11. Microbial Risk assessment ......................................................................................................................................................................................... 38
12. Sampling and monitoring ........................................................................................................................................................................................... 39
13. Quantitative microbiology ......................................................................................................................................................................................... 43
14. Ecology of Campylobacter .......................................................................................................................................................................................... 44
15. Detection methods ..................................................................................................................................................................................................... 45
,1. Food Safety
Learning goals
• Know the impact of food borne diseases.
• Get an understanding of the possibilities and limitations of novel approaches including FSOs, quantitative
microbiology, and risk analysis for the production of safe foods.
Difference between a Microbiological Criterion and an FSO/PO : A food safety objective (FSO) specifies the maximum
permissible level of a microbiological hazard in a food commodity at the moment of consumption and is based on a
management decision regarding the acceptable risk of the hazard to the population or on a public health goal.
Maximum hazard levels at other points along the food chain are called performance objectives (POs) and can be
derived from the FSO. The current definitions for FSO and PO are that an FSO is: ‘the maximum frequency and/or concentration of a hazard in a food at the
time of consumption that provides or contributes to the appropriate level of (health) protection (ALOP),’ whereas a PO is: ‘the maximum frequency and/or
concentration of a hazard in a food at a specified step in the food chain before consumption that provides or contributes to an FSO or ALOP, as applicable.’
FSOs and POs are general risk-based objectives for a food commodity. An FSO can for example stipulate that the probability of survival of Clostridium
botulinum in sterilized foods at maximum is 1 spore in 1010 cans. Such an objective cannot be tested by any practical microbiological method.
Knowledge clip – 1.1b food safety – the bad guys
In the US it was estimated that around 160,000 people get ill because of foodborne disease, 430 per million patients get hospitalized and 10 per million dies.
What percentage by case. Illnesses – hospitalization – death
Relevant for illnesses
Campylobacter, Clostridium perfringens, Salmonella nontyphoidal,
Norovirus.
Relevant for mortality
Listeria monocytogenes is very relevant due to high mortality. Severe
effects on YOPI
Toxoplasma gondii also show high mortality percentage.
Phages
Phages are viruses of bacteria. You can recognize bacteria by seeing their
resistance profile
Serotypes: serology – reaction to antibodies. To identify organisms to
fingerprint them.
Products related to causing organisms
Lambda IJ: identity or serotype
Mj: depends on mass of food products
Pij: prevalence of organisms (type I and fuj)
Qi: type factor. Specific characteristics of organisms thus only has i. Shows
strengths of organisms
,Aj: food factor. Survivability and growth possibilities.
Why the %positive eggs with Salmonella where higher in Denmark than in the Netherlands?
Chicken is usually consumed cooked in the Netherlands. In Denmark people eats raw food. Chicken is important for Campylobacter.
To control this HACCP is used. It consist of 7 important steps. But pre-requisites must be fulfilled such as GMP (good manufacturing practices), GHP (good
hygiene practices). The basics must be complete. If this are not fulfilled then HACCP will not work properly
For hazards you must identify hazards by using epidemiology results, scientific knowledge, expert advice, etc. Then is to determine the CCP which will influence
the risks for example pasteurization or cooling. For this critical limits are determined such as time and temperature of these processes. For defining hazards,
CCPs and limits global, specific and extensive risks assessments could be used (QRA). The last is usually performed by public authorities.
During operation you must monitor and determine corrective actions when the monitoring results out the critical limits. For example reprocessing. Also the
system must be verified and there should be documentation in order. Is crucial to keep procedures. All data must be well documented. Education of personal is
relevant. All this systems are used to control food safety.
To avoid problems interventions must be well established. CODEX: quantitative risk analysis
The FSO concept
Contamination starts at H0. There can be stages with reduction R (drying, heating) but there can also be growth
factors (such as the leavening of the dough). Additional contamination can also occur (for example hand, biofilms,
aerosols). All this factors must be below FSO (food safety objective). The left side of the equation regards the
industry where microbiological analysis and quantitative microbiology is done to determine the variables. On the
other hand, FSO are determined by the government who shall follow the epidemiology results and consumption
patterns.
Through this graph we can see how the FSO can be related
to the amount of cases in a year. If the number of cases is
set in an appropriate level of protection (ALOP) we can
relate that to the food safety objective. For example the
ALOP can be set as one case per million people per year and
depending on the virulence and number of servings will
determine how it will be related to the FSO. On the X axis
you can see the log on the number of organisms per serving
(dose per serving).
This concept FSO can be extended through the whole food
chain.
We start with an initial level of contamination (there can be
washing to reduce the level) but there can also be growth during storage and there can be additional contamination. All this must be done under PO
( performance objective). That is an intermediate FSO and its final level of primary production is the entry level for the food progressing. There can be
contamination in the process so PO must also be determined for this part of the chain. Then we have the entry level of the consumer.
Microbiological Food Safety Research
Combination of knowledge. Integration
For quantitative methods: Quantification of prevalence, initial concentrations, growth,
inactivation and recontamination are relevant.
Example: If you open a food product microorganisms can enter and you can calculate how
many microorganisms entered the product in five seconds.
Contamination rate = concentration of bacteria in the air * velocity * open area * exposure
time.
By using air filters you can reduce concentration in the air. By increasing the air flow then the
velocity can change and we can reduce the contamination area or exposure time by closing
the tap.
Ecophysiology
Is the response on stress factors
Physiology of specific targets, exhaustion.
Detection
Understand ecology and verification/monitoring/sampling to investigate roots of contamination and niches.
For that we need methods with low detection limits. Going more and more into molecular methods.
We need to collect data to see distribution of contamination of products by sampling.
Fermentation
Use microbiology to control microbiology.
Hygiene
Prevention are appropriate to avoid.
Information
Intelligent use of sources of information such as literature, database, experiments, experts.
Perception
AS technologists we will focus on real risks that are important to control.
Recontamination unit is cfu
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