24 Questions
What is the definition of hurdle technology?
The combination of preservation techniques to establish hurdles that microorganisms cannot overcome
Which method requires extremes to be effective as a single preservation method?
High concentration of chemical preservatives
Which hurdle is categorized as a physicochemical preservation hurdle?
UV irradiation
Which preservation hurdle is microbially derived?
Lactic acid
Which method is not categorized as a potential preservation hurdle?
Frying
Which factor is considered as a physical preservation hurdle?
O3 (ozone)
What are some examples of hurdles in preservation technology?
Monolaurin, increased pH, and reduced aw
What is the most important factor for high- and intermediate-moisture foods in hurdle technology?
Intrinsic properties
In which practical example is adequate control of Listeria monocytogenes achieved?
Lowering the pH to 5.5
What does the interaction of hurdles in preservation technology consider?
Heat resistance decreases at low pH
In Hurdle Technology, what is the storage life for shelf-stable products (SSP)?
Weeks to months
What is the heat treatment duration for liver, blood, and Bologna-style sausages in SSP?
20-40 minutes at 103-108 °C
What does traditional Italian SSP have an aw of?
~0.96-0.97
What does high moisture meats (aw > 0.90) refer to in Hurdle Technology?
~weeks to months unrefrigerated shelf-life
In hurdle technology, which of the following is considered a physicochemical preservation hurdle?
Salt addition
What preservation method requires extremes to be effective as a single preservation method in hurdle technology?
High concentration of chemical preservatives
Which of the following is NOT considered a potential physical preservation hurdle in hurdle technology?
Water activity
What is the deliberate combination of existing and novel preservation techniques in order to establish a series of hurdles that microorganisms should not be able to overcome?
Food hurdle technology
Which of the following is a microbially derived potential preservation hurdle in hurdle technology?
Lactic acid
In the context of preservation hurdles, what is the main disadvantage of using hurdle technology?
Potential negative impact on consumer acceptance
What is the most important consideration for achieving adequate control of Listeria monocytogenes in a chilled product using hurdle technology?
Combining pH, salt content, and storage temperature
Which characteristic is essential for applying hurdle technology to high- and intermediate-moisture foods?
Multi-target effect and synergistic interaction
What combination of factors could be used to achieve adequate control of Listeria monocytogenes in a chilled product through hurdle technology?
pH 5.5, 5% NaCl, and storage at 4 °C
What is the primary purpose of achieving a low Eh in addition to other hurdles in shelf-stable products (SSP)?
Inactivating vegetative cells and damaging spores
Study Notes
Hurdle Technology Definition
- Hurdle Technology is the deliberate combination of existing and novel preservation techniques to establish a series of hurdles that microorganisms cannot overcome.
Types of Hurdles
- Physicochemical preservation hurdle: pH, aw, Eh, temperature
- Microbially derived preservation hurdle: bacteriocins, enzymes
- Physical preservation hurdle: temperature, pressure, radiation
Hurdle Technology Principles
- Requires extremes to be effective as a single preservation method
- Combination of hurdles to achieve preservation
- Interaction of hurdles considers the cumulative effect of multiple hurdles
Preservation Hurdles
- pH: a physicochemical preservation hurdle
- aw: a physicochemical preservation hurdle
- Temperature: a physical preservation hurdle
- Radiation: a physical preservation hurdle
- Pressure: a physical preservation hurdle
- Bacteriocins: a microbially derived preservation hurdle
- Enzymes: a microbially derived preservation hurdle
Examples of Hurdles
- Heat treatment
- Storage life
- aw control
- pH control
High- and Intermediate-Moisture Foods
- Most important factor: aw control
- Characteristic: aw > 0.90 (high moisture), aw < 0.90 (intermediate moisture)
Shelf-Stable Products (SSP)
- Storage life: long-term
- Heat treatment duration: 30 minutes for liver, blood, and Bologna-style sausages
- Traditional Italian SSP: aw < 0.95
Listeria monocytogenes Control
- Most important consideration: aw control
- Combination of factors: aw control, temperature control, pH control, and other hurdles
Disadvantages
- Main disadvantage: increased complexity of preservation process
Primary Purpose of Low Eh
- To achieve preservation in addition to other hurdles in SSP
Learn about Leistner's concept of hurdle technology and the deliberate combination of preservation techniques to create barriers for microorganisms. Understand the use of single preservation methods and their effectiveness in producing safe, unspoiled foods.
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