Hurdle concept Flashcards
– introduced by Leistner in 1976; the complex interactions of temperature, water activity, pH, redox potential, etc. are significant for the microbial stability of foods
Hurdle effect
Principles of hurdle technology
Complex interactions of temperature, pH, water activity, etc. are significant for the microbial stability
Prevents the microorganisms from multiplying and causing them to remain inactive or even die
Microorganisms should not be able to “jump over” all the hurdles present in the foods
Preservative factors or hurdles disturb the homeostasis of the microorganisms
The major hurdles and its applications in food preservation
- F = High temperature - heating
- T = Low temperature - chilling, freezing
- aW = Reduced water activity - drying, curing, conserving
- pH = increased acidity - acid addition or formation
- Eh = Reduced Eh - removal of O2 or addition of ascorbate
- Pres. = Preservatives - sorbates, nitrates, sulfites
- c. f. = Competitive flora - microbial fermentations
Symbols:
F
t
aw
pH
Eh
pres.
K-F
V
N
Heating
Refrigeration
Water activity
Acidification
Redox potential
Preservatives
Competitive organisms
Vitamins
Nutrients
Case 1
Some of the microorganisms in the area can get past a few obstacles, but none of them can clear them all at once. Food is therefore steady and secure. Because all obstacles are portrayed as having the same intensity, which is rarely the case in actuality, this scenario is simply a theoretical one.
Case 2
There are main obstacles and minor obstacles.
Case 3
Few obstacles are enough to ensure stability of the product
Case 4
Typical barriers are insufficient to stop food spoiling or food poisoning, if there are too many unwanted microbes present.
Case 5
Food is nutrient and vitamin-rich, which may permit the rapid proliferation of microbes over a short period of time.
Case 6
Microorganisms in food that have been sub-lethally harmed are demonstrated. These spores lack vitality, which are therefore hindered by fewer or lower barriers
Sterilization vs, Pasteurization in terms of elimination of microbes
Sterilization = total
Pasteurization = partial
Sterilization vs, Pasteurization in terms of processing temperatures
Sterilization = above 100 C
Pasteurization = below 100 C
Sterilization vs, Pasteurization in terms of impact on nutritional qualities
Sterilization = deep
Pasteurization = low
Sterilization vs, Pasteurization in terms of lifetime
Sterilization = long
Pasteurization = short
Sterilization vs, Pasteurization in terms of storage
Sterilization = room temperature (pantry)
Pasteurization = low temperature (refrigerator)
requires that the milk be held at a minimum of 161°F for 15 seconds
High-Temperature, Short Time (HSTS) pasteurization
uses much higher temperatures varying from 275-302°F for 4-15 seconds.
Ultra-High Temperature (UHT) pasteurization
- the use of mathematical and computer modeling to describe and predict the behavior of foodborne microorganisms
- computer-based software packages which allow the user to estimate the rate of microbial growth or get an indication of whether growth of a particular microorganism will occur under a specified set of conditions. The models are based on laboratory-generated data.
Predictive microbiology
Browser for predictive microbiology
ComBase
Pathogen Modeling Program (PMP) Online
a mathematical model used to describe bacterial growth, incorporating three phases: lag, exponential, and stationary, and is often used in predictive microbiology to understand and predict microbial growth in food and other environments.
Baranyi model
HACCP
Hazard = Danger to Health
Analysis = Investigation of the hazard
Critical = Crucial for containment
Control = Handling of conditions
Points = Position in the process
is a food safety management sytem that is used to identify and control hazards within the production and processing system.
HACCP
7 basic principles of HACCP
- Conduct a hazard analysis
- Identify the critical control points
- Establish critical limits
- Monitor CCP
- Establish corrective action
- Verification
- Documentation
is the process to find and take necessary prevention measures
CCP
